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Tremolo Thudding

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7/24/2000 9:16 AM

Tremolo Thudding

I'd like to post this question again, since most everybody thought Chris was talking about the popular tremolo that Hair Bear posted from the Australian mag a while ago.

Here's the link:

http://www.xavax.com/efm/pdf/tremelo.pdf

I have posted this link on my site with an extra PCB gif, but this is not the first time that someone has had trouble with loud background noise (thudding with the beat of the trem) in the circuit. Anyone knowlegdable about tremolo circuits? Is there something in the layout or circuit that makes it susceptible to noise?

With so many other trem circuits available, I'm wondering if I should pull this one off the site. The nice thing about this one is that all the parts are available at Radio Shack (if you can find a well stocked store). Of course that don't count for much if ther durn thing don't work

7/24/2000 12:45 PM

I havn't built this particular trem, but a common failing of trems is to pick up a spike from the oscillator, and transfer it to the rest of the ckt via the power rail. Often a 470ohm isolating resistor & a cap across the power rail will do good.
Or in this case have a separate 100 ohm & cap for the two chips. Another thing is, that if a triangle control voltage sneaks into an audio output, you hear it at the spiky points, where you dont hear a sine wave. So maybe you could smooth the tops of the triangle with a pair of back to back diodes.

7/24/2000 2:41 PM
SpeedRacer	sounds like LFO leaking into the audio out.. try some HPF action.

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