Timmy clone whines...**EDITED**..fixed!

[alphadog808]

Hey guys,
  I have a timmy clone I built, and I notice it whines/whistles/squeals when I turn all the knobs up/high.  This is especially true as I turn up/down the treble knob.  I kinda poked around but didn't see anything suspicisous...well, some of the wiring is a bit long...any ideas what causes whining?  Any particular places to investigate?

[alphadog808]

A bit more info...
- doesn't matter if I use power or 9v
- tried a different op amp...same
- shortened wires...same
- reflowed solder...same
- tried plug in a different room..same
- tried different power supply..same
- tried headphones vs amp and a different amp...same.
- swapped out pot..same

I'm out of ideas.  :( The only thing I can think of is people don't run the Timmy at full vol and full gain.  If I don't dime out the vol and gain, the tremble whine doesn't seem to happen.

Side note, the while freq seems to change as I turn the pot left and right. If I turn it farther right, it stops, I assume because I'm cutting the treble frequency.  

If anyone has anything else to suggest, please let me know.

[JaviCAP]

Try the Timmy with a Boss or some other buffered pedal before and check if the whine is still present. If the squeal dissaperas= impedande. is the problem.

BR

[Vince]

I had an issue of high pitch whining too on both attempts when building the compact layout. I now build from this one and have never had squealing. Not sure why.

http://tagboardeffects.blogspot.co.uk/search?q=timmy

[alphadog808]

Vince,
   I didn't do the compact version, I figured more space would make my life easier.  

Javi, I'll try hooking it with a Boss pedal to check impedance.  IF it is impedance, how do I go about fixing it short of having to lug a boss pedal around with the Timmy?

I was also told by Mirosol to try swapping the 100pf cap with a 220pf cap.  The only bummer is if I do that, then it's not TRULY a 100% Timmy clone...but oh wells, I'm pretty much out of ideas at this point.  Thanks for the help guys!

[JaviCAP]

Well,  impedance problems are a real sh*t.

Finally, I discovered that using a buffer pedal at the begining of my chain is a great thing, no matter if you use two pedals or forty, so, since I had impedance problems with my Les Paul and the Rocket Animal, the Klon Buffer is glued to my guitar's output :)

BR

[induction]

The input of the Timmy is a non-inverting op-amp stage, so its input impedance is fairly high (>400k). I'd be surprised if it was a impedance problem.

Have you tried using shielded cable for any long wires (especially on the input side)?

[alphadog808]

Induction,
   The wires I'm using are not shielded.  I got the wires from smallbear, 22 gauge, I think it was.  Is shieled cable a must for all these diy pedals?

BTW, I'm not a big electrical guy, but if it was an impedance issue, wouldn't the whining be happening all the time?  It seems to only happen when I dime out the vol and gain and tweak the treble.  Seems to happen when the treble is between 10 and 2.

[induction]

I hardly ever use shielded wire. It's good for minimizing induced voltages that could cause noise or oscillation when amplified through a high gain circuit. I only suggested it because you're getting what sounds like oscillation, but it was just a shot in the dark. Timmy's gain is not that high, and I don't have shielded cables on mine. But I've never run mine at max on both volume and gain, so I don't know if mine has that problem or not.

To be honest, I suspect a solder bridge somewhere. But I'm just guessing again.

Have you tried mirosol's suggestion?

[alphadog808]

Induction,
   Since you have a Timmy/clone, can you try to see if you have the same problem?  Turn everything up to 10 and then work the treble knob back and forth.  You'll know for sure if you have the whining issue, it changes frequency as you turn the knob...like trying to tune into a radio station!  

Looking at youtube vids, I noticed noone(that I could find) ever turned their volume and gain up to full at any point in their demos.  Most people are looking for unity volume, I guess.  

If I had a solder bridge, wouldn't it not work at all or very badly?  The pedal seems to work fine otherwise.  I have run a hacksaw between the rails numerous times to make absolutely sure there aren't any bridges.  

Speaking of bridges tho, on the footswitch, in order to bridge 2 lugs together, I made a solder bridge..not sure if it matters, but I thought I'd mention it.

I am going to try and pickup a cap to try either tonight or tomorrow.  What will bum me out if it works is that the pedal won't be 100% same circuitry...

[induction]

I'll see if I can try it tonight. (I have 5 month old, so no promises. My time is not my own anymore.)

A solder bridge can cause any number of problems, or none. It's impossible to predict unless you know what's being bridged. I use short lengths of copper wire for jumpers, whether on the board or on the switch, but as long as you have a conductive pathway with no unintended shorts, an intentional solder bridge on the switch should be fine.

If you have an extra 100 pF cap sitting around, you can put it in parallel with the existing one, just as a  temporary check of whether it helps. The difference between 220pF and 100 pF in this position will be a slight reduction in the very high frequencies. Might be noticeable, might not, you can A/B it and see if you hear a difference, and if it matters to you.

[alphadog808]

Induction,
   I appreciate it!  And I understand about the time thing, I have a 14 month old, so I'm usually busy until we put him to sleep.  But once he's asleep, it's my time!  haha!

BTW, I'm able to repro this problem without a guitar plugged in, just pedal to amp.

I'm thinking the whining is specific to my build as when I do a google search, I don't hear anyone complaining about that...then again, I don't know why anyone would crank their volume knob unless they wanted an insane volume boost.  I did hear one user with a real timmy say he would catch radio stations on his Timmy, but he didn't mention if knob settings triggered it.  

Unfortunately, I'm just getting into this, so I don't have many spare parts lying around...yet!  I looked, but no dice.  I'm hoping Radio Shack has one!  

Thanks again in advance!

[alphadog808]

Got it working!  To close up this thread, this is what I did/found to stop the whining.  

1) Went with the 220pf ceramic cap over the 100pf cap
2) repositioned the input and output jacks; seemed to be better/worse in some locations.  By that, I mean I cranked down the nut while holding the jack in a certain position
3) Found out that the whining was MUCH more prevalent if I didn't have anything plugged into the input.  You'd think not having anything plugged in would cause less whining, but in fact, it made it worse.

I think what really made the most difference was 1, then 3, then 2.

Hope this might help someone else who might be pulling their hair out trying to silence their pedal/s.

Thanks to all who helped me through this, this is a great hobby!

[induction]

Great! Glad you got it fixed. I tested mine, and I found no problems at max gain and max volume. Must be a layout-sensitive circuit.

[alphadog808]

Thanks for testing it out on your pedal, I appreciate it!