#what is a FM receiver circuit

[wliam2ttrr]

https://www.futureelectronics.com/p/semiconductors--wireless-rf--receiver-ics/clrc63201t-0fe-112-nxp-2283646

NXP, CLRC63201T/0FE,112, Wireless & RF Receiver ICs

CLRC632 Series Multiple Protocol Contactless Reader IC (MIFARE/I-CODE1) -SOIC-32

[wheezyseeker99]

To Be Alone With You

Warnings: alcohol consumption, swearing, and sexual themes including oral (female receiving) and penetration (fm)

18+, MDNI

✨no summary, just vibe with it✨

If Jamie Drysdale wasn’t my best friend, I know as a fact that I wouldn’t be out in Philly with him after his win tonight. I had a long day at work. I would rather be bed rotting right about now, but I’m a supportive friend. I’ve known Jamie since him and my little brother went to the same hockey camp over a decade ago. The more they talked, the more gradually he started to become my little brother too.

Ever since I moved to Philly a couple years ago, I haven’t had much of a reason to get out. That was until Jamie got traded to the Flyers a few months ago. I don’t have many friends here so it’s nice to have the familiar face around. I started to go to his games, and he’s brought me along to some get togethers with some of his teammates. They started to become my friends too. Like tonight, I drove to the game in New York and then drove him and our friend Cam back to their practice arena to drop off their hockey gear. Now we’re at a bar in South Philly. I walked here from my row house a few blocks down and they carpooled in Jamie’s car. When I walked in, I immediately noticed Cam before I saw Jamie.

Cam York is what I call a perfect man, but he’s also Jamie’s teammate.

When I laid eyes on Cam for the first time, I think my brain short-circuited. It was when Jamie moved to town and he texted me the address he was staying at the time. Little did I know that it was Cam’s address. He answered the door and I almost went mute from how beautiful he was that first day. He’s at least 6 ft, pale skinned, and his red hair is his signature feature. I mostly like his eyes. They’re always the prettiest shade of blue. And I remember the way he laughed when I asked if I had the wrong address. I’m still surprised I even had the ability to stand.

Now that I’m a little more desensitized I can keep calm around him. Ever since Jamie came back from his shoulder injury that took him out for almost a month, he’s been looking for a major win on the ice. This win tonight was against one of the top teams in the league. And this is also the first time we’ve ever been out just the three of us. Usually it’s just us three hanging out at Cam’s or Jamie’s. And well, I guess it was the three of us until the ‘Jamie Drysdale fanclub’ showed up at the bar and dragged him to the dance floor. Cam and I stayed in the booth, watching Jamie be awkward in the group of girls.

I have had a solid 2 and a half drinks and 2 rounds of shots before I start giggling, and that’s how I know I’m getting drunk. The last time I got drunk I admitted to Jamie that Cam is the most attractive teammate he has, and now said teammate is sitting across from me. I realize I’m giggling and bite down on the inside of my cheek. Then I attempt to focus on people watching.

“You look like you’re having a good time.”

My eyes snap to Cam while he sips his drink. His bright eyes are staring a hole right through me. I pick up my glass and down the rest of my drink before I drag my eyes back to look at Jamie.

“I am. He looks like he’s about to throw up out there. It’s very entertaining for me.” I pick up my phone and try to stand. “I need to take a picture to send to my brother. He’d get a kick out of it too.”

I almost tumble to the ground when I stand and Cam is right behind me in an instant. His hands are on my hips, keeping me upright. The way his hands have a grip on me sends a tingle up my spine. I feel his hard body against my back.

“I’ll take a picture for you. Take a seat.”

I obey him and sit down. He takes the phone out of my hand, grazing his fingers against mine. I watch him as he takes a picture of Jamie. His back is turned to me, but I can tell that he’s smiling. I take a second to admire him. His tshirt is stretched over his shoulders and his jeans fit him just right. His baseball hat is placed backwards on his head. Every time I see him with a hat on, I want to toss it off and run my fingers through his hair and-

“You okay?”

He snaps me out of my dazed state. He’s smirking down at me as he lays my phone down on the table in front of me. He props an arm on the top of my booth and leans on it, studying me. I can feel my cheeks getting warmer by the second. He so caught me checking him out.

“Yes.” I choke out. “I’m good.”

He nods and bites his lip, looking back at the dance floor, but not before I notice how the low light in here hits his face so that I can see the little scar on his top lip. I’ve had dreams of that scar since I noticed it for the first time. I reach for my drink again but realized I finished it before I even tried to stand. I’m screwed.

“Do you want another?” He asks. I let out an involuntary giggle. I can feel his eyes on me again, but I try not to look at him as I grab my phone and purse.

“I think if I have another I’ll make some stupid fucking decision. I’m already giggling which is a bad sign. I probably need to walk home before I end up doing something bad.”

He takes my phone and purse out of my hands and sits them back down before I could try to stand again. I look at his face and his expression has changed. He looks more serious, kind of like how he looks on the ice. I bring my hand up to smooth out the crease between his eyebrows and I start giggling again.

“I think we need to sober you up before you walk out that door babe.”

“What the fuck is going to sober me up Cameron?” I whine. “It’s not like I’m going a billion blocks down the road. I don’t live far.”

He grabs my hand and helps me stand. “Let’s try to dance a little so we can see how long you stay on your feet.”

Cam leads me to the dance floor. He takes my hand and spins me into him.

My back is to his front while we sway to the music.

The song changes and I lean back into him instantly, stretching an arm to reach the back of his neck. His scent is as intoxicating as the drinks I’ve had tonight. I get so lost in the movement that I don’t realize I’m grinding my ass against him until his hands gripped my hips. I feel his breath on my neck.

“Fuck. Slow down.”

His voice sounds strangled. I turn around to face him. His eyes bore into mine, then they looked down at my lips.

“I really want to kiss you right now Cam.”

Shit. I surprised myself with that one. I slap a hand to my mouth and turn around to walk back to the table. His hand stops me as he turns me to face him again.

Cam brings my hand up to his lips and presses a kiss on my knuckles. “I’ve been wanting you to say that for months.”

I’m stunned to say the least. Even though he’s the most attractive man on the planet, I never thought he’d find me attractive. I’m not usually the type men like him could ever go for. I’m not a skinny girl. I have a stomach and an ass. I probably weigh the same weight as Cam, except his is all pure muscle and I’m just a bigger body. He takes a step closer to me. The way he’s looking at me is sending me into an internal spiral.

“Where’s your brain at baby?”

“Why me?” There’s no way he’s for real right now. I can feel myself start to sober up only slightly. His eyes look at me with what looks like adoration.

“You’re beautiful and you’re kind. I find myself thinking about how genuine and real you are when you’re not around. I feel a real connection to you. And like, you don’t treat me like I’m only a hockey player for the nhl. That’s rare.” He cups my cheek. “I’ve wanted to kiss you for a while now. Jamie will probably hate me for it, but I do.”

I nearly flutter my eyes closed at the contact. “Jamie doesn’t have to know.”

Cam arches a brow at me and he brings his face closer to mine. “He’s ten feet away and I’m pretty sure he saw the away we danced.”

“It wouldn’t kill him to let me have this.”

“I’m starting to agree.”

I let my eyes flutter shut when his lips meet mine. I can feel his smile against my lips. When he goes to pull away, I deepen the kiss. He kisses back with urgency. His arm wraps around my back, tugging me impossibly closer to him. I get lost in him.

My heart is beating out of my chest when I pull my lips from his. He brings his mouth to my ear.

“I’ll tell Jamie I’m taking you home, okay?”

I nod my head and go to pick up my phone and purse. By the time I send the picture to my brother, Cam is back at the table. He takes my hand and we walk out of the bar onto the chilly streets of Philly. My body feels flushed against the wind. My leggings and long sleeved flyers crop top aren’t doing much to save me from the cold. I’m not even feeling cold though. I can’t help but think that I’m about to be alone with him. In my home. I look up at Cam as we reach a street corner.

“What’s going to happen when we get to my place?”

“Whatever you want. I’m not expecting anything if that’s what you’re asking.”

“So if I asked you to stay the night what would the response be?”

Cam stops walking for a moment, pulling me to a stop. “I’ll be honest. I want to.” He slides his hand down my back to rest on my ass and lets out a breath. “I really fucking want to.”

“Good.”

We continue walking until we get to the door of my row house. I fumble with the keys and unlock the door, letting us inside. Cam is looking around my living room. I drop my purse on the couch to get his attention.

