#jfet — Public Fediverse posts
Live and recent posts from across the Fediverse tagged #jfet, aggregated by home.social.
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Скромное очарование JFET
TL:DR Полевые транзисторы с управляющим p–n-переходом в большинстве — маломощные устройства, применяемые для усиления малых сигналов. Основное полезное свойство — огромное входное сопротивление и невысокий собственный шум (по сравнению с биполярными транзисторами). Мы разберёмся с основными свойствами этих транзисторов, рассмотрим схему усилительного каскада, сделаем усилитель и проведём простой опыт, демонстрирующий влияние электрического поля на ток через прибор. Уровень материала рассчитан на новичков.
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Electronics idea.
There are opamps with bipolar junction transistors (BJT) in the input stage.
There are others with junction field-effect transistors (JFET) in the input stage.
There are yet others with metal-oxide semiconductor field effect transistors (MOSFET) [1] in the input stage.
Idea: find an application for the bizarre possibility of an opamp with insulated-gate bipolar transistors (IGBT) in the input stage. This is more stunt-designing than anything practical.
[1] IIUC, "CMOS" opamps are really just MOSFET-input opamps. I'm not sure why the process technology name is more commonly used rather than the device type as is universally used for BJT and JFET input opamps.
#OpAmp #electronics #OperationalAmplifier #JFET #BJT #MOSFET #IGBT #CMOS #stunt
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Electronics idea.
There are opamps with bipolar junction transistors (BJT) in the input stage.
There are others with junction field-effect transistors (JFET) in the input stage.
There are yet others with metal-oxide semiconductor field effect transistors (MOSFET) [1] in the input stage.
Idea: find an application for the bizarre possibility of an opamp with insulated-gate bipolar transistors (IGBT) in the input stage. This is more stunt-designing than anything practical.
[1] IIUC, "CMOS" opamps are really just MOSFET-input opamps. I'm not sure why the process technology name is more commonly used rather than the device type as is universally used for BJT and JFET input opamps.
#OpAmp #electronics #OperationalAmplifier #JFET #BJT #MOSFET #IGBT #CMOS #stunt
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Electronics idea.
There are opamps with bipolar junction transistors (BJT) in the input stage.
There are others with junction field-effect transistors (JFET) in the input stage.
There are yet others with metal-oxide semiconductor field effect transistors (MOSFET) [1] in the input stage.
Idea: find an application for the bizarre possibility of an opamp with insulated-gate bipolar transistors (IGBT) in the input stage. This is more stunt-designing than anything practical.
[1] IIUC, "CMOS" opamps are really just MOSFET-input opamps. I'm not sure why the process technology name is more commonly used rather than the device type as is universally used for BJT and JFET input opamps.
#OpAmp #electronics #OperationalAmplifier #JFET #BJT #MOSFET #IGBT #CMOS #stunt
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Electronics idea.
There are opamps with bipolar junction transistors (BJT) in the input stage.
There are others with junction field-effect transistors (JFET) in the input stage.
There are yet others with metal-oxide semiconductor field effect transistors (MOSFET) [1] in the input stage.
Idea: find an application for the bizarre possibility of an opamp with insulated-gate bipolar transistors (IGBT) in the input stage. This is more stunt-designing than anything practical.
[1] IIUC, "CMOS" opamps are really just MOSFET-input opamps. I'm not sure why the process technology name is more commonly used rather than the device type as is universally used for BJT and JFET input opamps.
#OpAmp #electronics #OperationalAmplifier #JFET #BJT #MOSFET #IGBT #CMOS #stunt
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Electronics idea.
There are opamps with bipolar junction transistors (BJT) in the input stage.
There are others with junction field-effect transistors (JFET) in the input stage.
There are yet others with metal-oxide semiconductor field effect transistors (MOSFET) [1] in the input stage.
Idea: find an application for the bizarre possibility of an opamp with insulated-gate bipolar transistors (IGBT) in the input stage. This is more stunt-designing than anything practical.
[1] IIUC, "CMOS" opamps are really just MOSFET-input opamps. I'm not sure why the process technology name is more commonly used rather than the device type as is universally used for BJT and JFET input opamps.
#OpAmp #electronics #OperationalAmplifier #JFET #BJT #MOSFET #IGBT #CMOS #stunt
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Before I lost the job that I moved for, I had been planning to buy a decent LCD Oscilloscope, but that changed when I was let go.
Now I find myself needing an oscilloscope because I have to bias a bunch of JFET transistors.
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The opamps in the original are three dual-opamp NJM4558, which is a bog-standard dual-741 bipolar type. So pretty much any bipolar opamp should work just fine, I would think. I have 4558s - they're dirt cheap - so I used those, but I used sockets so I might try swapping them for something else and see if the sound changes at all. I might try #JFET ones like #TL07x .
