please help me with my first stomp box

[oscar]

Hello,
This effects building is harder than i expected. I am trying to make a silicon fuzz face, i am using the instructions on generalguitargadgets.com. For a while i wasn't getting any sound, then i got sound when the circuit was bypassed, now i have managed to get a hiss/hum sound out of the circuit. Please suggest what could be wrong, at the moment i don't have a multimeter just a contact indicator i made from an led. I have read all the faq but maybe ive missed something, sorry if this is a common question.
Thanks,
Oscar

[smoguzbenjamin]

You'll need to measure transistor pin voltages. Go get yourself a multimeter, measure the transistor pins and post them here so we can help you out a little better

[oscar]

How do i know which pin is which?
Thanks,
Oscar

[niftydog]

How do i know which pin is which?

go to google.com, search for the transistor part number and try to find a data sheet.

For example.  If you're looking for a 2N5088 transistor, type in "2N5088.pdf" and you should find a data sheet straight away.  These are generally in .pdf format.  The data sheet will tell you which pins are which.

Then it's just a matter of cross referencing it with the scematic, and measuring the voltages from each pin to the circuit ground or common.

[smoguzbenjamin]

try it without the .pdf bit and you'll find a lot more useful information By the way, it might be a good idea to familiarize yourself with the transistor pinout before actually building something. You might just have put the transistor in the wrong way, this could also be causing your problem.

[oscar]

right, ive put the transistors in the wrong way. I've got a meter now so ill post the readings when i put the transistors in the right way.
Thanks,
Oscar

[oscar]

here are the readings, i dont think they dont look right.
Q1- C=0  B=0.6  E=0
Q2- C=0  B=0    E=0

[smoguzbenjamin]

You're right, they look bad. First of all, the collector should be close to V+. On Q1 the Base is 0.6v above the emitter at 0v which looks OK. The second transistor. Well... Either you're meauring wrong or you just made a huge amount of cold solder joints. Check all joints for continuity, make sure you components are OK and that you are measuring right. It would be real helpful if you had a pic of what you were doing by the way.

[oscar]

I dont think there are bad connections because ive tested them all. i may be measuring wrong though. I am mesuring with one lead on the pin i'm measuring and one lead on the main bit of the transistor.
Thanks
Oscar

[Jason Stout]

I think your readings are correct, however not very useful. Measure the voltages with the negative probe connected to ground and the positive probe touching the transistor leg you wish to measure voltage across.

[oscar]

I have just re measured them properly and this is what ive got.

Q1  C=18.2  B=17.4  E=18.9
Q2  C=17.8  B=18.8  E=19.1

They seem very high but i measured the battery on its own and it is giving out almost 20v.
Thanks,
Oscar

[oscar]

It works! My 0.1 uf capacitor was a 15v one i changed it for a higher voltage one and now it works. Great! Thanks for answering all my questions.
Oscar

[oscar]

I get a howling sound when i turn the fuzz up to full. Does anyone know what this could be? Thanks,
Oscar.

[zener]

First, I'm wondering how those voltages reading from your transistors reached that high. You migh have misread it. Set the meter dial at the scale of 10 for DC and took the measurement using the 10-scale reading(if yours is an analog one). Are you using a 9V battery?

What transistors are you using? 2n3904? if yes try 2n5088 or 89 or other silicon that is more quiet.

Got the right pot value for fuzz control?

[smoguzbenjamin]

20V from a battery that delivers 9.3v at best is rather wierd.

[oscar]

i looked very carefully when i took the readings. it is an analog meter and i set it on the 50 scale and it read nearly 20v, i tried another battery on the same scale and it read 9v so i can't explain it, but the fuzz works. Its ok now, i have tidied up the soldering and put it in an enclosure.
Thanks,
Oscar

[smoguzbenjamin]

Congrats on your build!

But a battery supplying 20v is insane! It's obviously the battery if another one gave you 9v... :? I would consider a digital multimeter if I were you because they're easier to read out.