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thephilosopheroftheboudoir · 6 years ago

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Grim History

Wallace D. Fard and the Secretive Origin Of the Nation of Islam

Much has been said, not so much actually known, about Wallace D. Fard. As the founding member of the Nation of Islam, his birth and death remain shrouded in mystery. Sources of information about his life are unreliable and after the start of the Black Muslim religious movement, Fard’s brief moment in the public eye receded as he seemingly disappeared into nowhere. One can only wonder how such an elusive individual could have started one of the most controversial religious organizations in American history.

Sources of Fard’s life leave much to the imagination and lack credibility for many. The largest file of biographical data comes from the FBI who opened an investigation into his life in the 1950’s when the Nation of Islam began to make waves. Federal investigators searched through legal records to track Fard’s movements but the inconsistency of Fard’s name and the conflicting accounts coming from people who knew him have made researchers suspicious. The FBI’s intent is also questionable as they may have been involved in a campaign of misinformation in an effort to discredit Wallace Fard for the sake of undermining the authority of the Nation of Islam itself. Another important source of knowledge about Fard comes from the sociologist Edmann Doane Beynon who published a sociological study of the NOI as they began to grow in Detroit during the 1930s. Beynon interviewed followers of Fard and published his research in a sociological journal. Handwritten letters from Wallace D. Fard to Elijah Mohammad have also been located. Most of the people who actually knew the man are dead.

The first written account of W.D. Fard came from Portland, Oregon on a birth certificate for his son. The mother, his common-law wife, described him as a dark-skinned man with brown eyes and wavy black hair who went by the name Wallie Dodd Fard. She claimed he had been born in New Zealand and made a living by running a food truck. Wallie Fard abandoned his family and later showed up in Los Angeles. Public records and a draft registration card for Word War I show that a Wallace D. Fard owned a restaurant. The draft registration form list his name as Wallace D. Fard but with “Ford” written under the name in quotation marks. His place of birth was listed as Afghanistan. A birth certificate also shows that this Ford was married and the father of a son. The next set of documents to surface were arrest forms and prison records, including fingerprints that match the draft registration, for a Wallace Dodd Ford, charged on counts of assault with a deadly weapon and transportation of bootleg liquor. This particular Ford did time in San Quentin where some say he met with Elijah Mohammad and the two of them schemed up a plan to charge people money for converting to Islam on their terms. This bit of information has been never been confirmed.

In the 1930s, a door to door salesman making was making his rounds in the African American neighborhoods of Detroit. Described as a light-skinned black man with an exotic accent, he became known to his customers as Wallace D. Fard Mohammad. He sold incense, perfume, candles, and colorful silks which he told the people had been imported from Africa. He claimed to be from Mecca and carried a copy of the Holy Bible with him so when potential customers invited him in to hear his sales pitch, he could ask them if they had been sufficiently versed in religion. Usually after making a sale, he would talk about God. More and more people grew interested in his message and soon they were holding secretive church meetings in their basements while W.D. Fard’s role as traveling salesman receded and his job as religious teacher became more important. Soon he stopped bringing his Bible and started bringing The Koran instead. Fard began telling his followers that the teachings of the Bible were wrong and the Christian church had been invented by the Caucasian white devils to enslave Black people. Thus, thrown into a state of spiritual crisis, psychological disorientation and confusion, Fard then enlightened them by explaining that African American people were the lost tribe of Shabazz who had been kidnapped by the Christian white devils and sold into bondage in America. He taught that The Koran was the true teaching of God and that Wallace D. Fard Mohammad was a messenger sent by Allah to take them back to their homeland.

Meanwhile, rumors began circulating in the African American community of Detroit that Fard’s “voodoo cult” was using his candles and incense to sacrifice babies to prepare his followers for the future murder of the white devils. This charge may or may not have been mere gossip.

One of the attendees at W.D. Fard’s meetings was Elijah Mohammad who claimed to be obsessed with Fard; a deep and close friendship developed between the two men. Elijah Mohammad said that Wallace Fard taught him everything he needed to know about Islam. The organization began to grow and he started to teach in highly regimented and disciplined groups who abstained from drugs, alcohol, pork and other unclean foods. The groups grew so big that they eventually rented a building which became know as the Mosque Number 1. About that time Wallace D. Fard Mohammad disappeared; Elijah Mohammad assumed the mantle of leadership and proclaimed the organization’s name to be the Nation of Islam.

Elijah Mohammad taught his followers that W.D. Fard was God incarnate. He laid out plans to form a separate state for African Americans that would eventually secede from the United States of American and form their own self-sufficient country. His message was one of Black empowerment, citing the necessity for African Americans to become economically independent of white society, who he routinely referred to as “blue eyed devils”. His teachings later attracted the attention of Malcolm X who would go on to become a prominent leader of the Civil Rights era. The Nation of Islam became a lightning rod for controversy and two newspaper articles were published in an attempt to weaken their influence over the African American community. One article claimed that W.D. Fard was a Turkish secret service agent who had worked for the Nazis; another article claimed that he was the son of a white man and a Polynesian woman who gave birth to him in Hawaii. These claimed have never been proven.