“I expected you to be kissing me against the wall by now.” I laugh.

The look of longing flashes across his face. He takes a step closer. I back myself against the wall and he places his body against mine. I’m already consumed by him by just being in his proximity.

“Tell me what I have permission to do.”

“Anything Cameron.” I beg. “Please.”

He presses his lips to my neck, leaving soft kisses. He bites down on a spot close to my ear. My knees almost buckle at the feeling. He pulls away and takes my hands.

“You trust me?”

“I do.”

“Take me to your room.”

I lead him up the stairs to my room. I can tell I’m sobering up more and more every step I take. I’m starting to panic slightly. I don’t want Cam to be just a one night thing. What if that’s what he wants? I bite my lip and turn around when we reach my bedroom door.

“I can hear the gears turning in your head. Like am I doing something wrong?”

“No it’s just- I don’t want this to be a one night thing.” I shake my head and look down. He grabs my chin and lifts it so that my eyes meet his determined gaze.

“You thought this was going to be a one time thing?” He asks. “Let me clarify. I want you. For as long as you’ll have me. Anything else I need to clarify before I open this door?”

“You’re absolutely sure about this?”

“Hell yeah.” Cam’s self control snaps. I’m against my bedroom door and his hands come to my thighs, wrapping them around his hips. I whine in protest against his lips as they meet mine. He pushes open my door and sits me down onto my bed, lifting off his shirt and throwing it across the room. I savored the way his chiseled body looks while I could. His silver cross necklace sits deliciously right against his sternum.

He didn’t miss a beat before his lips attacked mine again. I can feel the scar against my lips. This is heaven. I could kiss him forever. And I think he has the same idea. He barely took his lips off of mine to remove my shirt. I whimper at his taste while my hands go to his pants.

There’s no way we’re stopping now.

By the time I undo the button on his pants, his lips break from mine. I can see his glazed over expression. It doesn’t take him long to push my back to the bed and tug off my leggings. His hands stroke my thighs. He mumbles something under his breath before he leans down to press his lips to the skin of my stomach right above my underwear. His eyes pierce into mine.

“Ready for me?”

I nod my head. He shakes his head back at me. “I need you to use your words baby.”

“Yes Cameron.”

He smirks up at me as he presses another kiss on my skin. “Good girl.”

He takes his time removing my underwear, placing my legs over his shoulders before he sucks my clit into his mouth. His scruff is scratching against my inner thighs. He moans against me and I see stars. I reach a hand down and toss off his hat, tugging on his hair in the process. Sharp pleasure courses through me when he presses two fingers into me. I feel closer and closer to release.

“Cam.” It comes out in a desperate plea. His mouth comes off of me and his thumb rubs circles on my clit. His fingers jack into me at an impossible speed. I let my head fall back and my eyes fall closed.

“Holy fuck I like that.” He moans against me. “Do it again.”

His hook against a spot inside me that makes my vision blur and I moan out his name again. His tongue swirls against my clit and my body tenses. The sensation is so overwhelming that I’m squirming. His arms come around my thighs to hold me still. I clutch his hair as he coaxes me through the most mind blowing orgasm I’ve ever had.

I lay there, breathing hard. Cam’s lips come back up my body and meet mine. While he kisses me I reach down and slide my hand into his boxers. His jeans are still partially on his hips and they slide down further when I wrap my hand around his hard length. His hand catches my wrist as he pulls his head away and groans into my cleavage.

“Next time baby. I won’t last.”

He pulls out a condom and places it on the bed before his hands fumble with the clasp on my bra, removing it along with his jeans and underwear. His cock springs free from its confinements, and my eyes almost pop out of their sockets. The look on his face tells me that he knows he has a weapon attached to his body. Cocky motherfucker knows what he’s doing. I bring my hands up my body to massage my breasts. I hear a frustrated growl come out of him as he lowers his mouth to latch onto my nipple.

He’s so good at this, it’s not even funny. I rock my hips up into his to get some friction and he growls again, taking my other nipple into his mouth. His facial hair is so scruffy that it’s making my skin sensitive. I can still feel the burn between my thighs. I take the condom out of the packet and put it on him.

“I don’t need more foreplay Cam, please get inside me.” I’m begging wholeheartedly at this point. I feel like I might die if he doesn’t fuck me soon. He leans down and bites my bottom lip, gazing into my eyes.

“Is that right?” He smirks.

I roll over and straddle his hips, slowly sliding down onto him. My arms drape over Cam’s shoulders as I moan at how full I feel with him inside me.

“You’re so big.”

Both of his hands take ahold of my ass, smacking and then gripping it. “You’re fucking tight.” He groans and grabs my neck, applying pressure. I whimper at the contact. “I’m going to ruin you for any future guys that might try to take you from me.”

After a moment, I’m grinding into him like my life depends on it. My fingernails scratch down his back and my head falls onto his shoulder, kissing my way down his neck. I scream out when he thrusts up into me.

My body is overfilled with pleasure that I bottom out. Cam flips us over so I’m on my back and he thrusts into me roughly.

I feel like he owns my body. I look at his body and the way it moves against mine. He looks as delicious as he feels inside me. His hand comes back to my neck, applying enough pressure for me to see stars. I clench onto him as he pounds me into oblivion. I call out his name when I reach my peak. We ride out our orgasms together. I connect my lips to his and I feel him empty himself into the condom with a loud groan.

When I drop back to earth, I’m still kissing the most beautiful man to ever exist. He pulls away and I’m still gasping for air. He takes off the condom and tosses it into the trash bin next to my bed before lying down, pulling me back into him to cuddle. My back against his front. He moves my hair away from my shoulder and places a kiss on it.

“I have an off day tomorrow. I don’t know if you have plans but- I mean, I want to take you out if that’s okay,” he mumbles against my skin.

I turn around and peck his lips. “I didn’t climb into bed with you for nothing. I’ll make breakfast in the morning if you take me out tomorrow. Deal?”

He smiles and kisses me again. “Deal. Best girlfriend ever.”

[transgenderer]

so an AM radio receiver can be insanely simple, like foxhole radios

which is amazing! communication through empty space with this incredibly simple device! the razor blade detector acts as a diode, which rectifies the oscillating signal, and the coiled wire acts as a band pass filter so the headphones only get a single frequency

FM radio has way higher bandwidth, so how simple can an FM reciever get? well, this random source claims this is the simplest FM reciever

way more complicated! something here has to be doing a fourier transform but i cant really figure out what. apparently C, T1, T2 L, and R1 form a colpits oscillator, which just produces a constant oscillation(?), tuned to the right station by changing the capacitance on C. apparently the signal is "extracted" on R1? not sure how producing a constant oscillation is supposed to let you extract the frequency modulation. the section for FM radio on the wikipedia article on demodulation lists a bunch of ways its done, so does the article for radio detectors, i THINK this might be a XOR gate detector? but it works by weird inductance stuff where like when you add a signal to a tuned oscillator with a phase difference how much it shifts will depend on the frequency, and then you add them together? idk circuits are very confusing

[narse-tantalus]

People in the notes have a lot of bases covered but I'd like to add:

1) Audiopath. Audio is experienced as an inherently Analog format, and audio quality is determined by the DAC and Amplifier used (assuming transparent digital encoding which is pretty much a given these days). Putting a quality DAC and amp into an earbud is non-trivial and a lot of companies fuck this up. Phones already have DACs and amps. Why pay for duplicate circuits that aren't better? (I can see an argument for dongle DACs ). In general my $80 wired earbuds will sound better to me than using $80 wireless ones.

2) Recharging and batteries: I live out of a backpack or in a van. Having one more battery that needs to be charged is terrible. There would have to be a big positive to offset this downside and there just isn't one for me.

3) Social cue. I like that it's more easily visible to others that I have headphones in. I use earbuds because they travel better than over ears (smaller and lighter) and I want people to know I'm not talking to myself or that I'm not going to hear them.

4) I just hate Bluetooth. (Exception: using it to transfer audio to my van's amp/receiver). I think it's almost always implemented in a shitty way that doesn't do what I want it to do.

5) Antenna functionality (Not supported on my current phone, unfortunately). As recently as 2021 I was using my wired headphones to listen to FM radio on my phone, for free and incurring no data usage, and I think minimal impact on battery life. This was great in Aus where I could get Triple J this way. Was the audio quality good? Not especially, but I enjoyed it a great deal. Listening to local radio is a pleasure when traveling and it's lost when everyone listens to internet streams and when radio stations play the same shit in every country, but you also have to have an FM receiver and antenna to do it. Wired headphones are used as that antenna in phones with FM receivers.

