Help with my first pedal build. (Flipster)

mjwhit · #1 03-22-2009, 06:52 PM

This is my first build. I have done a bit of stuff before, guitar electronics etc but nothing like this.

Working on a flipster from runoffgroove.com.... but when i plug it in i just get a bit of noise(reasonably quiet), no guitar input, but for some reason when i touch the strings on my bass the noise will change.

EDIT=after some tinkering, I have very low output.
Is it possible i put a wrong value capacitor somewere and its blocking these frequencies?

Ive double checked my layout and soldering, but now i dont know what to check now.

Could you guys give me some hints please?

Once i get it going i will add a bypass and an led, but one thing at a time.

Thanks in advance

and itl be going in here once its going

rcubed · #2 03-22-2009, 07:04 PM

Wow, a trimpot for every transistor. Double check to make sure you have the proper orientation of the transistors. The gate, source and drain might be different. Check for solder bridges that might be shorting something out.

mjwhit · #3 03-22-2009, 07:56 PM

theyre facing the right way. i havnt used sockets for them though. any chance i may have fried one when i soldered them in?

katri · #4 03-23-2009, 01:43 AM

Possibly. I've fried a few transistors when soldering at college.

rcubed · #5 03-23-2009, 07:27 AM

Have you measured the voltage at the collector, making sure it's ~4.5V?

rratajski · #6 03-23-2009, 08:15 AM

Just for kicks, check the value of the resistors. Once, I had a big muff issue where I was letting too much signal go to ground b/c I threw a smaller resistor than I should've had in there...It sounds similar to your issue...

mjwhit · #7 03-25-2009, 03:37 PM

So i replaced all the transistors. And had a general resolder of almost everthing. Im definatly better off, but still not working properly.

I think its a short somewere.... im going to havto go over my diagram again.

I now have signal out at good volume but gain, bass and treble controls dont work. Wierd. Also only the final trimpot seems to be doing what its ment to.

so i reckon the short must be early on bypassing almost the entire circuit....

Quote:

Have you measured the voltage at the collector, making sure it's ~4.5V?

Its about 9v, but i dont think i can change it until i can find this short and get the trimpots going again

Thanks for the help

vin*tone · #8 03-25-2009, 06:23 PM

have you tried tracing the signal with an audio probe?
http://www.diystompboxes.com/pedals/debug.html
The signal will drop out somewhere in the circuit - this will tell you exactly where.

mjwhit · #9 03-25-2009, 07:16 PM

Quote:

have you tried tracing the signal with an audio probe?
http://www.diystompboxes.com/pedals/debug.html
The signal will drop out somewhere in the circuit - this will tell you exactly where

Ive been doin the audio probe. ive been on a mission all day trying to find were the problem is. Some funny business is definatly going on...

mjwhit · #10 03-25-2009, 10:14 PM

O.K guys we are almost there. After biasing the FET's to 4-5 volts and introducing a 9v adapter into the mix, we have output that is a little disapointing.

It doesnt break up at all, even at full gain im getting a clean signal. What??

And even at full gain and full volume, the output is fairly significantly quieter than the input.

Im thinking the reason is that I used MPF106's because that was all that the local shop had in stock. Should i look for something else or is it another problem?

Thanks

rcubed · #11 03-25-2009, 10:34 PM

I just noticed that you're working FETs.

Never mind that emitter voltage talk. Biasing the transistors to that range is a good idea but since you're using a different type, results may vary. So adjust the trimpots until you like what you hear (assuming you have no other errors in the circuit wiring).

If you think you'll be building more circuits in the future, it's always good to prototype the circuit on a bread board. That takes soldering out of the troubleshooting equation.