Elijah Mohammad, in his later years, embraced orthodox Sunni Islam. He toned down his rhetoric, stopped insisting on forming a separate, all-Black nation, and started preaching a message of peace for all humans. After his death, the American Islamic author Michael Mohammad Knight met with elder members of the Nation of Islam to ask about W.D. Fard. They told him he was ethnically Pakistani. He emigrated to America after being employed on an American cruise ship. When the Nation of Islam began to grow so big, he decided he did not want to live in the public spotlight and let Elijah Mohammad take over leadership of the movement, though he helped to run the sect behind the scenes. The two maintained a close friendship throughout their lives and spent many hours each day talking on the phone. W.D. Fard supposedly died circa 1980 and was buried in a grave with an assumed name, known only to the members of the Nation of Islam who knew him best.

Taking his name into consideration can lend some credibility to this story. The name “Wali”, short for “Walidad”, is of Arabic origin and is one of the most common names in Pakistan and Afghanistan. The name “Fard” is also a common Arabic name, sometimes spelled “Fahd”, “Fa’ad”, “Farad” or “Fahad” when written using Latin script. Those familiar with the transliteration of the Arabic script into English know that the phonetic sounds of Arabic, Urdu, and English do not match up , making multiple spellings of the same words a routine occurrence. Arabic has pure vowel sounds as opposed to English’s extensive use of glides, raisings, drops, and diphthongs in its vowels. Therefore, the capital of Oman can be variantly spelled “Moscat”, “Mouscat”, “Muscat”, or “Moskat” for example. Analysts of Fard’s handwriting have shown that he was a very poor speller and most often made mistakes in his use of English vowels. Samples of his signature written in Arabic script have also been analyzed and have shown that it contains idiosyncrasies that differentiate Urdu handwriting from Arabic, even though both languages use the same script.

So who was Wallie Dodd Ford and why all the confusion over the name? Some conspiracy theorists have said that he never existed; he was a fictional character made up by Elijah Mohammad so that he could claim to have received communications from Allah. Others say that Fard was from Venus and came to America in a UFO to spread the teachings of the Nation of Islam under God’s command. Invoking Occam’s razor can lead one to the more mundane conclusion that he was an ordinary man who emigrated to America but got off to a rough start. He could have been a con artist who changed his name to avoid being found by police, family members, or other nefarious individuals he had gotten associated with in his younger days. After all, this would not be the first time a religious movement had been started bya fraud. Maybe his message resonated with the right people and what he started grew too big so he decided to step aside and let someone else run the show. Possibly some narrow-minded authorities at the time could not comprehend the same Wali Fard and wrote his name as “Wallace Ford” on legal documents. Maybe he found solace and friendship in the African American community after facing too much racist adversity and xenophobia in the dominant white culture two decades before the dawn of the Civil Rights Movement and he turned his frustrations into a political theology.

Since most of the people who knew Wallace Fard are dead, we probably will never know the complete truth. In the end, if he was a con artist, would it really matter? Despite the extremely controversial nature of the Nation of Islam when it rose, that organization has also done some important things for the African American community. They were a key instigator in the Civil Rights Movement, they helped Black people establish successful businesses and careers, helped police Black neighborhoods, assisted criminals in re-adapting to life after reentry into society, and have had a high rate of success in helping people escape the nightmarish trap of drug and alcohol addiction. Maybe it is time to acknowledge that in some ways, a group of people should be judged according to their successes as well as their faults. If the two sides even out, can they be all that bad?

reference

Knight, Michael Muhammad. Blue Eyed Devil: A Road Odyssey Through Islamic America. Soft Skull Press, 2009.

https://grimhistory.blogspot.com/

#grim history #cults #wd fard #wallace d fard mohammad #nation of islam #american history

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cheat-codes-for-far-cry-vl8 · 2 years ago

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cheat codes for far cry vengeance

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ovnihoje · 4 years ago

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Objeto misterioso cai do céu para dentro do mar na Indonésia

Um objeto misterioso caiu nas águas da Indonésia, mas as autoridades do país não foram capazes de localizá-lo até agora ou formular uma teoria sobre o que teria sido. Ninguém conseguiu encontrar o misterioso objeto. Crédito: captrua de vídeo. O objeto parece cair a uma velocidade muito lenta até desaparecer na água. O autor do vídeo foi Asan Farades, um aluno de uma escola local, de onde…

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#Indonésia #objeto misterioso #ovni #ufo

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superdecade · 7 years ago

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Levidromes

A levidrome is a word that when spelled backwards makes another word. Well, at least not yet. It is not in the Oxford English Dictionary. Levi Budd is a six-year-old boy from British Columbia in Canada who has coined the term 'levidrome' after spotting that the word 'STOP' spells 'POTS' backwards. After realising that there is no such word in English for this phenomena, a social media campaign has started to get this word in popular usage (hence this post). I wrote a short Python script this morning that will pull all of the levidromes from a dictionary file. The full list is copied below.