Why do you need your earbuds to have a wire so badly?

I am assuming this is about a post I reblogged like six months ago when I went off on forced technological enshitification and the slow erosion of consumer options. But sure, I'll bite.

Why do I "need" my earbuds to have a wire? I dunno, Anon, maybe I:

Don't want to have to worry about recharging my earbuds.

Don't want my earbuds to be even easier to lose.

Don't want my earbuds to need separate accessories that are as easy to lose as the earbuds.

Prefer to have bluetooth turned off on my devices for security and safety reasons.

Like being able to seamlessly plug my earbuds into my computer, my MP3 player, or any other device with a headphone jack.

Don't want to spend 50 dollars on decent wireless earbuds when I can do all the above things with a pair of solid earbuds that cost me like $12 during the Obama administration.

Don't care about what kinds of headphones or earbuds people wear but don't like what it says about our society when other people apparently care what kind of earbuds I'm wearing so much they have send an Anonymous ask to interrogate me about it.

And I guess, more abstractly, because fuck Apple. That's why.

[atplblog]

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[victoria-hitechpcb]

What is a Rigid PCB?

Rigid circuit board is a common electronic component connection assembly, usually made of non-conductive materials and copper foil and other materials. Rigid PCBs are often used in high-performance, high-reliability electronic devices and are widely used in communications, aerospace, medical and other fields.

Rigid PCBs are those that cannot be bent or folded. Its structure is mainly composed of base material, copper foil and pads. Among them, the substrate can be non-conductive materials such as fiberglass cloth and epoxy resin; copper foil is used to form components such as lines and pads; and the pads are used to realize the connection with other components. Rigid PCBs are usually characterized by high dimensional accuracy, complex manufacturing processes, and high costs, but they are also able to provide higher performance and reliability.

Rigid PCB Uses

Rigid PCBs are widely used in the modern electronics industry, mainly used in the following areas:

Communications field: Rigid PCB can be used to manufacture radio transmitters, receivers, FM televisions, satellite communication systems and other high-performance communications equipment;

Aerospace field: Rigid PCB has light weight, high density, strong shock resistance and other characteristics, to meet the aerospace field of high reliability, high performance equipment needs;

Medical equipment: rigid PCB is used to manufacture medical equipment such as electrocardiographs, blood pressure monitors, thermometers, etc. to ensure the high precision and stability of the equipment;

Industrial control: rigid PCB can be used to manufacture industrial automation control equipment, such as PLC, inverter, etc.;

In summary, rigid PCB is a common electronic component connection assembly, which is characterized by high dimensional accuracy and complex manufacturing process. Rigid PCB can be used in communication, aerospace, medical and other fields, and is mainly used in the manufacture of high-performance, high-reliability electronic equipment. Certain standards and specifications need to be followed in the production process to ensure that its performance and quality reach a certain level.

[teardownit]

The Colpitts oscillator experiment and DIY FM transmitter

The awesome Colpitts oscillator. Exploring the secrets of the Colpitts generator.

Hello, and welcome to our electronic studies! We probably all know that an oscillating circuit consists of a capacitor (C) and an inductor (L), and its waveform is an ideal sine wave.

In the LC resonant circuit, single-frequency oscillations occur, and their period in seconds is equal to 2π√(LC).

This equation is called Thomson's formula after its author, William Thomson, aka 1st Baron Kelvin. Many other things are named after him because Lord Kelvin was an outstanding scientist and inventor. One can recall, for example, the Kelvin, a unit of absolute temperature, or the marine compass with sundial he invented.

Another thing we know is that a transistor and an operational amplifier amplify the signal, meaning they transform a sin wave with a small amplitude into a sine wave with a bigger amplitude. We had 0.5 volts; it became five volts - ten times as much.

However, real electronic devices, even seemingly simple ones made from a handful of components, work in a much more complex and interesting way than the simplified idea of them from a school physics class.

This can either cause problems that we must learn to overcome or inspire technical creativity and help us achieve difficult tasks with simple components.

Today, we will study the operation of a real Colpitts oscillator, and a small printed circuit board and a digital oscilloscope will help us with this.

Edwin Henry Colpitts was a great inventor and a famous communications engineer. From 1897 to 1899, he served at Harvard's Jefferson Physical Laboratory. From 1899 on, Mr. Colpitts worked at the American Bell Telephone Company. In 1907, he became the research branch chief at the Western Electric Company. It was a manufacturing division of the American Telephone and Telegraph Company from 1881 to 1995.

Colpitz became vice president of AT&T in 1924 and was vice president of Bell Labs from 1934 to 1937. From 1940 to 1946, he served as head of technical aid for Division 6 (antisubmarine warfare) of the National Defense Research Committee and was awarded the Medal of Merit.

As often happens among renowned geniuses, Colpitz neglected his most known invention. He described the operating principle of his generator in a private conversation around 1915. He quickly forgot this product pitch, and later, according to company practice, he was asked to sign a patent application in 1918 (US patent 1624537).

A distinctive feature of the Colpitts oscillator is that the positive feedback for the amplifier (which can be a bipolar or field-effect transistor, an operational amplifier, or a vacuum tube) is received from a voltage divider on two capacitors connected in series and connected to an inductor.

The oscillation frequency is nearly equal to the resonant frequency of the LC circuit of two capacitors with an inductor parallel to them.

The actual frequency will differ from the theoretically calculated one due to the distribution of capacitances and the resistive load of the transistor. This is exactly what we will see on the oscilloscope screen.

The twin brother and probable predecessor of the Colpitts generator was the Hartley oscillator; a patent application for it was filed in 1915 (US patent 1356763, issued 1920). The difference is that a voltage divider for positive feedback is formed not by two capacitors but by two inductors in series or a single-tapped inductor.

The innovative feature behind the Hartley oscillator was that its coils did not have to be magnetically coupled, which was strictly necessary for its predecessors, the Meissner and the Armstrong oscillators.

Rhodes Scholarship winner Ralph Vinton Lyon Hartley, also known for pioneering the concept of "information" as a random variable and for attempting to define the "unit of measure of information", has worked for the Western Electric Company since 1915. He was in touch with Edwin Colpitts at the time and probably was a part of the aforementioned discussion on using a capacitive voltage divider instead of an inductive one.

Hartley was awarded the IRE (now IEEE) Medal of Honor for his generator and information proportionality law in 1946. In addition to the oscillator, Hartley transform, and the logarithmic unit of measure for information entropy named after him, he owns more than 70 patents, including a neutralization circuit to eliminate parasitic self-excitation of a triode.

The very first IRE Medal of Honor in history was received by the inventor of the LC continuous oscillation generator with positive feedback (differing from the earlier shock excitation of damped oscillations, like the Hertz generator and Tesla spark transformer).

The idea of positive feedback was also introduced by American electrical engineer and innovator Edwin Howard Armstrong, inventor of the FM radio, superheterodyne and super-regenerative radio receivers, and FM radar. In total, Armstrong filed 42 patents.

The Armstrong oscillator, made in 1912, was an LC resonant tank circuit connected to the input of a tube or transistor amplifier stage. A feedback coil was connected to the output of the cascade.

The generator, invented in 1913 and named after Austrian engineer and physicist Alexander Meissner, was similar to the Armstrong generator; the only difference was that the Meissner LC generator circuit was connected to the output of the amplifier. The coupling coil was connected to the input. These two oscillators were so close that they are now often combined under the general name "Armstrong-Meissner oscillator".

Each of these generators must be carefully tuned to produce a clean sine-wave signal. We will now see this during the experiment. An oscilloscope can show more than a dozen formulas.

In today's experiment, we will make use of a board designed for a middle school experiment. It contains a Colpitts oscillator on transistor Q1, an amplifier stage on transistor Q2, a reversed-phase amplifier on op-amp U1A, and a node on operational amplifier U1B, which can be a comparator or an analog signal amplifier, depending on the setting.

The operational amplifiers are powered by a bipolar ±9-volt power supply. At the same time, the transistor stages only need a unipolar + 9 volts of power.

DC isolation is provided by capacitors C5, C6, and C7, which pass the alternating component and block the direct current one. This way, it is possible to transmit an alternating electrical signal between circuit points with different potentials. This is one of the fundamentals of electronic circuitry.

Capacitor C1 grounds the AC base of transistor Q1, so the cascade operates in common-base mode. Resistor R1 (or R2, we can switch between them using jumpers JP1 and JP2) sets the bias current of the base of the transistor and thus its operating point.

