Transistor problems?

[insomniac2295]

So this isn't EXACTLY regarding a MadBean board, but it's close. I just did this Flexi Clip project from DIY-fever.com to my Glitterrattii and I'm having some problems with the transistors I'm using. I did a bit of googling around and found something from DIYstompboxes that describes my issue perfectly-

"Why does my pedal have a horrid crackling or "gating" sound when I play? I have to hit the strings really hard to get it to make sound and it's horrible.....

Answer: You have a classic case of a mis-biased transistor(s)."

I couldn't find much on diystompboxes about mis-biased transistors-at least I don't think I did. If I did, it was too over my head for me to understand. Can anyone help me out?

[madbean]

Do you mean the transistors in the clipping section? What have you used there? From his diagram on the website, if you are using 2n7000 you need to flip them opposite of how he has them drawn. The drain and gate pins should be tied together, not source and gate.

[insomniac2295]

Yeah, I'm talking about the transistors in the clipping section.

I just flipped the transistors around in their sockets so they look the opposite as drawn in his diagram. Is that correct? I'm still getting the same kind of fuzzy, flappyness as before.

[insomniac2295]

I'm also getting distortion when I have all the diodes and transistors on my DIP switch turned off. Is that something that should be expected? I know this isn't exactly your area of tech help seeing as it's not a madbean circuit, but I still appreciate the help!

[insomniac2295]

anybody?

[Scruffie]

Read through this - http://www.diystompboxes.com/smfforum/index.php?topic=29816.0

And post the information it asks for here, that'll give us something to go off.

[insomniac2295]

The rest of the circuit is fine. I did this flexi-clip add-on months after i built the original circuit. when i go through the 8 other diodes, everything's fine. the only problems i had was when i went to the MOSFETs. now, i took bean's advice and flipped around the 2n7000's so they matched the pinout of the bs170's used in the original plan for the flexi-clip. however, I'm still getting the same kind of gross, gated, buzzy sound out of the transistors.

here's a pic:

[insomniac2295]

please note, this picture was taken pre-transistor flipping

[jkokura]

Check this link out. http://www.muzique.com/lab/zenmos.htm

I think that your problem is you've tied the wrong legs of one of the transistors together. The drain of each transistor needs to be tied to the source, but in your example you've got the gate tied to the source on one side. They both need to be the same.

So for example, if you took that one jumper on the right mosfet and moved the jumper down one hole so it tied the lower pin of the transistor together with the middle pin of the transistor you'd have it right.

I don't know if that will for sure fix your problem. In fact, I don't know that's what the jumpers are doing for sure, but that's what I was guessing.

Jacob

[insomniac2295]

just realized i read the layout wrong and hooked up the drain on each transistor to the LED's right next to them. thanks for all the help! Sometimes you just need some people to help you talk it out