youtube

aa ab aba abac abba abo abos abut acca ad ado ados ae aga agar agas agenes ah aha ahs aia aider air airts ajar aka al ala alan alif alma alula am ama amahs amas amen amene amir amis amla amman an ana anal anan anana anes anew anger animal animes anna annat anon ante apod araara arak arb arbas are ares arf aril arret arris arum arval aryl assam asses at ataata ate ates aua auks ava aval avel avid avo awa ay ayahs ba bac bacs bad bag bal bals ban bans bard barf bark bas bat bats bed beef ben bens bib bid big bin bins bird bis blub bo bob bobac bobak bod bog boh bok bon bonk boob boord bor bos bots bows boy bra braced brad brag braw bro brod bros bru bub bud bug bulb bun bunk buns bur burd burg bus but buts cab caba cabob cam camus cap card cares cep ceps cire cires cis cit cite cito civic clat cod cor cos cot cram cran crem cur da dab dace dad dag dah dahs dal dam dap daraf darb darg dart darts das daud daw daws day de deb debut decaf decal decarb dedal deed deem deen deens deep deeps deer dees deet deets def defer deffer deffo deg degami degged deid deified deifier deil deke deked del deled delf delis deliver delos dels deman demit demits den denier denies denim denis denned dennets dens depart deport depot depots derat derats dere dered deres deros derris dessert desserts deus devas devil devils devots dew dewans dewed dexes deys di dial dialer dials diaper dib did died dif dig dim din dinar diol diols diram dit div diva do dob doc dod dog doh dohs dol dom don dons doom door dop dopa dops dor dorb dormin dorp dorps dort dorter dos doser dot doy drab drac drail dram drap draps draw drawer draws dray drey drib drier droob drool drow drows drub duad dual dub dud duel duo dup dups ea ean eas eat ecad ecce ed edile edit ee eel eels een ef eh ehs eke eked elide elides elutes em eme emes emir emit emits emmets emong emos en ene enema enes enol enows er era ere ered eres ergo eric eros ervil eses esnes espial esse et eta etas etat etats eten etic etna euk eve even evil eviler evils ewe exul eye faced farad fe fed feeb feer fen fer fet fid fier fig fila fir fires fled flog flor flow fool fra frab fret fro gab gad gag gal gals gam gan gans gaps gar garb gas gat gateman gater gats gay ged gel gelder gem gen get gib gid gif gig gins gip girt girts git gnar gnat gnats gnaw gnaws gnome gnus gob god golf gon gons goog gorp gorps gos got grad gram grub gu gub gul gulp guls gum gums guns gup gups gur gut guv guy ha habus had hadedah hah hahs hajjah halalah hales hallah hallan halos han hap haram hay he heh henry hep her hey ho hob hod hoh hon hoo hoop hop hos huh hup id ikat imaged io iris iron is it itas iwi jar kabob kaiak kak kam kara kat kay kayak keek keel keels keep keet keets ken keps kier kips kirks kis kiths knaps knar knit knits knob knop knot knots know knub knuts kob kook kor korat kow krab krans kue la lab laced lacer lad laded laer lag lager laid laipse lair lam lamina lana langer lap lares larum las laud lava lavra leat leben led lee leek leep leeps leer lees leet leets leg leir lemel leper les let leud leva level lever levins levo lez liar liard liart lias lied lies lin lion lira lit live lived livre lobo lod loges loid lone loof looks loom loons loop loops loord loos loot looter loots lop los lotos lug luxe lyra ma mac macs mad madam maes mag mak mal malam mallam mals mam man map maps mar marah marc marcs mard marg marid marram marrum mart mas massa mat maws may me meed mees meet meets meg mem merc meter mets mew mho mid milks mils mim mined minim mips mir mis mm mo mod mom mon moo mood mool mools moops moor moos moot mop mor mos mot moy mu mug mum mura mural mures murram mus mut muton muts na naan nab nae nag nah nala nallah nam named namer nametag namma nan nana nap napas nappas naps naras narc narcs narks nas nat naw ne neb nebel ned nee need neep nef neg nek neks nelis nema nemas nep net nete nets neve neves new nib nid nil nimrod nip nips nis nit no nob nod nog noh noil nolos nom non nona nonet noo noon noop noops nori nos not notes notum now noy nu nub nun nur nus nut nuts nys oat ob oba obey obo obol od oda odas offed offer ogre oh ohm oho ohos oi oiks om on ono oo ooh oohs oom oon oop oor oot op oppo orb orf os otic otto oud ova ovel ow owt oxo oy pac pacer pad pah pal palp pals pam pan pans pap par pard part parts pas pat pats paw paws pay pec peed peek peel peels peen peep pees peh pelas pen peons pep per perp perts pets pig pin pins pip pir pis pit plap plug po pod poh pol pols pom ponk poo pooh pool pools poon poons