The oscillating circuit coils are switched by jumpers JP3 and JP4, capacitors C2 and C3 by JP5 and JP6.

In total, we have two to the power of three, that is, eight options for jumper positions. Let's start from the very first: close JP1, JP3, and JP5. Next, we will switch one jumper at a time to see the changes at each stage until we've tested all eight possible combinations.

Let's take another look at the formula for the oscillation frequency of the Colpitts generator. The calculated oscillation period is 2π√(0.1 mH * 5 nF) = 4.44 ns. This corresponds to a frequency of 225 kHz.

Inductance L2 exceeds L1 by 4.7 times, which should reduce the frequency by √4.7 = 2.17 times. The capacitance of C3 is 3 times higher than that of C2, so we should expect a decrease in frequency by √(0.75/0.5) = 1.22 times.

Let's connect the oscilloscope to the node TP2 output of the generator. The measured frequency when C = 0.01 uF and L = 100 uH turned out to be 314 kHz; the calculated frequency is 30% lower. The cause could be Chinese-made ceramic disk capacitors; cheap ones tend to have 30–35% less capacity than listed. The oscillation amplitude Vp-p is 3.92 V, while the sinusoid is not ideal with a flattened lower part.

We did not replace either capacitor or inductor; we just switched the transistor base bias resistor from 10 to 220 kOhm. Now we have a beautiful sine wave with an amplitude of 4.44 V. And the most interesting thing here is that the frequency has decreased to 301 kHz.

The fact is that the base bias current changes the conductivity of the transistor and, accordingly, the equivalent capacitance, which defines the resonant frequency of the oscillatory circuit. This property of a transistor LC oscillator will help us build a simple FM radio transmitter.

After connecting a 0.03 uF capacitor, the oscillation frequency dropped by 20% to 243 kHz, which fully correlates with the calculations. The amplitude has dropped to 2.6 V. The waveform is distorted; the sine wave is now modulated with a half-frequency signal. Each odd half-wave is twice the amplitude of the even one.

Switching back to the 10 kOhm resistor, we see the frequency increase to 263 kHz. The amplitude dropped even lower, to 2.28 V, but the sine wave is now flawless: symmetrical and not flattened at the bottom.

Connecting the 470 uH inductor, the amplitude is 2.28 V. The frequency of 121 kHz is exactly 2.17 times lower than 263, which fully corresponds to the formula.

With a 220 kOhm resistor, the frequency dropped to 54.3 kHz. The minus-first harmonic has now become stronger than the design frequency of the generator. So, we got the frequency divided in half, and the fundamental frequency now becomes the first harmonic. The amplitude increased greatly to 4.9 V.

With a 0.01 uF capacitor, the voltage increased to 7.28 V. The sine wave looks right, and the frequency is correct—133 kHz.

With a 10 kOhm resistor, the amplitude dropped to 4.52 V, and the frequency increased to 145 kHz. The lower part of the sine wave is squashed.

To look further into the signal propagation, let's revert to the 220 kΩ resistor because this combination produced a stable and strong signal with an ideal sine wave shape. Now, let's see the distortion caused by the transistor and operational amplifiers.

We see extreme distortion on collector Q2. Not only did full-wave rectification of the signal occur, but a third harmonic, characteristic of transistors, was also added. It shows up as a hump one-third of the period wide. Such odd transistor harmonics are undesirable for the resulting sound, unlike tube harmonics.

Such strong signal distortion is caused by the scheme with a common collector and not with a common collector. If we connected a capacitor in parallel with R6, we would get a common-emitter stage, and the signal at the collector would be much cleaner.

On the contrary, we see an excellent pure sine wave at the emitter because Q1 operates in buffer mode or emitter follower.

Now, let's connect the oscilloscope probe to the output of the first operational amplifier, U1A. And instead of a sinusoid, we see relaxation oscillations, the pattern of which changes depending on the resistance of the trimming resistor RP1 in the feedback loop.

C6 and R7 are differentiator circuits or high-pass filters; their time constant is 1 millisecond. And the period of oscillations at a frequency of 133 kHz is 7.5 microseconds, which is 133 times less. Therefore, this RC chain has almost no effect on the signal flow at this frequency.

Where do the distortions come from, then? We haven't added a small ceramic capacitor parallel to RP1 to the circuit design. Several tens of picofarads of capacitance would've helped suppress the high-frequency resonance of the operational amplifier.

Finally, at the output of U2A, we see either a constant voltage or an almost perfect triangle wave, depending on the resistance of RP2. In the first case, U2A works as a comparator, and in the second, as an amplifier, thanks to the resistor R13 creating negative feedback.

The fact that the Colpitts oscillator frequency depends on the transistor base bias current was used in a small FM radio transmitter that I've assembled and tested. Experiments with it do not violate the laws on radio communications, as its power is extremely low. Transmitters like this are used in older cars to listen to music from a CD or MP3 player through an FM radio that does not have an AUX input.

Q1 amplifies the microphone signal, which then goes to the Q2 base, part of the Clapp oscillator. This is almost the same Colpitts generator, with an added capacitor C8 in series with the coil L4 to improve operating stability.

Q3 works as the output power amplifier. C7, C9, C10, and L3 together are the output filters for frequency matching with the antenna, which is just a piece of wire.

The input jack disconnects the Clapp oscillator from the microphone amplifier and supplies a modulating signal from an external source. For example, a homemade MP3 player, like in my video.

The left channel signal comes through resistor R10, and the right channel comes through resistor R7. This is a mono transmitter. I also plan to assemble a stereophonic modulator and tell you all about it in one of the upcoming posts.

[g-nicerf]

Understanding the Dynamics of the 433MHz RF Transmitter and Receiver

The realm of wireless communication has been punctuated by several pivotal technologies, but among them, the 433MHz RF transmitter and receiver system stands tall. These components are quintessential in bridging the gap between devices, ensuring that signals are sent and received with utmost precision. With a focus on the 433MHz spectrum, this article delves deep into the mechanics, applications, and the future of the RF transmitter and receiver systems.

In the world of radio frequencies, the 433MHz range, earmarked for the RF transmitter and receiver, is part of the UHF (Ultra High Frequency) band. What sets the 433MHz RF transmitter apart is its ability to transmit data over considerable distances without significant loss. This is aided by the receiver, which is precisely tuned to capture these signals, thereby maintaining the integrity of the transmitted data.

The beauty of the 433MHz RF transmitter and receiver lies in their symbiotic relationship. The transmitter's primary role is to modulate an input signal and then radiate this signal as electromagnetic waves. On the flip side, the receiver’s job is to detect these waves, demodulate them, and reconstruct the original input signal. Together, this RF transmitter and receiver pair ensures a seamless and efficient communication process.

Beyond the basic mechanics, there are various modulation techniques that the RF transmitter and receiver can employ. Techniques like Amplitude Modulation (AM), Frequency Modulation (FM), and Phase Modulation (PM) are just the tip of the iceberg. Depending on the application and specific requirements, these techniques can be utilized to enhance signal clarity, reduce noise, and improve overall transmission efficiency.

In real-world applications, the relevance of the 433MHz RF transmitter and receiver is undeniable. They're found in numerous systems, from home automation setups to industrial telemetry. Whether you're using a remote control to adjust your television settings or an industrial sensor is transmitting critical data across a plant, it's the RF transmitter and receiver that make these operations possible.

Furthermore, as technology evolves, so does the potential of these systems. With advancements in integrated circuits, digital signal processing, and antenna design, the performance of the RF transmitter and receiver is continuously improving. This translates to greater ranges, better signal clarity, and the capability to handle more complex data structures.

In conclusion, the 433MHz RF transmitter and receiver stand as pillars in the wireless communication domain. Their symbiotic relationship, combined with advanced modulation techniques, positions them at the forefront of technological innovation. As industries grow and wireless communication demands expand, the role and potential of the RF transmitter and receiver will only become more pronounced, reinforcing their indispensable nature in our interconnected world.

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[greatworldwar2]

• SCR-300 Radio

The SCR-300 was a portable radio transceiver used by US Signal Corps in World War II. This backpack-mounted unit was the first radio to be nicknamed a "walkie talkie".

