Recent content by MaxIokua

Right, thanks, I only have 2N2222A's, I will double check this.

Yes, it has a rubber bumper adhered to it so it is not shorting anything underneath.

So I finally received all the parts I was waiting for to finish a Chopshop V2. I am now having the same problem (ie no dirt), but worse! It is a clean boost but nothing more. I also can't get the JFET voltages above about 2.5 volts, even with the trimmers maxed. I have about 10 J201s and have...

Thanks @Robert, I had meant to get V2 but was sent V1 by Musikding. Many chop shop builds I scoured on the forum seem to be V1s so I didn't catch on at first when I was troubleshooting. Just wanted to add that I have swapped out Q1 for Vp -.865/Idss 588 and Q2 Vp .726/Idss 389 and, after...

I received the J201s I ordered much earlier than expected. Tested and selected Q1 as Vp=-.984V Idss=777uA and Q2 as Vp=-.865V Idss=588uA, trying to match Gray Bench's findings as closely as possible. Unfortunately this was not the magic bullet, although it did improve the anemia (lack of low...

Regardless, the drive doesn't sound like it should. To my ear the best (richest/fullest) sound I can get out of it is with Q1 and 2 at ~3.9V, but at this setting there is close to no clipping at max drive, and the sag control does almost nothing. If I adjust Q1 and 2 to the point where they will...

This really clarifies it. My uneducated guess is that my alleged J201s are behaving more like your J202 and 2n5457.

Thank you again, @temol - your diagram was much easier to comprehend....I'm now getting numbers that make more sense. 1.148 volts on Q1, 1.132 volts on Q2. Power supply was a 9v battery. So the Vp is a bit high for the purpose but not too crazy. I tried to test Idss by shorting G and S and...

I must be doing something wrong here. Following the breadboard layout from the link, I am getting ~6VDC Vp, and ~6mA Idss. Not .6, but full 6. I have double checked the procedure and measurements. I get similar results when using 1k/1 meg resistor method for testing Vp and Idss which I found...

I have ordered a few J201s and will let people know if it solves the no clipping issue. I also got a couple of 2N2222As just in case that is the culprit.

Great to know, thank you!

Interesting! That would explain a lot. Now to find real J201s...! I started a cursory search when the drive wasn't behaving as expected, it looks like they are hard to find. Is the MMBFJ201 considered comparable in this application?

Yes, all the way CCW. I have since set the trimmers by ear and would say the pedal is more or less working as it should, although it still has much less gain when maxed than I expected.

Thank you!

Thanks for the tip, but how do I measure Vp? And what numbers am I looking for to tell me whether these are J201s or not? Sorry for the noob question.