poop poor poort poos poots pop port ports pos pot pots pow pows prat prep prod prog pud pug puh pullup pup pupils puris pus put puy radar rag raga rager rages raggas rail rait raj raja ram ramis rang ranid rank rap raps ras rast rat rats raw ray re real reaps rebus rebut recal recap recaps reccos redder redes redia redips redleg redraw redrawer reed reef reeks reel reels reens rees ref refed refer reffed reffo reflet reflow regal regar regna regnal regos reh reif reified reifier reik reiks reined reird reknit reknits reknot reknots relaid relit relive reliver reman remeet remit renies rennet rep repaid repaper repel repins repot repots res resat resod retag retem retool retrod retros revel reviled reviler reviver reward rewarder rewets rexes ria rial rias ribas riel rif rim rima rime rims rip rits rob roc rod rok rolf rom rones roo rood room rooms roop roops roots rosies rot rotator rotavator rotor rub ruc rucs rug rums run sab sabir sabra sad sadis sado sados sae sag saga sagas sagenes saggar sail sair sakis sal salep salles sallets sam sama samas samen san sanes sap sapan sappan saps sar saran saros sarus sat sate sati sav saved saw saz scab scam scares scot scram scran scur seals seam seat secret seder sedes sedile seed seeks seel seem seems seep seer sees segar segol seil seined seiner seis seisor seities sekos sel selah selahs seles sellas selles seme sememes semes semina sena senas sene senega senegas sennet senor sense ser sera serac seracs seral sere sered seres seric serif serons serres serum sese sesey sessa sesses set seta seton setule seven sexed sexer sexes sey seys sha shad shah shahs shakos shales shama shay shaya she shod shoo shtik si sib sic sidas sies sik sikas siled silen sim sima simar simis sin sined sinnet sip siri siris sirra sirred sirs sirup sis sit six skat skeer skees skeets sken skeps skier skio skips sklim skool skran skrans skrik skua slab slaes slag slaid slam slap sled slee sleek sleep sleeps sleer sleet sleets slim slipup slit slive slived sloid sloom sloop sloops sloot sloots slop slug smart smees smew smir smits smoor smoot smug smur smut smuts snab snag snap snaps snark snarks snaw snawed snaws sneb sned sneed sneer snib snig snip sniper snips snirt snit snivel snod snoep snog snool snoop snoops snoot snores snort snot snow snub snug so sob soba soc soccer sod soda sodas sog soger soh soho sokahs sokes sol solah soled solon solos som some son sonnet sool soom soop sop soras sorb sore sored sorter sos sotol sow soy spacer spaer spag spam span spank spans spar spard spart sparts spas spat spats spaw spaws spay spaz spec speed speel speels spek speks spets spider spik spiks spim spin spins spirt spirts spit spod spool spools spoom spoon spoons spoor spoots sports spot spots sprat sprits sprod sprog spud spug sris stab stag stang stap staps star stared start stat state stats staw staws steed steek steeks steel steels steem stellas stem stemme sten stenned step steps stet stets stew stewer stime stimed stims stink stinker stir stirps stob stonk stonker stool stools stoop stoops stoor stop stoped stoper stops stot stots stoved stow stows strad strap straps straw strep stressed stria strig strips strop strops strow struts stub stum stums stun stunk sturts sub subah suber succus sued sulu sulus sum sumac sun sung sup suras sus susus swad swam swang swans swap swaps sward swat swats sway swey swob swone swop sword swot swots syed syes syn ta tab tae tael taes tag tak taki taks talc tallat tam tan tang tanna tao tap taps tar tared tarok tarp tarps tart tas taser tat tate tats tav taw taws te teed teek teel teels teem teemer tef teg tel telfer ten tenet tenner tennes tennis tennos tenon terces terf terra terret tes tet tets tew ti tiar tic tid tide tig til tiler tils time timed timer tin tink tinker tins tip tips tirrit tis tit toc tocs tod tog tom ton tonk tonker tons too tool tools toom tooms toons toot top toped toper tops tor torot tort tot tots tow tows trad trail tram trams trap traped traps trat trats tressed trew trig trins trips trod trons troop trop troped trot trow tsar tub tuba tubed tuber tug tum tums tun tup tut two ug ulu ulus um umu un urb utu vas vat vav vid vug wad wan wang wans wap waps war warb ward warder warts was wat wats waw way wed wem wems wen wena wert wet wets wey wo wok wolf wolfer won wonk wons wop word wort worts wos wot wots wow xis ya yad yag yah yahs yak yam yap yaps yar yard yaw yaws yay yebo yeh yerd yes yeses yew yews yo yob yod yom yon yos yrneh yug yup zaps zas zel ziz zuz zzz