In 1940, Motorola (then the Galvin Manufacturing Company) received a contract from the War Department to develop a portable, battery powered voice radio receiver/transmitter for field use by infantry units. The SCR-300 operated in the 40.0 to 48.0 MHz frequency range, and was channelized. Along with other mobile FM tank and artillery radios such as the SCR-508 (20.0 to 27.9 MHz) and the SCR-608 (27.0 to 38.9 MHz), the SCR-300 marked the beginning of the transition of combat-net radio from low-HF AM/CW to low-VHF FM. The SCR-300 was an 18-tube battery operated radio transceiver. It used an FM transmitter section and a double superheterodyne receiver. It incorporated a squelch circuit, an automatic frequency control circuit, and a crystal controlled calibration circuit. The SCR-300 had a range approximately of 3 miles (4.8 km).

Although a relatively large backpack-carried radio rather than a handheld model, the SCR-300 was described in War Department Technical Manual TM-11-242 as "primarily intended as a walkie-talkie for foot combat troops", and so the term "walkie-talkie" first came into use. The final acceptance tests took place at Fort Knox, Kentucky in Spring 1942. The performance of the SCR-300 during those tests demonstrated its capacity to communicate through interference and the rugged quality of the design. Motorola was to produce nearly 50,000 of the SCR-300 units during the course of World War II.

The SCR-300 saw action in the Pacific Theater, beginning in New Georgia in August 1943. Colonel Ankenbrandt informed General Meade that "they are exactly what is needed for front line communications in this theater". The SCR-300 saw heavy use in the Normandy invasion and the Italian campaign. It also became "key equipment" that helped deter confusion in the Battle of the Bulge. The British adopted the design of the SCR-300 for their own use from 1947 as the "Wireless Set No. 31".

[silverdanilleann]

A Short History About Communication frim Cave Drawings to Web

How do we communicate in the past?

Other forms of early communication existed, although they were less popular for a variety of reasons. Story telling was used to pass on important information in the days before the existence of the written word. However, since man still lived in separate tribes, this information could not be applied outside one’s own tribal community. 

Early handwritten Document Books

Istiqamantunnisak | https://unsplash.com/photos/-VwEu9GnyPU

📜 People who receive proper education can only handwrite books

📜 manuscript came from the Latin world "libri manu scripti" which means book written by hand"

📜 majority of books were written for religious purposes

📜 literacy rates were incredibly low.

📜 on 13th century secular books were produce for the sake of spreading knowlede not related to religion

Printing Press

https://www.google.com/amp/s/amp.interestingengineering.com/the-invention-and-history-of-the-printing-press

🖨️1448, a man named Johann Gutenberg invented the printing press

🖨️this method allowed books to be mass-produced, and greatly reduced the price.

🖨️Gutenberg made his first device by adapting a wine press to remove the water from paper after printing

🖨️the printing press took awhile to catch on, as the bourgeoisie of the day still wanted to keep the peasants uneducated.

Letter Writing and the Postman

Museums Victoria | https://unsplash.com/photos/HLvV5_BLs_k

📬it was an inefficient means of communicating as one had to wait until another person was traveling before their letter could be sent.

📬there was no guarantee when, or if, the letter would ever reach its destination.

📬on 1800s the system caught on quickly and rapidly expanded

📬mail was transported primarily by train, which ran on a schedule and was efficient and reliable

Telegraph

📌The logistics of telegraphic communication involve the sending of electrostatically-generated signals through a wire

📌The revolution of the telegraph allowed for instant communication across long distances, something that had previously been unheard of.

📌the system involves three main components- a battery to supply the electricity, a key used to complete or break the circuit, and an electromagnet at the receiving end which consists of a wire that pulls on a piece of metal when electricity passes through it.

📌it was invented by Samuel F.B. Morse

https://www.istockphoto.com/photos/morse-code?mediatype=photography&phrase=morse%20code&sort=mostpopular

Telephone

Himanshu Ranpara | https://unsplash.com/photos/uXuXXHDgMdM

☎️in 1876, Alexander Bell was busy realizing a dream that he hoped would once again revolutionize communication.

☎️Bell observed that sound vibrations could be transmitted through the air, and received at the same pitch in another room.

☎️Bell’s invention was initially quite unpopular.

☎️The telegraph had cornered the long-distance contact market.

☎️The lack of popularity may also be attributed to the cost of telephone service.

Radio

📻What began as short-wave communication used during WWI blossomed into the hottest communication technology of the era once the war had ended.

Csongor Schmutc | https://unsplash.com/photos/WximLTzm94E

📻Radio was unregulated until 1925 when the Federal Communications Commission stepped in.

📻The technology really took off in 1933 when Edwin Armstrong, “the father of FM radio”, invented frequency-modulated radio.

🖼️Capturing an image of the self guarantees a place a in history for that individual.

📻By the 1940’s, the number of radios in American homes had doubled, and 800,000 FM receivers were produced in 1947.

Photography

Laura Furhman | https://unsplash.com/photos/73OJLcahQHg

🖼️The first attempts at photography began in the early 1800’s but had poor results. The discovery of using reverse colors, what we today call a “negative”, greatly advanced the art of photography.

🖼️The process of how a photo was taken and developed remained largely unchanged for 150 years until digital technology caught up.

🖼️These days a piece of equipment that was once used only by professional photographers is accessible to everyone.

Television

Peter Geo | https://unsplash.com/photos/pFfZDaTVdtc

📺Television made its official debut at the 1939 New York World’s Fair.

📺It was seen as an amusing, but unnecessary, appliance and the radio continued to be the favored form of communication.

📺All that began to change in the late 1940’s.

📺As the years passed, prices for televisions dropped and now the majority of homes have at least one television. It is safe to theorize that few forms have communication have had as large an impact on society as television.

Cell Phone

Eirik Solheim | https://unsplash.com/photos/pFfZDaTVdtc

📱It may be hard to believe but the first cell phone research began in 1843 when Michael Faraday conducted research to see if space could conduct electricity.

📱Fast forward to1973, and Dr. Martin Cooper is credited with inventing the first portable handset. Four years later, cell phones go public.

📱In the 37 years the cellular phone industry has existed, the market has grown from $3 million annually to an industry that commands $30 billion annually.

📱Landlines are slowly becoming obsolete as everyone from senior citizens to elementary school students acquire their own cell phones.

Internet

Matthew Guay | https://unsplash.com/photos/Q7wDdmgCBFg

📶The original Internet was invented in 1967 for military purposes.

📶An Internet in its most basic form is simply a group of computers able to connect to each other and share information. This included electronic mail (email) and the use of sites containing vital information (websites).

📶It has even surpassed the television as a source of communication because you can receive any information you want instantaneously.

📶Today the Internet is available everywhere and to everyone. It is used for a variety of reasons including socializing, conducting research, and advertising.

Read more here https://www.google.com/amp/s/www.creativedisplaysnow.com/articles/history-of-communication-from-cave-drawings-to-the-web/%3famp

[asoundimagination]

Two Pieces (it’s a start).

They say you should “write what you know,” so I figure a short discussion of my own, recent work is as good a place as any to start. That said, in sticking with my own philosophy on the matter, I should point out that for me writing music is not so much a vehicle for delivering a message as it is for receiving a synthesis of knowledge and illumination from the creative process. I don’t ever really feel that my music means anything in particular, or has encoded in its structure some special meaning that will be apparent only to an initiated few (the classic “you have to know the following things in order to understand it” routine).

I think of composing as the creation of catalysts for potential meaning. This is achieved in response to our creative impulse by molding the ether of inspiration with craft and purpose through cognizant choices, and allowing our work to be infused with limitless variations of meaning by those who enter into communion with the results of those choices. This special communion could be the execution of a performance of the work, the experience of seeing and/or hearing the work performed, a study of the work on paper or through dialog or some combination of these manifest scenarios.

In other words, I am much more interested in what I stand to learn from my work (about myself, the world, creation), than in making some presumption that I have anything particularly profound to tell anyone. Even if there were a standard set of tools with which one could—with relative conformity—decode so abstract a medium as sound, we would be left then to decipher the inherent limits and inadequacies of descriptive language. (Thoughts on experiential versus intellectual understanding reserved for another time).

This viewpoint sometimes throws me into a dilemma that is agitated when someone asks the inevitable question, “Oh! What kind of music do you write?” I don’t think I’m qualified to know or answer in a meaningful way, and as soon as we think we are we have stopped allowing ourselves to think creatively.

Indeed, while inspiration informs the work, I don’t think we need to say that what inspired it is what the work is about. Inspiration is not a molecular structure that is meant to be transmitted and received from the material itself, nor can it objectively be heard there without copious explanation or justification by the composer. I think: being told what you’re supposed to hear in a piece of music (or, let’s say, see when you interact with a work of visual art) subsequently limits its real potential for meaning and possible depth of substance. It is an exclusionary and perhaps elitist practice, and in many cases serves more as a failsafe against a work’s lack of honesty and quality than a legend to inspire understanding.

