Simple Harmonic Jerkulator Questions?

[eliktronik]

Does anyone know where the input should be hooked up for the following circuit:
http://www.runoffgroove.com/harmonic.html

Also, what values should the Gain/volume pots be??

Sorry for the really basic quesitons, but I just haven't been able to figure this out. Thanks.

[doug deeper]

gain lug 2

[eliktronik]

Thanks!

[PB Wilson]

I just recently asked Brian Tremblay what he used and he told me 100K linear for Gain, and 100K audio for Volume.
I'm planning on building this up soon and trying out some different transistors. I'm also toying with an idea Brian shared about adding a switch to connect/disconnect the diodes found in the original Perculator. He said that there was a big difference in volume between the two settings on his pedal, so "on the fly" changes might not work, but it sounds like an easy way to add a new sound/texture to the pedal. Let me know what you think when you build it up. It looks like an easy and fun project.

[Tim Escobedo]

You can find the circuit here.

The gain and volume pot values aren't really critical. Between 100k and 1M would be OK.

I should update the circuit. I find the 22µF cap going from the emitters of the transistors to ground should probably be about 100µF for best stability. Otherwise, it may have a tendency to oscillate if the input gets grounded (such as when the guitar volume pot is turned all the way down).

All different kinds of diode combinations can be used. I'm currently favoring two high hFE transistors for this function.

[Ammscray]

I like the sound of the pedal but it's incredibly noisy...any suggestions without changing the tone?

[B Tremblay]

I like the sound of the pedal but it's incredibly noisy

What transistors are you using?  Mine is pretty quiet using a metal can 2N2222A (from an electric wheelchair) and a 2SB175 (from an old AM car radio).

[Ammscray]

I like the sound of the pedal but it's incredibly noisy

What transistors are you using?  Mine is pretty quiet using a metal can 2N2222A (from an electric wheelchair) and a 2SB175 (from an old AM car radio).

I've built a couple, all using Motorola 2N3904's and 3906's like in your scheme...maybe it's just inherent in the circuit but compared to my axis fuzz and other boosters like the mini-booster and such, I would never be able to use it live...I never tried a germ in it but I don't usually like hybrid circuits...I liked the HJ because it sounds like the axis fuzz a little but with less bass so it's good for humbuckers and P-90's...there's just that background wall of noise that I don't think I've heard in another pedal...

BTW Tim, I'm not a "quiet pedal with no noise" freak at all...noise doesn't usually bother me, it usually has to be alot to get my attention...

[eliktronik]

Thanks for the info everyone. I breadboarded it w/ a 2N5088 and a 2N3906 and it wasn't really my style, so I just took it apart. Maybe it was b/c of the transistors.

[Doug H]

In case anyone's interested, here was my stab at the Perc from a year or so ago:



This was based on discussions on the forum with Alf and others, hints dropped by the cloner (Chuck Collins), testing with the breadboard etc. Jason was kind enough to send me the Si and Ge transistors it used. (If anyone knows where he is, please let me know, I lost his address in a computer crash and have some 1n46's for him.) I liked the 1n46 diodes because the 1n34a's a)weren't right (according to the cloner) and b) limited the output too much for my taste. The 1N46's give a smooth Ge breakup but have a higher fwd voltage drop, so they give you a hotter output level.

With the "right" transistors it does produce a fat fuzztone and cleans up well. But in the end, it just wasn't that big of a deal IMO... It didn't really distinguish itself that much from other stuff I had already built.

Doug

[Tim Escobedo]

Don't know why the Jerkulator would be too noisy. The couple I built were about as noisy as comparable two transistor fuzzers. Perhaps Ge diodes (if they're being used) make it noiser since they limit the output, demanding the output volume be turned up much higher to compensate?