It is interesting to note that some levidromes are also palindromes. I wonder whether we need a new word to describe this phenomenon also? Furthermore, there is no word in English for "a word that you make up in order to make another word make sense". I suggest: "emordivel" ?

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jaimeariansencespedes · 5 years ago

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067 – FARADAY: INDUCCIÓN (1831), GENERADOR (1831-1832), LEYES Y JAULA DE FARADAY.

El físico y químico inglés Michael Faraday (1791-1867), discípulo de Humphrey Davy, es conocido principalmente por su descubrimiento de la inducción electromagnética, que ha permitido la construcción de generadores y motores eléctricos, y de las leyes de la electrólisis por lo que es considerado como el verdadero fundador del electromagnetismo y de la electroquímica. En 1831 trazó el campo magnético alrededor de un conductor por el que circula una corriente eléctrica, ya descubierto por Oersted, y ese mismo año descubrió la inducción electromagnética, demostró la inducción de una corriente eléctrica por otra, e introdujo el concepto de líneas de fuerza para representar los campos magnéticos.

Durante este mismo periodo, investigó sobre la electrólisis y descubrió las dos leyes fundamentales que llevan su nombre:

1. La masa de sustancia liberada en una electrólisis es directamente proporcional a la cantidad de electricidad que ha pasado a través del electrólito [masa = equivalente electroquímico, por la intensidad y por el tiempo (m = c I t)];

2. Las masas de distintas sustancias liberadas por la misma cantidad de electricidad son directamente proporcionales a sus pesos equivalentes.

Con sus investigaciones se dio un paso fundamental en el desarrollo de la electricidad al establecer que el magnetismo produce electricidad a través del movimiento.

En su honor se denominó Farad (símbolo F), castellanizado como Faradio, a la unidad de capacidad del SI de unidades. El Faradio se define como la capacidad de un condensador tal que cuando su carga es un Culombio, adquiere una diferencia de potencial electrostático de un voltio.

A pesar de la escasa educación formal recibida, Faraday es uno de los científicos más influyentes de la historia. Mediante su estudio del campo magnético alrededor de un conductor por el que circula corriente continua, fijó las bases para el desarrollo del concepto de campo electromagnético.

También estableció que el magnetismo podía afectar a los rayos de luz y que había una relación subyacente entre ambos fenómenos.

Descubrió asimismo el principio de inducción electromagnética, el diamagnetismo, las leyes de la electrólisis e inventó algo que él llamó dispositivos de rotación electromagnética, que fueron los precursores del actual motor eléctrico.

En el campo de la química, Faraday descubrió el benceno, investigó el clatrato de cloro, inventó un antecesor del mechero de Bunsen, el sistema de números de oxidación e introdujo términos como ánodo, cátodo, ion, electrodo. Finalmente, fue el primero en recibir el título de Fullerian Professor of Chemistry en la Royal Institution de Gran Bretaña, que ostentaría hasta su muerte.

Faraday fue un excelente experimentador, que transmitió sus ideas en un lenguaje claro y simple. Sus habilidades matemáticas, sin embargo, no abarcaban más allá de la trigonometría y el álgebra básica. James Clerk Maxwell tomó el trabajo de Faraday y otros y lo resumió en un grupo de ecuaciones que representan las actuales teorías del fenómeno electromagnético.

El uso de líneas de fuerza por parte de Faraday llevó a Maxwell a escribir que "demuestran que Faraday ha sido en realidad un gran matemático. Del cual los matemáticos del futuro derivarán valiosos y prolíficos métodos".

Historia de la Ciencia – [email protected]

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apogeewebelectronicblog · 6 years ago

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Any idea about what Electrolytic Capacitor is? Come on in.

1.The Basic Knowledge Of Electrolytic Capacitors

1.1 Definition

Electrolytic capacitor is a kind of capacitor divided by structure and manufacturing technology. In general, electrolytic capacitors are of polarized capacitors. The anodes of electrolytic capacitors adopt metal materials that can be passivated, such as aluminum, tantalum, niobium, titanium, etc. The dielectric material is a dense oxide film formed on the surface of anode metal material. The cathodes of electrolytic capacitors adopt electrolytes.The main feature of electrolytic capacitors is that they are possible to obtain a much larger capacitance than ordinary capacitors(assuming equal withstand voltages). Electrolytic capacitors get their name from the fact that they use electrolytes as cathodes.

This video explains what is electrolytic capacitor

1.2 Parameters

— Rated capacitance

Rated capacitance is the capacitance marked on the capacitor.

— Basic unit

The basic unit of a capacitor is farad (F), but this unit is too large to be used in actual situation.

The relationship among other units are as below:

1F=1000mF

1mF=1000μF

1μF=1000nF

1nF=1000pF

—Accuracy

The deviation between the actual capacitance and the rated capacitance is called an error, and the accuracy is an error that is within the allowable deviation range.

The corresponding relationship between the accuracy level and the allowable deviation is: 00(01)-±1%、0(02)-±2%、Ⅰ-±5%、Ⅱ-±10%、Ⅲ-±20%、Ⅳ-(+20%-10%)、Ⅴ-(+50%-20%)、Ⅵ-(+50%-30%)

Ordinary capacitors are often of the Ⅰ, Ⅱ, Ⅲ level, while electrolytic capacitors are often of the Ⅳ, Ⅴ, Ⅵ level.

—Nominal voltage

Nominal voltage is the maximum effective value of DC voltage that can be continuously applied to capacitors under the lowest ambient temperature and the rated ambient temperature. Generally, it is directly marked on the capacitor case. If the working voltage exceeds the withstand voltage of the capacitors, they will break down and irreparable permanent damage will be caused.