To popularly quote Miles Davis, “If you understood everything I said, you’d be me.” It is easy to cite profound examples in creatively ascended individuals like Ornette Coleman, whose struggles with notation and language never allowed him to completely articulate what may have simply been inexpressible concepts in his work; gossamer bonds strung between points in the constellation of space, performers, instruments and other factors that enveloped the performance of each piece, whether in the recording studio or on the stage. Context defined the expression of the work. (See Coleman’s fluidic use of the word “unison” when imploring his collaborators to bring themselves to the music in ways the charts could not indicate).

For me, inspiration exists in parallel with the work it inspires. It compliments it, resonates with it, allows for its existence but it is not material or elemental in the new work’s particular, phenomenological dimension. It is there like the memory of a dream. While the dreamer may do their best to explain the setting, events and emotional atmosphere they experienced—distorted by the entropy of memory recall and the limit of their savvy for description—the dream falls away as a separate object and the description emerges as something new and unique.

Just as Coleman’s concept of unison served to ignite spontaneous collaborative energy that could be heard in the work if not pinpointed in theoretical terms, perhaps the source of a work’s creation need only be a footnote to inspire further reading, rather than a frontispiece that makes claims about what it is in advance. It should be information that beckons the listener to rise to a new level and expand their perspective, rather than an immutable, Platonic archetype that condescends to us uninvitingly.  

Imagine then if we could each experience the same dream, and then upon waking explore its substance through discourse and reflection. The basis or topic of the dream’s narrative would serve as a reference used to enhance the experience we take away, in combination with the experience we brought with us.

So, presented below and absent of any implied inherent meaning are my two most recent pieces, with brief descriptions of their various, inspirational references.

“Complete Silence: Dream Music - 完全な沈黙: 夢の音楽” is a twenty-five minute triptych of sonic meditations that mixes simple, lo-fi synthesizer sounds with spacious field recordings. The title is inspired by a mysterious Twitter post by @archillect-aesthetic made sometime in 2019 that showed the phrase "complete silence" in white Japanese lettering on a black background, likely a screen capture from an old Japanese film.

The titles 'Vedic Hymn' and 'Themes for an Aztec Moralist' (the inner and outer movements) are borrowed from the great Mexican poet and Nobel Prize laureate Octavio Paz (1914-1998), while 'Totemic Self-Portrait' (the central movement) is taken from a paper on Outsider Art by Roger Cardinal [“Toward an Outsider Aesthetic,” 33-34]. In this case, Cardinal's analysis was being referenced by Emily Olson (2008) in her own paper on the surreal paintings of Mexican outsider artist Enrique Chavarría (1927-1998), to whom the track owes its inspiration.

Gear: MicroKorg, DigDugDIY Waifu Reverb, Deadbeat Echolocation Station, DOD Gonkulator Ring Modulator, Novation Circuit
, Tibetan Bowls, Antique Clock Chime, Loose Change, Glass Jar.

'_planète sauvage' is a seven track, twenty-seven minute EP, the title of which is taken from the iconic, animated film of the same name by René Laloux (1973). This work is a collection of small and minimal pieces inspired by infinite solitude, primordial isolation, Cyclopean mental structures and the impossibility of imagining or comprehending alien concepts, even when confronted by them.

Tracks 3 and 6 sequentially use the title, "Hymns of the Bene Gesserit" and are made in homage to the fantastic world of Frank Herbert's DUNE.

Gear: MicroKorg, DigDugDIY Waifu Reverb, Deadbeat Echolocation Station, DOD Gonkulator Modulator, Korg Volca FM Synthesizer, Novation Circuit, Michael Rucci Maximal Drone

Cover Image Credits: ESA/Rosetta/MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

[akshayparkinson-blog]

Techniques For Picking the Best Wireless Audio Transmitter Product For Whole-House Audio Streaming

Progressively more wireless audio transmitter products promise the best freedom in streaming music throughout the house. We are going to examine different products and technologies to determine in how long these items are helpful for whole-house audio applications as well as what to watch out for when purchasing an invisible system. Running music within your house is usually a daunting task. Many homes are not wired for multi-room audio and getting the music from the lounge on your bedroom is usually a challenge. Items which solve this concern are often in line with the following technologies: infrared wireless, RF wireless, wireless LAN or powerline. Infrared wireless audio items are restricted to line-of-sight applications, i.e. only operate inside a single room considering that the signal is distributed as infrared light which cannot penetrate walls. Fractional treatments is often seen in wireless speaker kit products. RF wireless audio products send the audio signal via radio waves. These radiation signals can certainly experience walls. The signal is distributed either through the use of FM transmission or digital transmission. FM transmitters are the most affordable option. They feature good range but the audio signal is at risk of audio distortion and noise and is also very vulnerable to interference business wireless transmitters. Digital wireless audio transmitter products utilize a digital protocol. The audio is first transformed into digital data before being transmitted. This technique makes sure that the audio quality is fully preserved. Some transmitters apply certain kind of audio compression, such as Bluetooth transmitters, that can degrade the audio rather. Transmitters which send the audio data uncompressed will reach the highest fidelity. Products using wireless LAN are useful when streaming audio from the PC. Their drawback is that they typically have some fairly high latency, i.e. the signal will likely be delayed by a few amount since wireless LAN had not been created specifically for real-time audio streaming. Also, some products require to buy separate wireless LAN modules which are connected to each audio receiver.

Powerline products send the audio through the power mains and give great range. They encounter problems in houses where there are separate mains circuits when it comes to being able to overlap into another circuit. Also, they build inside a delay of countless seconds to shield against transmission errors during harmful electrical currents and spikes which prevents their use in applications in which the audio from wireless stereo speakers must be in sync along with other non-wireless speakers or video. Below are great tips for selecting a wireless speakers: If you plan to stream audio into several rooms of your house, be sure to go with a system that allows streaming to multiple receivers as well. This way you don't have to purchase a separate transmitter for every receiver that you will be streaming to. Some products involve some kind of error correction internal that helps guard against dropouts in case of strong wireless interference. Look for a digital RF audio transmitter to ensure that the audio quality is preserved. Ensure that the audio latency is less than 10 ms in case you have a real-time application for example video. Go with a transmitter containing every one of the audio inputs you need, e.g. speaker inputs, RCA inputs etc. Pick a system which you could add receivers at a later date which offer each of the required outputs, e.g. amplified speaker outputs, RCA outputs etc. If you go with a digital audio transmitter, choose one with an input audio level control knob in order to avoid the audio signal from clipping inside the transmitter audio converter. This can ensure optimum dynamic range regardless of the signal degree of your equipment. Check that the amplified wireless receivers have built-in digital amplifiers with low distortion figures. This may keep the receiver cool on account of high amplifier power efficiency and provide optimum quality of sound. Guarantee the receivers can drive speakers with your desired Ohm rating. Deciding on a product where the wireless receivers possess a small footprint and simple mounting options will help through the installation. Products that operate in the 5.8 GHz frequency band may have less problems with wireless interference than products using the crowded 900 MHz or 2.4 GHz frequency band. To get more information about best bluetooth transmitter site: visit site.

[speakerhospital]

Amplifier Repair: Step by Step Guide

Do you know how to do amplifier repair? The complexity of an amplifier repair usually relies on malfunctioning parts and their location in the unit. Many things can go incorrect with your amplifier, but common problems will likely affect all brands and models. The main components include a speaker, power amp and preamp. The preamp is the part that transforms the audio signal into an electrical current. Your amplifier receives the electrical currents from the preamp, adds voltage, and sends the signal to the speakers. This is the function of the amplifier and below mentioned are a few steps to repair the amplifier:

What is an amplifier?

It is an electronic device that magnifies and controls the output of audio signal sources from audio home entertainment devices like an external CD player, tape player, or built-in AM-FM receiver. The output signal is normally fed to audio speakers. As mentioned, the main components include a speaker, power amp and preamp.

The amplifier works step by step

An amplifier accepts an input signal from a reference, such as a laptop or CD player. It generates a larger copy of the original signal before sending it to the speakers. It obtains the power to do this from your main electricity, which is sent directly to the power supply within the amplifier.

Why do amplifiers fail?

Speaker load and amplifier failure are the two things. One of the major reasons that amplifiers fail is improper speaker connection. If too many speakers are associated with an amplifier, the amplifier will be more likely to fail.