The silicon clipping diodes in the original - in positions D3, D4, D5, D8, and D9 - are 1S2473 . I used #1N4148 instead.
There are also a pair of germanium diodes used for inline clipping (as opposed to more common signal-to-ground clipping). These are in positions D6 and D7. The original uses 1S188FM, and I substituted #1N60 .
The original circuit uses 5 different types of transistor, but one of those is only used in the soft-switching bypass route. So the only ones needed with my modified schematic are Q1, Q3, Q6, and Q7:
Q1 - original #2SK30A-Y N-channel JFET type. Unlike the rest, this one is still widely available, and I had some.
Q3 - original #2SC732TM-GR silicon NPN. I substituted #C945 / 2SC945.
Q6 - original #2SC2240-GR silicon NPN. I used #BC548 / SBC548.
Q7 - original #2SA970-GR silicon PNP. I used #BC558 / SBC558.
I used sockets for all the diodes and transistors, so I might try swapping some of those around too.
I might take some photos of the finished boards and add them tomorrow.
Hope someone found this interesting!
5/5
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In case anyone's keeping score, the idea that JFETs have hugely variable properties and that this problem cannot be - or at least has not been - fixed with different design or manufacturing practices, this batch showed it pretty clearly to me.
20 J113s, minus 1 fake, equals 19 devices. I measured the Vgs / pinch-off voltage and the Id / drain current in my test rig. The result?
6 very distinct bins with between 2 and 6 devices in each. Vgs overall varied from (-) 1.30 V to 2.11 V (variance is 38% of the larger value, or 62% of the smaller...), and Id from 5.7 mA to 12.8 mA, a spread of 125% (!) of the smaller value.
No wonder so many JFET circuits just don't work if you don't hand-match the devices.
#variance #variability #characteristics #measure #measurement #match #JFET #tolerance
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In case anyone's keeping score, the idea that JFETs have hugely variable properties and that this problem cannot be - or at least has not been - fixed with different design or manufacturing practices, this batch showed it pretty clearly to me.
20 J113s, minus 1 fake, equals 19 devices. I measured the Vgs / pinch-off voltage and the Id / drain current in my test rig. The result?
6 very distinct bins with between 2 and 6 devices in each. Vgs overall varied from (-) 1.30 V to 2.11 V (variance is 38% of the larger value, or 62% of the smaller...), and Id from 5.7 mA to 12.8 mA, a spread of 125% (!) of the smaller value.
No wonder so many JFET circuits just don't work if you don't hand-match the devices.
#variance #variability #characteristics #measure #measurement #match #JFET #tolerance
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In case anyone's keeping score, the idea that JFETs have hugely variable properties and that this problem cannot be - or at least has not been - fixed with different design or manufacturing practices, this batch showed it pretty clearly to me.
20 J113s, minus 1 fake, equals 19 devices. I measured the Vgs / pinch-off voltage and the Id / drain current in my test rig. The result?
6 very distinct bins with between 2 and 6 devices in each. Vgs overall varied from (-) 1.30 V to 2.11 V (variance is 38% of the larger value, or 62% of the smaller...), and Id from 5.7 mA to 12.8 mA, a spread of 125% (!) of the smaller value.
No wonder so many JFET circuits just don't work if you don't hand-match the devices.
#variance #variability #characteristics #measure #measurement #match #JFET #tolerance
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In case anyone's keeping score, the idea that JFETs have hugely variable properties and that this problem cannot be - or at least has not been - fixed with different design or manufacturing practices, this batch showed it pretty clearly to me.
20 J113s, minus 1 fake, equals 19 devices. I measured the Vgs / pinch-off voltage and the Id / drain current in my test rig. The result?
6 very distinct bins with between 2 and 6 devices in each. Vgs overall varied from (-) 1.30 V to 2.11 V (variance is 38% of the larger value, or 62% of the smaller...), and Id from 5.7 mA to 12.8 mA, a spread of 125% (!) of the smaller value.
No wonder so many JFET circuits just don't work if you don't hand-match the devices.
#variance #variability #characteristics #measure #measurement #match #JFET #tolerance
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In case anyone's keeping score, the idea that JFETs have hugely variable properties and that this problem cannot be - or at least has not been - fixed with different design or manufacturing practices, this batch showed it pretty clearly to me.
20 J113s, minus 1 fake, equals 19 devices. I measured the Vgs / pinch-off voltage and the Id / drain current in my test rig. The result?
6 very distinct bins with between 2 and 6 devices in each. Vgs overall varied from (-) 1.30 V to 2.11 V (variance is 38% of the larger value, or 62% of the smaller...), and Id from 5.7 mA to 12.8 mA, a spread of 125% (!) of the smaller value.