—Insulation resistance

A DC voltage is applied to capacitors and a leakage current is generated. The ratio of the DC voltage and leakage current is insulation resistance.

When the capacitance is small, insulation resistance mainly depends on the surface state of the capacitor. When the capacity >0.1uf, it mainly depends on the performance of the medium. The larger the insulation resistance is, the better.

—Time constant

Time constant is introduced to evaluate the insulation of large capacitor. It is equal to the result of insulation resistance multiplying capacitance.

—Loss

Under the action of electric field, the energy consumed by capacitors due to heat in unit time is called loss. All kinds of capacitors stipulate their own allowable loss value within a certain frequency range. The loss of capacitors is mainly caused by dielectrics, conductance loss and resistance of all metal parts of capacitors.

Under the action of direct current electric field, the loss of capacitors exists in the form of leakage conduction loss, which is generally small. Under the action of alternating electric field, the loss of capacitors is related not only to leakage conduction, but also to the periodic polarization establishment process.

—Frequency

With the increase of frequency, generally the capacitance of capacitors decreases.

—Polarity and circuit notation

—Equivalent circuit

leakage: Electric leakage resistance

ESR: Equivalent Series Resistance

ESL: Equivalent Series Inductance

1.3 Lifespan of electrolytic capacitors

Life expectancy: The duration of continuous operation of the electrolytic capacitor at the highest operating temperature.

lx=lo*2(to-ta)/10

lx=actual working life

lo=warranty life

to=maximum working temperature

ta=the actual working temperature of the capacitor

2.The Classification Of Electrolytic Capacitors

Electrolytic capacitors are generally divided into three categories: aluminum electrolytic capacitors, tantalum electrolytic capacitors and niobium electrolytic capacitors.

2.1Aluminum electrolytic capacitors

2.1.1 Introductions

Aluminum electrolytic capacitors are polarized electrolytic capacitors. Their anodes are made by aluminum foil with an etching on the surface. The aluminum foil is coated with a thin layer of alumina insulating layer, which is the dielectric of capacitors. The alumina is coated with a non-solid electrolyte, which is the cathode (-) of capacitors. There is another layer of aluminum foil, known as "cathode aluminum foil”, which contacts the electrolyte and is connected to the negative terminal of capacitors.

Aluminum electrolytic capacitors can be divided into three types according to the types of their electrolytes: non-solid aluminum electrolytic capacitors; solid aluminum capacitors whose electrolyte is solid manganese dioxide; polymer capacitors whose electrolytes are solid polymers.

Non-solid aluminum electrolytic capacitors are the cheapest kind and have the widest range of sizes, capacitance and voltage levels. Their minimum capacitance is 0.1µF and the maximum is 2.7 million µF (2.7 F), with voltage ranging from 4 V to 630 V. Liquid electrolytes provide the required oxygen as the dielectric oxide layers recovers themselves. But electrolytes will evaporate and the drying process varies with temperature, causing electrical parameters to drift and limiting the capacitor's life.

structure of aluminium electrolytic capacitors

2.1.2 Advantages And Disadvantages

Advantages

—Aluminum electrolytic capacitors are cheap with high capacitance and can be used in wave filtering at lower frequencies.

—Their energy density is higher than that of thin-film capacitors and ceramic capacitor.s

—Their power density is higher than that of double layer capacitors.

—There is no limit posed by peak current.

—There are many variations in appearances and styles, as well as customized life, service temperature and electrical parameters.

—There are many manufacturers for aluminum electrolytic capacitors.

Disadvantages

—The life of the aluminum electrolytic capacitors is limited by the evaporation of electrolytes.

—Aluminum electrolytic capacitors are sensitive to mechanical stress.

—Aluminum electrolytic capacitors are sensitive to halide pollution.

2.1.3 Application

Aluminum electrolytic capacitors are usually used in power supply of a lot of electrical equipment, switch mode power supplies and DC-DC converters. They are also used in many industrial power converters and frequency converters. Some special capacitors are used for energy storage, such as strobe lights, flash strobes, or frequency coupling devices used in audio.

Aluminum electrolytic capacitors are polarized capacitors due to their anodic oxidation. They can only be used togetherwith the correct polarity of direct current. If they are connected to the opposite polarity of direct current or an alternating current, they will be destroyed out of short circuit. The only exception are bipolar aluminum electrolytic capacitors, which can be used in alternating current.

2.2 Tantalum electrolytic capacitor

2.2.1 Introduction

Tantalum electrolytic capacitors’ anodes are made by tantalum particles, covered by insulation oxides as dielectrics, surrounded by liquid or solid electrolytes acting as cathodes. Because tantalum electrolytic capacitors have thin dielectric layers and high capacitivity, their capacitance per unit volume is larger than that of ordinary capacitors and other electrolytic capacitors.

structure of tantalum electrolytic capacitors

At present, tantalum electrolytic capacitors are mainly divided by three types: sintered solid, foil-shaped winding solid and sintered liquid, among which the sintered solid accounts for more than 95% of the total production, and the major kind is the non-metallic sealed resin package.

