I found and interesting sound but why?

[oscar]

I put a new battery in my homemade fuzzface yesterday and when i turned it on it made a continuous electronic noise a bit like a synth. The volume nob contolled the volume of the sound and the fuzz nob controlled the pitch. It sounded awfull when i played through it but it could be usefull for making those sounds on it's own. I checked the battery i put in and i got a reading on my multimetre of 20 volts! This is the only thing i can think of that may have caused it. The fuzz box has now gone back to working like normal. I only got this wild sound for about 5 minutes.
I would like to know how i can control this sound i found so that i can use it musically. Any insight would be much appreciated.
Thank you,
Oscar.

[sir_modulus]

I believe thats ossilation (high freq) and is reffered to as whine. I am as confused as you when it comes to why it occured and went away. Thats odd.

Edit: did it suddenly dissapear or did you do something (even something small) to it before it stopped (like hitting it or something)?

[Samuel]

If you want a controllable version - try putting a pot set up as a variable resistor in series with the power source, as you crank it down and "starve" the transistors for power you often get the same effect. It's worth a try, anyhow.

[oscar]

What happened was i turned it off then turned it on again and the sound was gone.
Thanks.

[guitarhacknoise]

the part that I don't get, is that the battery read 20v.
what was the reading after the whine stopped?

[sir_modulus]

maybe somehow, you drove the trannies into DC amplification (somone may correct me here as i might be wrong.), and amplified the 9V into 20V.

[oscar]

The battery was not connected to the circuit when i tested it. I have not tested the battery now the whine has gone. This is off topic but earlier i combined my fuzz with my boss OD3 and got a really over the top guitar sound with amazing almost infinite sustain. It was great fun, ha.
I can always get some whine when the fuzz is turned to max but i don't get the pitch control like i had before.
Thanks,
Oscar.

[travissk]

I'm not sure where the 20V was coming from, but if you're running the opamp at 9V/Ground rails, then even if you have DC amplification you're going to be limited by a voltage slightly less than your rails.

It seems something was oscillating in there; it can happen with an incorrectly designed negative feedback section or for many other reasons, most of which I don't know . Could anything have short-circuited?

There are some searches you can do online for oscillator circuits, but also take a look at some schematics - the EH Microsynth might use one, and I'm sure the commonsound.com kits for some of the synth-like pedals (i.e. triwave) have oscillators you could take a look at.

Art of Electronics chapter 5 (?) is on Active Filters and Oscillators if you have that book.

[toneman]

mayB U had meter set to "ohms"(?)
read manual.
fuzz boxes do *not* turn 9V into 20V.
if U've found a way 2 do this,
call the power company and sell it.
tb

[guitarhacknoise]

:shock:  wait, wait, wait,................

oscar
PostPosted: Sat Sep 04, 2004 5:22 pm    Post subject:
The battery was not connected to the circuit when i tested it. I have not tested the battery now the whine has gone.

still, how did a 9v battery measure 20v.?

[Hal]

do _all_ of your 9v batteries measure 20v?

[Travis]

A low/dying battery in a DMM will sometimes give this type of result.

[oscar]

Yes the other batteries were the same. They are from a bulk Samsung pack i bought. I suppose it is possible that something short circuited when i replaced the battery and has now been knocked out of contact. I will have a look at those schematics Travissk,
Thanks,
Oscar.

[zachary vex]

i was thinking the same thing about your meter... sounds like you might have a dead battery in the meter.  also, i thought you might be seeing 2.0 volts but the meter isn't showing the "." very well (when my meters start to die, the liquid crystal display stops having good contrast).