Repairing an amp: step-by-step

Here is an easy step by step guide on how to repair an amplifier:

Step 1

The primary step involved in amplifier repair is turning off the amplifier and allowing it to cool down. Once it cools down, turn the volume to zero.

Step 2

Then, turn the amplifier on. If the LED that shows 'ON' lights up, there is no problem with the power supply. Try to function normally by turning up the volume. If you receive some sound that is too low or poor quality, the amplifier is working but not to its finest level. A loose connection may cause this. If no sound is produced, a part of it is likely broken.

Step 3

You may use a screwdriver to screw the back panel of the amplifier. Eliminate the chassis to expose the circuit board. Then, check for obvious signs of damage like a blown fuse or transistor. Then you will come to know a fuse or transistor is blown when you look for a brown discolouration. If that is the case, replace either part with an identical part.

Step 4

Also, you can examine to see if there are any loosely interconnected wire joints. You can do this by outlining the circuit wiring from input and slightly pulling on the wire. If the wiring is slack, then there will be a loose connection. You can re-establish the link by melting the loose wire joints and soldering them.

Step 5

Inspect the printed circuit board and look out for loose-fitting capacitors and resistors. When one of these parts comes missing from the circuit, the circuit is shorted. Once a resistor is no longer executing its job of regulating current, the entire circuit fails.

Step 6

In this step, you can test the resistors by placing your voltmeter probe directly after the first resistor in the signal chain. After that, set the meter to "resistance" and power up the amplifier. Each resistor has its unique value printed on the side. Once you power up the amplifier, the voltmeter should show a reading within a 5 per cent modification of that value. If it is beyond this variance, the resistor is malfunctioning. If it is zero, the resistor is entirely shorted.

Step 7

After turning off the amplifier and replacing the resistor, separate the solder joint on the bottom of the circuit board and remove the resistor. Solder in an exact replacement.

Step 8

The final step is to test the output transformer. Use a screwdriver to unscrew the transformer's housing so that you can picturise the primary winding. Attach a meter to the winding inside the transformer, then turn the amplifier on. It would help if you got an almost similar analysis to the power handling detailed in your user manual. If the meter reads zero, the transformer coil is shorted, and an overly high reading means the transformer is leaking. In both cases, you want to replace the transformer.

Final thoughts:

Before you learn how to repair an amplifier, whether a stage or fender amplifier, you must know its build and operation, there is no guarantee that your guitar or bass practice amp will never have issues. Therefore, it is significant to know amplifier troubleshooting and repair tips. The above listed are some of the steps and tips you may need for an amplifier repair whenever it stops functioning properly.

Disclaimer: This is a generic Information & post; content about the services can be changed from time to time as per your requirements and contract. To get the latest and updated information, contact us today or visit our website. 

[ka7v]

Joe Taylor’s Amateur Radio by Barry Wright - KA7V With Input from SM2CEW

At one time the history of the American Radio Relay League (ARRL) and its creator Hiram Percy Maxim were always mentioned prominently in the ARRL Handbook. This is no longer the case. You may do a search on any recent edition and see what you find.

Mr. Maxim was the individual that founded the ARRL in 1914 and profoundly influenced what amateur radio is today. The most important mode of communication at the time was continuous wave or CW. This is commonly known as the Morse Code invented by Samuel Morse. When I obtained my first amateur radio license in 1958 the ability to send and receive the Morse Code at 13 words per minute was a requirement for obtaining a license. The most common license at that time was the General Class License and it provided all privileges for amateur radio operation.

Amateur radio operation was not unique to the United States and was and remains to this day popular all over the planet.

As some point during the 1970s the ARRL decided that to operate on all modes on all bands a higher status license was required. This was the Amateur Extra Class license. To obtain this license one had to demonstrate knowledge of radio frequency communication including electronic fundamentals and all of the rules and regulations that were required to legally operate an amateur radio station. In addition, the Morse Code requirement was set at 20 words per minute. Since I had operated CW almost exclusively during my amateur radio career, 20 words a minute was not a problem. The technical exam for the Amateur Extra Class License in 1980 was comprised of multiple choice questions. When I first obtained my license in 1958, this wasn’t the case. At that time, one might be asked to draw the circuit diagram for a Colpitts oscillator or define the differences between Class A,B, AB and C transmitter operation. These classes of operation were defined as their conduction state. You can find a lot of information on amplifier conduction states on the internet.

I will say that Class A amplifiers were considered linear where the single output device conducts through a full 360 degrees of the output waveform. When one is listening to recorded music, for example, this was considered ideal. However for operating radio transmitters, the efficiency of Class A operation was not very high and greater amplification of a transmitted signal was needed. A form of linearity was still considered desirable however, especially for voice communication. One could run CW operation in Class C. These were non-linear modes and were most suitable for CW and similar modes like RTTY and frequency modulation or FM. Again if you want more information about this subject matter, the internet is full of such material.

These techniques were accepted from the beginning of radio frequency operation through the end of the 20th Century. I saw no need for anything else.

There were additional codes besides CW that were employed by governments, for example, that wanted the content of their communications kept secret. During the 2nd World War, the Germans and Japanese both had encryption algorithms that made it difficult to easily decipher their messages. The United States military could translate the Japanese code into understandable English and the Allies did the same for the code used by the Germans.

There were algorithmic requirements for these codes or they would be so simple to translate that they would become useless for any method of encryption. The Morse Code on the other hand was simple to the point where a moderately intelligent individual could easily translate CW into English words themselves.

Modes like RTTY or Radio Teletype and psk31 had a level of complexity that made it difficult if not impossible to translate without the assistance of a decoding device. Decoding devices are now known as computers.

So there were several modes of operation for amateur radio operation but it was still necessary to be able to send and receive the Morse Code to obtain an amateur radio license that granted all operational privileges. The assumption by many was that the technical aspects of any exam could be memorized from a text book but one couldn’t fake knowledge of CW. CW was the ultimate indicator of anyone’s acceptability to join the amateur radio community.

The importance of CW can be seen in this example. One of the great achievements of radio communication was the reflection of a radio signal off the moon and its reception back on the earth. This was first done by the U.S. Army on January 26 1946 and was later done by amateur radio operators. You can read more about the amateur radio moon reflection project here:

The first Amateur Lunar tests & contacts.

It became easier over the years as amateur radio operators accumulated wealth and antenna and preamp design became more sophisticated. By the early 1970s many amateur radio operators were able to send and receive signals via “moon bounce” or earth-moon-earth (eme). This was first accomplished by Morse Code. So Morse Code once again was essential to amateur radio.

For some reason however the Federal Communications Commission, with the suggestion and support of the corporate lobby previously known as the American Radio Relay League, removed all Morse Code requirements for all amateur radio license classes in 1991. You can read about their pathetic excuses in this piece: It Seems to Us “Morse” by David Summer.

There were members of the amateur radio community that did not think this was a good idea. See, for example: Maybe Nothing Will Save Amateur Radio - Original Author Unknown

After all, for amateur radio to remain a civilized process some degree of proficiency in a set of skills was necessary. I can only speculate why the ARRL lobbied the FCC to take this step in reducing the requirements for obtaining an amateur radio license, but the general assumption was that the ARRL wanted the number of amateur radio operators in the world to increase. It is perhaps coincidental that the greater number of amateur radio operators that existed, the larger the market would be for amateur radio equipment.

Well since making legitimate contacts by modes such as single sideband could still at times be difficult, a new mode of communication that had a much higher probability of success was desirable. After all, who would want to spend thousands of dollars on equipment that they couldn’t use to make contacts with others that had also spent several thousands of dollars for equipment designed for the same purpose. Or so the theory went.

The unasked question became was another mode possible that would make completing an amateur radio contact (also known as a QSO) a slam dunk? As it turned out, someone was waiting in the wings, so to speak, to accomplish this.

A particular amateur radio operator whose call sign is K1JT who possessed seemingly impeccable credentials, decided on his own perhaps to fill the void to produce a mode of operation that was really easy to make contacts with. This mode was known as WSJT. As defined by its inventor the WS part meant Weak Signal and the JT part was the suffix of his call sign (K1JT). No modesty there at all.

The propagation modes this software was originally designed for was Meteor Scatter, Tropo Scatter and moon bounce. The stated intention of this software was to make these communications modes “easier” and more accessible to amateur radio operators that couldn’t afford large antenna arrays and expensive equipment. However the laws of physics begin to impinge here. It could be determined through mathematically based limitations that a certain level of technology was required to complete an eme contact. And no computer software could change that. Nevertheless Joe Taylor tried.