The working medium of tantalum electrolytic capacitors is an extremely thin tantalum pentoxide film formed on the surface of tantalum. This layer of oxide film medium is integrated with one end of the capacitor and cannot exist alone. Therefore, the capacitance per unit volume is particularly large. That is, the specific capacity is very high, so it is particularly suitable for miniaturization.

In the work process of tantalum electrolytic capacitors, they have the capacity of automatically repairing or isolatingdefective properties in the oxide film, so that the oxide film medium can be strengthened and recover its due insulation ability at any time without suffering continuous cumulative damage. This unique self-healing ability guarantees theiradvantages of long life expectancy and reliability. The capacitors have unidirectional conductivity, that is, they have"polarity". In application, the current should be connected according to the positive and negative direction of the power supply. The anodes of the capacitors are to be connected to the "+" pole of the power supply, while the cathodes are to be connected to the "-" pole of the power supply. If the capacitors are misconnected, not only they wouldn’t work but also the leakage current would be huge. As a result, the core will heat up in a short time, damaging the oxide film and then depriving it of efficacy.

2.2.2 Advantages And Disadvantages

Advantages

—Small in size

Since tantalum electrolytic capacitors are made of tantalum powder, and the dielectric constant of tantalum oxide film is 17 higher than that of aluminum oxide film, the capacitance of tantalum capacitors per unit volume is larger.

Wide operating temperature range

Generally, tantalum electrolytic capacitors can work normally at the temperature of -50℃~100℃. Although aluminum electrolytic capacitors can also work within this temperature range, their performance is far inferior to that of tantalum electrolytic capacitors.

—Performance

The tantalum oxide film medium in tantalum electrolytic capacitors is not only corrosion resistant, but also has long service life, high insulation resistance, low leakage current and good performance for a long time.

—Impedance frequency

The solid electrolytic capacitors can work in the frequency of above 50kHz. The capacitance of tantalum electrolytic capacitors decreases with the increase of frequency, but the decrease degree is small. Data show that the capacitance of tantalum electrolytic capacitors decreases by less than 20% when operating at 10kHz, while the capacitance of aluminum electrolytic capacitors decreases by 40%.

—High reliability

The chemical properties of tantalum oxide film are stable. Since Ta2O5, the substrate of tantalum anode can withstand strong acid and alkali, tantalum electrolytic capacitors can use solid electrolytes or liquid electrolytes with very low resistivity containing acid. As a result, the loss of tantalum electrolytic capacitor is smaller than that of aluminum electrolytic capacitors.

Disadvantages

Tantalum electrolytic capacitors are expensive and have limited capacitance compared with other types of capacitors due to their not using electrolytes as medium.

2.2.3 Application

Tantalum electrolytic capacitors have various shapes and are easily fabricated into small components suitable for surface mount, which meets the needs of automation and miniaturization of electronic technology. Although tantalum is scarce and tantalum electrolytic capacitors are relatively expensive, due to the large adoption of high specific capacity tantalum powder (30kuF.g-100kuF. V/g) and the improvement and perfection of capacitor manufacturing technology, tantalum electrolytic capacitors have been rapidly developed and used in an increasingly wide range. Tantalum electrolytic capacitors are widely used not only in military communication, aerospace, but also in industrial control, film and television equipment, communication instruments and other products. In addition, because tantalum electrolytic capacitors are capable of storing electric quantity, charging and discharging, etc, they are also used in filtering, energy storage and conversion, mark bypass, coupling and decoupling, and used as time constant element.

2.3 Niobium electrolytic capacitor

2.3.1 Introduction

Niobium electrolytic capacitors are polarized capacitors. Their anodes (+) are passivated niobium or niobium oxide with insulating niobium pentoxide as the dielectrics of niobium capacitors. On the surface of the oxide layer is a layer of solid electrolyte, which is the cathode (-) of niobium electrolytic capacitors.

structure of niobium electrolytic capacitors

Back in the 1960s, headed by the United States and the Soviet union, many countries began the study of niobium electrolytic capacitors. But in the studying process, niobium pentoxide dielectric film suffered severe damage due to heat and electrical stress, resulting in large leakage current in capacitors and high failure rate. Since the 1990s, with the constant improvement in powder production technology, the electric properties of niobium powder had improved a lot, laying a solid foundation for the development of niobium electrolytic capacitors. The new type of niobium electrolytic capacitors are of good performance and low price, which have attracted wide attention from all over the world. The preparation of niobium electrolytic capacitors must meet the requirements below: 1.Avoid the oxygen supersaturation in niobium anode, that is, the formation of suboxide must be prevented; 2. Inhibit oxygen migrating through Nb2O5 membrane and Nb/Nb2O5 interface; 3. Ensure the thermal stability of dielectric layer. British company AVX has supplied niobium electrolytic capacitor samples, whose capacitance range is 100-470µF and working temperature is up to 105℃. Companies like Kemet in US and NEC in Japan--the world's leading enterprises in tantalum electrolytic capacitors are working actively to develop niobium electrolytic capacitors. Russia is also of the high level in this area due to its continuous research on the basis of the studies of the former Soviet Union.

