Replies to This Discussion

Permalink Reply by Servaas (Der Groovemeister) on April 5, 2011 at 12:13pm

You connected the input right. THe third wire from a stereo jack socket is for switching the 9 volt automaticly on when you insert the jack. Check all your solder connections: no shorts between different paths? Good connections? All used parts the right value? Orientation of the JFET transistor and the IC? A JFET transistor is very sensitive to static electricity and can be blown by touching it while you are not grounded. Did you use sockets for the JFET and the IC? Otherwise they can also be blown if you overheated them with the iron. Hope this helps and you get it working cause it's a great amp.

 

Permalink Reply by alectron on April 5, 2011 at 1:37pm

I had it set up on a breadboard, which is why I think it picked up the radio frequencies. The other thing I was wondering about was that I used the parts list on General Guitar Gadgets and when I looked at the schematic I noticed three capacitors have their values listed as N not UF, but capacitors I had where two 0.047 uf and .1 uf so I looked up cap values and didn't study it very well and just hooked 'em up. Do you think that might be the problem? I don't have the specified capacitors so I can't check.

Permalink Reply by John W on April 5, 2011 at 3:07pm

Do you have pics of your layout?

Double check all of your connections, especially the transistor ones.  Is the MPF102 connected properly?

Permalink Reply by erik brena on December 5, 2011 at 7:24pm

Not sure if you ever got your amp working? Ive built this circuit a few times and thought I would give my 2 cents.

The cap values you listed are correct. One problem Ive come across a lot with this circuit is unwanted distortion and a crazy squeal. I found that connecting a 220uf cap across pin 3 and 6 of the 386 fixes the problem. Not sure why it works, it just does.