No wonder so many JFET circuits just don't work if you don't hand-match the devices.
#variance #variability #characteristics #measure #measurement #match #JFET #tolerance
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Measuring the characteristics of some cheap J113 / 2SJ113 n-channel JFETs I bought, so I can match them / divvy them into bins.
Put #15 of 20 into the JFET test circuit, and the power supply's current limiter kicks in ... whoops. Did I have it turned around so I swapped the terminals? Nope...
Take a peek at it. Slightly different marking. Still "J113", but the factory/date code is different. Put it in the component tester... it's a PNP BJT transistor, not a JFET at all, and with a pinout completely unsuitable for the JFET test circuit. If it had been in for more than a second, it probably would have let the Magic Smoke out.
Oh, #AliExpress sellers, where would #hobbyist #electronics people be without you? Somewhere with less excitement in their lives, I guess.
#MagicSmoke #Chinesium #fake #remarked #component #transistor #JFET #BJT #J113 #hobby
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Measuring the characteristics of some cheap J113 / 2SJ113 n-channel JFETs I bought, so I can match them / divvy them into bins.
Put #15 of 20 into the JFET test circuit, and the power supply's current limiter kicks in ... whoops. Did I have it turned around so I swapped the terminals? Nope...
Take a peek at it. Slightly different marking. Still "J113", but the factory/date code is different. Put it in the component tester... it's a PNP BJT transistor, not a JFET at all, and with a pinout completely unsuitable for the JFET test circuit. If it had been in for more than a second, it probably would have let the Magic Smoke out.
Oh, #AliExpress sellers, where would #hobbyist #electronics people be without you? Somewhere with less excitement in their lives, I guess.
#MagicSmoke #Chinesium #fake #remarked #component #transistor #JFET #BJT #J113 #hobby
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Measuring the characteristics of some cheap J113 / 2SJ113 n-channel JFETs I bought, so I can match them / divvy them into bins.
Put #15 of 20 into the JFET test circuit, and the power supply's current limiter kicks in ... whoops. Did I have it turned around so I swapped the terminals? Nope...
Take a peek at it. Slightly different marking. Still "J113", but the factory/date code is different. Put it in the component tester... it's a PNP BJT transistor, not a JFET at all, and with a pinout completely unsuitable for the JFET test circuit. If it had been in for more than a second, it probably would have let the Magic Smoke out.
Oh, #AliExpress sellers, where would #hobbyist #electronics people be without you? Somewhere with less excitement in their lives, I guess.
#MagicSmoke #Chinesium #fake #remarked #component #transistor #JFET #BJT #J113 #hobby
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Measuring the characteristics of some cheap J113 / 2SJ113 n-channel JFETs I bought, so I can match them / divvy them into bins.
Put #15 of 20 into the JFET test circuit, and the power supply's current limiter kicks in ... whoops. Did I have it turned around so I swapped the terminals? Nope...
Take a peek at it. Slightly different marking. Still "J113", but the factory/date code is different. Put it in the component tester... it's a PNP BJT transistor, not a JFET at all, and with a pinout completely unsuitable for the JFET test circuit. If it had been in for more than a second, it probably would have let the Magic Smoke out.
Oh, #AliExpress sellers, where would #hobbyist #electronics people be without you? Somewhere with less excitement in their lives, I guess.
#MagicSmoke #Chinesium #fake #remarked #component #transistor #JFET #BJT #J113 #hobby
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Measuring the characteristics of some cheap J113 / 2SJ113 n-channel JFETs I bought, so I can match them / divvy them into bins.
Put #15 of 20 into the JFET test circuit, and the power supply's current limiter kicks in ... whoops. Did I have it turned around so I swapped the terminals? Nope...
Take a peek at it. Slightly different marking. Still "J113", but the factory/date code is different. Put it in the component tester... it's a PNP BJT transistor, not a JFET at all, and with a pinout completely unsuitable for the JFET test circuit. If it had been in for more than a second, it probably would have let the Magic Smoke out.
Oh, #AliExpress sellers, where would #hobbyist #electronics people be without you? Somewhere with less excitement in their lives, I guess.
#MagicSmoke #Chinesium #fake #remarked #component #transistor #JFET #BJT #J113 #hobby
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JFET в роли регулируемого резистора
Привет, Хабр! Наверное, у многих словосочетание «регулируемый резистор» ассоциируется с обычным потенциометром. Потенциометр — это компромиссное решение, часто используемое на этапе отладки аналоговых узлов или в случаях, когда требуется аналоговое управление со стороны человека, например, для регулировки громкости в аудиоусилителе или изменения яркости света с помощью диммера.
