Topic 40 JFET Operation and Biasing

This video presents the basic operating principles of the junction field effect transistor (JFET) and explains two common biasing techniques used with the JFET. Several example problems are worked out and a few similar homework problems are left as an exercise at the conclusion of the video.

[@AnalogDude_]

I have build clones of filters, Korg MS-20, Roland Jupiter 8 using BF256 and they sound awesome. Indeed a difficult component, but the simulators help lot. Thnx for the good video, i saved it for reviewing again later

[@Electronics4Guitar]

Thanks. Im a big fan of JFETs. I’m going to measure the Idss and Vgs(off) for a bunch of MPF102s in the next video and plot the average characteristics based on those numbers. I might do this with several different JFETs in a future video. Based on the BF256 specs, I suspect the data I compiled for the MPF102s would be nearly identical for the BF256.

[@AnalogDude_]

@@Electronics4Guitar Would you compare vs Mosfets? i got BF256 and MMBFJ202. aswel Rohm SH8MB5 and Advanced Linear devices ALD1105 (quad), the simulator says you can build a differential amp with these, but haven't send out the PCB yet.

[@AnalogDude_]

@@Electronics4Guitar Since we're talking about FET's, i have "designed" a automatic gain reduction in the simulator 2 days ago to protect a push pull amp exceeding the limits of the BD137/140, PSU, i wanna build, it uses FET's, it works, but did this without the math, would you like to help to make it accurate?

[@Electronics4Guitar]

@@AnalogDude_ I will be covering a bit of MOSFET stuff in a few weeks or so. The ALD1105 looks like an interesting device but I haven’t used them before. I’ve got a ton of side projects going and will be pretty busy for a while so I can’t promise I help you much with your design at this time. Keep me posted on your progress.

[@AnalogDude_]

@@Electronics4Guitar Well, i can make a video and make it only visible to you. Like i said, i have drawn up a synth modular differential amp. vca with current mirror in the sim, than i switched to mosfets in the simulator and the ALD1105 offers a quad package. it's expensive.

[@yiwi11]

would you like to make a video about analyzing AB class biased by Vbe multiplier

[@Electronics4Guitar]

@yiwi11 I plan on doing that sometime. I want to get through diff amps and more direct coupled circuits first. It may take a while but I’ll get there.