The WSJT program became so successful, some might say simple, that some of us that were almost lifelong amateur radio operators considered it too easy. And questions arose about the methods used by this code to communicate. I would complete Meteor Scatter contacts, for example, and when completed, I would comment that “this is too easy.”

One of these methods that made the JT software so easy was called “deep search” which is most applicable to the JT65 modes. This wasn’t a deep search of the cosmic microwave background radiation that was created at about the same time as the universe in the so-called “big bang” to detect a radio signal. Instead “deep search” was a elementary search of a database. This database consisted of amateur radio call signs and that is all that was searched for. It has been demonstrated by SM2CEW that if one tried to use WSJT to complete a moon bounce contact, if one of the participant call signs were not in the database supplied by the WSJT installation or if it were altered, there wouldn’t be a contact. The database is call3.txt.

To sum up what has been said to this point, communications off the moon was first accomplished by amateur radio operators in 1960. The mode utilized was CW. Single sideband contacts became feasible sometime later. As previously mentioned, to complete a contact, certain well defined information had to be sent and received by both operators attempting the contact. This required a certain bandwidth or data banwidth. The data bandwidth required to exchange this information was finite. Anything with lower bandwidth wouldn’t work. That is to say, exchanging the necessary data for a complete contact with a data bandwidth with less information, i.e. bandwidth, that the minimum bandwidth could provide was impossible. To say it differently, the WSJT bandwidth wasn’t adequate to complete a previously defined contact or QSO.

Unless one is educated in advanced mathematics and cryptology one generally lets the experts define the terms of the debate that establishes this concept.

These are links to the articles that question the legitimacy of the various forms of WSJT and its ever evolving forms:

A Comment on Joe's Paper „How Many Bits Are Copied in a JT65 Transmission?“

Communication using WSJT, JT65 ”Deep Search”

Deep Search Cannot Communicate Callsigns

I had an experience myself where the amateur radio station that wanted to work “my state” which is Oregon, became really upset when I didn’t apply the QSO criteria that are demystified in the articles cited above. The result is that he will never work Oregon on 432 MHz for the rest of his life. See, for example:

Communication via Moon Reflection by Radio and by Internet Part 1 by Barry Wright KA7V

This is a 3 part series but there are plentiful links to all parts in part 1.

To summarize for the benefit of those that dislike reading technical articles, there aren’t enough differentiated bits in the WSJT algorithm to allow the minimum transmission and reception of information required for an amateur radio contact to be completed. In other words WSJT is inadequate. Actually it is more than that, it is a fraud: it couldn’t be used to complete an amateur radio contact by exchanging the required data.

There is another paper that outlines the basis of modern communication theory which is extremely useful in this discussion.

A Mathematical Theory of Communication by C. E. Shannon

This article is way beyond the perceptible abilities of Joe Taylor to comprehend.

So sum it up one more time, Joe Taylor’s schemes are nothing more than propaganda, endorsed by the ARRL and other corporate lobbies, that are devoting enormous degrees of time and resources to convince those who lack the ability to make decisions for themselves that Joe Taylor’s algorithms are sufficiently robust to communicate radio messages between humans fulfilling the requirements for a contact. See above. I realize that my case is made and that I could stop here.

However if you search the internet for anything critical of Joe Taylor, K1JT, you will not find it. The level of propaganda supporting Joe Taylor is that profound. One has to look in scientific journals to find criticism of his methodology.

So this is Joe Taylor’s vision for amateur radio going forward. Not only does he want his concoction to be the only mode on VHF/UFH Meteor Scatter, Tropo Scatter and eme communications, he wants his software to become the dominate mode for high frequency communications as well. To accomplish this, he wants to rid the spectrum of other modes, like CW, and take control of frequencies these modes have historically used.

SM2CEW has reviewed what I have written and has suggested that the following points be added. I agree, so here they are:

1. It is essential and critical that each user of the popular WSJT protocols like JT65, FT8 (FTx) and Q65 protocols keep their PC clocks synchronized to the millisecond. Therefore everyone have to either be connected to an Internet time standard, or use their own Rubidium clock. If your PC is out of sync, you will not be able to decode messages. Traditional modes do not need this critical time sync and are therefore more reliable in every aspect of the word, especially during emergencies or when other resources are not available. 2. Not only is there a critical demand to be precisely synchronized in time, you also need to find out what protocol and what specific transmit/receive period length the other party is using plus which one is his transmit period. This his NOT something that the software will find out for you, you need to know this before hand to be successful. So to be successful you need another communication channel, parallel to the radio path to find this out. Or rely on some shady type of common consensus on how to operate which has proven to be very difficult, if not impossible 3. Random length text is not possible to convey over the radio, except for a very restricted 10-15 character message that will not be decoded unless signals are strong and the PC is exactly synchronized in time. In the case of an emergency, where amateur radio is often called upon, the ability to send any type of message has been the most important part of radio communications since radio was invented. As for ham radio, transmitting messages containing more than just two callsigns has always been the most important part of our hobby. Hence the earlier requirement at the exam to be able to copy CW messages 3-6 minutes long or more without any help of machines or computers. 4. Amateur radio in the form of WSJT totally rely on other resources like Internet access and computers just to be able to convey the most simplistic amount of data - two callsigns and a report. To see this as the future of amateur radio, just because one man is proud of his achievements, is nothing but a disgrace to everyone who uses traditional amateur radio to converse with other fellow radio amateurs. Or pass vital and important traffic when called upon for some reason. 5. There is also a big risk here as people anticipate that WSJT can be used successfully in an emergency situation. There will be a rude awakening for people who market the software as a robust and capable way of radio communication. Nothing could be further from the truth. Through the years amateur radio has over and over again proven itself to be the most important communication link during and immediately after disasters. Phone and CW operators have given us a strong reputation as a vital resource during such conditions. A WSJT operator is in NO way to be considered a resource during a disaster because his hands are tied, if he lacks the Internet he can't even convey his callsign and a report. And he can of course not send a highly important 300 character emergency message either.

The point that Peter is making is that WSJT/JT65 and other algorithms intended to replace CW are not conversational. All that is exchanged is a specific predetermined message that is very short in length and has to be synchronized in time by both participants. There is no conversational aspect to contacts when the K1JT methodology is used. And it is becoming so wide spread with no critical analysis that the effect it is having on amateur radio communication makes it impossible to tell your QSO partner what the weather is like or what equipment and antennas are used. Amateur radio communication has never been reduced to this and before K1JT’s propaganda assault was implemented, it would have been unthinkable.

If you want to send soundcard CW, and there can be reasons for doing that, there are programs like CwType that allow an exchange of information by Morse Code that is typed on a keyboard. CwType has memories and anything that can be typed on a keyboard can be sent. If one’s hand is injured, for example, and a person is unable to use an iambic keyer, CwType would be a good tool to use until one has recovered from an injury. Joe Taylor's propaganda campaign should be brought to the attention of the governmental agencies responsible for enforcing the American's with Disabilities Act.

What I am saying is that what you type is what is sent. The CW message is not predetermined in length and can be as long and creative as the sender wants. CwType can be download and easily installed. The site for downloading is DXSoft https://www.dxsoft.com/. There is an RTTY program there as well. All of these programs are quite different that anything created by Joe Taylor.

This video documents the Dutch Grand Prix Skating Race. The opening is one of the most stunning scenes on the planet. The ice, the sky, the snow, everything is incredibly beautiful. About 700 people from The Netherlands were in Sweden at the time of this recording competing in outdoor ice skating on the ice in Lulea Harbor Sweden to watch a Dutch Grand Prix skating race. The Dutch can not do so at home any more because of global warming. Their canals never freeze anymore. This is something that Joe Taylor could never appreciate. He lacks the ability to tell the difference between what is beautiful and what isn’t.

He doesn’t believe in sharing except for his own personal gain. He has ulterior motives for everything he does. He is less than human.

This is the kind of person the ARRL and other corporate lobbies are giving the future of amateur radio to.

You should remember that the current generation of CW operators may be the last. I got started when I was very young. I’m now 75. Nobody knows how much longer CW operation will last. However I can tell you that a CW exchange between two stations can be very brief. If you want the other operator’s name, you could simply send “name?” I’ve used examples of exchanges like this in contests that I have participated in. This amount of information could not be exchanged in such a short amount of time by any other mode.

In conclusion, if you don’t want a future without CW, time is running out for you to act.