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Homebrew Sferics Receiver Lets You Tune Into Earth Music https://hackaday.com/2024/10/30/homebrew-sferics-receiver-lets-you-tune-into-earth-music/ #RadioHacks #DawnChorus #earthmusic #whistlers #sferics #lm386 #jfet #vlf
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Homebrew Sferics Receiver Lets You Tune Into Earth Music https://hackaday.com/2024/10/30/homebrew-sferics-receiver-lets-you-tune-into-earth-music/ #RadioHacks #DawnChorus #earthmusic #whistlers #sferics #lm386 #jfet #vlf
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Homebrew Sferics Receiver Lets You Tune Into Earth Music https://hackaday.com/2024/10/30/homebrew-sferics-receiver-lets-you-tune-into-earth-music/ #RadioHacks #DawnChorus #earthmusic #whistlers #sferics #lm386 #jfet #vlf
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В погоне за звуком Билли Гиббонса. Часть 3: маленький секрет
Привет, Хабр! Мы продолжаем попытки повторить характер культовых ламповых стеков Marshall при помощи маленьких полупроводниковых гитарных педалей. Насколько это вообще возможно, и в чём состоит основная сложность? Впереди неожиданные открытия, проливающие свет на загадки гитарного звука.
https://habr.com/ru/companies/ruvds/articles/830942/
#ruvds_статьи #гитара #гитарные_эффекты #гитарные_примочки #гитарный_усилитель #гитаризм #электрогитара #электрогитары #музыкальные_инструменты #полевые_транзисторы #транзисторы #jfet
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This Open Source Active Probe Won’t Break the Bank https://hackaday.com/2024/06/13/this-open-source-active-probe-wont-break-the-bank/ #activeprobe #ToolHacks #BUF802 #buffer #op-amp #OPA140 #probe #jfet #RF
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This Open Source Active Probe Won’t Break the Bank - If you’re like us, the oscilloscope on your bench is nothing special. The lower en... - https://hackaday.com/2024/06/13/this-open-source-active-probe-wont-break-the-bank/ #activeprobe #toolhacks #buf802 #buffer #op-amp #opa140 #probe #jfet #rf
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В погоне за звуком Билли Гиббонса. Часть 2: JFET творят чудеса
Привет, Хабр! Сегодня я соберу ещё одну педаль для электрогитары, претендующую на характер звучания легендарного 100-ваттного стека Marshall Super Lead по прозвищу «Плекси» . Схема эффекта построена на четырёх полевых транзисторах с управляющим p-n переходом. Эти полупроводниковые приборы давно пользуются заслуженной любовью энтузиастов гитарного усиления и аналогового синтеза. Сегодня мы узнаем, почему
https://habr.com/ru/companies/ruvds/articles/817223/
#ruvds_статьи #гитара #гитарные_эффекты #гитарные_примочки #гитарный_усилитель #гитаризм #электрогитара #электрогитары #музыкальные_инструменты #операционные_усилители #полевые_транзисторы #транзисторы #jfet
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One for the JFET experts - I'm repairing a vectorscope which has a blown input FET on channel A.
This is the input circuit - A and B are the same, and the A and B input FETs (BF244Bs) are called out as "matched pair".
What parameter do I need to measure and match?
I figured Idss but that doesn't seem to have cut it, as the A- and B-ch have an offset error between them.
#electronics #ElectronicsRepair #JFET -
More #soldering done. All components are placed now, only have to do a few connections and jumper wires. I really notice how I'm improving.
Also, the return of the dancing #transistors, this time two #JFET.
#diysynth #perfboard #dancingtransistors -
Inside Electronic Gain Control - Normally, if you want to control the gain of an amplifier, you’ll use a variable r... - https://hackaday.com/2023/12/15/inside-electronic-gain-control/ #electronicgaincontrol #classichacks #op-amp #jfet
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JFET Stands in For Triode in This Infinite Impedance Detector - An “Infinite Impedance Detector” might sound a little like something that [Zaphod ... - https://hackaday.com/2023/02/10/jfet-stands-in-for-triode-in-this-infinite-impedance-detector/ #thermionicemission #demodulation #radiohacks #detector #triode #jfet #am #if #rf
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The new #deWalt interlocking #drillBit cases with clear covers are nice.
Whether these bits are any good on #styrene or #polycarbonate is another matter. The deWalt bits I had were no good (and one set I just got is likely identical to one I had, except for the case).
I don’t do much HW stuff, but sometimes am drilling into thing to house hokey little #electronics projects (such as my #JFET #opAmp continuity detector for making sure I didn’t screw up the connections in the next version).
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Practical Transistors: JFETs - Transistors come in different flavors. Tubes used an electric field to regulate cu... - https://hackaday.com/2022/06/02/practical-transistors-jfets/ #transistor #mischacks #mosfet #jfet