In addition, there are tantalum-niobium alloy electrolytic capacitors, whose anodes are formed by the sintering of tantalum-niobium alloy powder. And the medium is an oxide film that is chemically formed on the surface of the positive electrode. The performance of such electrolytic capacitors is second only to that of tantalum electrolytic capacitors and superior to that of aluminum electrolytic capacitors. Because niobium is abundant and the price is moderate, this kind of alloy capacitors have a promising future.

2.3.2 Advantages And Disadvantages

Advantages

—With the same capacitance, the dielectric constant of niobium electrolytic capacitors is twice as large as that of the tantalum electrolytic capacitors.

—The chemical stability of niobium electrolytic capacitors is better than that of aluminum electrolytic capacitors.

—Leakage current and loss are small.

Disadvantages:

Niobium electrolytic capacitors can also form dielectric oxide film on their surface. The biggest problem of niobium electrolytic capacitors is the damage to dielectric oxide film caused by heat and electrical stress will lead to the increase of leakage current and the failure of capacitor.

2.3.3 Application

Niobium electrolytic capacitors have entered the high specific capacity capacitor market, and they have a capacity/voltage range similar to ordinary tantalum electrolytic capacitors and equivalent series resistance characteristics similar to standard tantalum electrolytic capacitors. Niobium electrolytic capacitors are low in price and stable in performance, which can replace some tantalum electrolytic capacitors, ceramic capacitors and aluminum capacitors. Niobium capacitors are not prone to break down due to ignition, which guarantees the safety of the circuit. The high leakage current of niobium electrolytic capacitors is not a problem for most applications because the maximum residual current is well below 50μA. For example, in the use of personal computers (PCS), this number is rather small compared to the total power consumption of the microprocessor and does not make much difference. The life test proves that the capacitance of niobium electrolytic capacitors is stable, and the leakage current increases continuously with time, but the growth rate decreases and the saturation state appears, which is caused by the instability of niobium anodized film. Niobium electrolytic capacitors are modified to avoid the formation of suboxide and to stabilize dielectric oxide film. With the development of electronic circuit and electronic industry, niobium electrolytic capacitors are to be introduced into the market as a new type of capacitor and open up its application field.

3.Characteristics Of Electrolytic Capacitors

—The capacitance per unit volume of electrolytic capacitors is very large, which is tens to hundreds of times larger than that of other kinds of capacitors.

—Rated capacitance can be very large, easily reaching tens of thousands of μf or even several f.

—The price of electrolytic capacitors is overwhelming superior to other kinds because electrolytic capacitors are made of ordinary industrial materials, such as aluminum. The equipment used to make electrolytic capacitors is common one, which can be mass produced with relatively low cost.

4. Notes For The Use Of Electrolytic Capacitors

—The actual voltage of the electrolytic capacitors in the circuit should not exceed their withstand voltage value. When using electrolytic capacitors, be noted that the positive and negative poles should not be reversedly connected. In the power circuit, when the positive voltage is to be output, the anode of the electrolytic capacitor is to be connected to the output end of the power supply, while the cathode is to be connected to the ground. When the output voltage is negative, the cathode is to be connected to the output end and the anode is to be connected to the ground. Different types of capacitors should be used for different circuits. Before loading capacitors into the circuit, make sure that there are no situations like short circuit, open circuit and electric leakage, and the capacitance value should be checked. When installing, make it easy to see the type of capacitor, capacity, withstand voltage and other symbols for verification.

—When the polarities of the filter capacitor are reversedly connectd in the power supply circuit, the filtering effect of the capacitor is greatly reduced. On the one hand, the output voltage fluctuation of the power supply is caused, and on the other, the electrolytic capacitor which is equivalent to a resistor is heated by reverse current. When the reverse voltage exceeds a certain value, the reverse leakage resistance of the capacitor becomes very small, which will cause the capacitor to burst and to be damaged due to overheating soon after being energized.

—The voltages applied to both ends of the electrolytic capacitors must not exceed its permissible working voltage. In the design of the actual circuit, there should be permissible range of the voltage according to specific situation. In designinga filter capacitance of regulated power supply, if the AC power voltage is 220V, the subordinate commutating voltage of transformer can be up to 22V, a electrolytic capacitor with withstand voltage that is 25V in drawing a design for PCB can generally meet the requirements. However, if the AC power supply voltage fluctuates greatly and may rise to more than 250V, it is better to choose a electrolytic capacitor that can withstand more than 30V.

—Electrolytic capacitors should not be near the high-power heating element in the circuit to prevent the electrolyte from drying up rapidly due to heat.

—For filter with positive and negative polarity, two electrolytic capacitor could be connected in series with the same polarities and make a nonpolarized capacitor.

—The capacitor case, auxiliary lead terminals must be completely isolated with positive and negative poles and circuit boards.

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