Replacing a Potentiometer by a Tap-Tempo button?

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nammy
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Post by nammy »

hey,
I put my question here, cause of a CHEAP tremolo i bought (joyo JF-09 tremolo)
This pedal have only two potentiometer as settings = an Intensity one, and a speed one.
The speed one change the speed of the oscillation.

Is it possible to change that speed potentiometer by a tap-tempo button?
It would be a really epic improvement for a cheap pedal!

If possible some explainations would be really welcomed, like how to replace it? And i guess there are many way a potentiometer can act on a "clock" by default so also maybe what to replace?

Thanks a lot!

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andrej
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Post by andrej »

It is possible, but it's easier to make a whole new pedal. It also involves non-trivial MCU programming. If you're not a programmer, it's absolutely not worth your time.

Tremolos (and phasers, filters) with tap tempo usually have a microcontroller (MCU) generating their LFO, which is usually output by a DAC or fed into a digipot. The DAC route involves using the output voltage to control an optocoupler/optofet/OTA. The microcontroller can also generate high frequency PWM to control an analog switch, which makes a 'synthetic resistor' you can use in your tremolo/phaser/filter.

The other way would be having a microcontroller control a traditional LFO circuit, either via a DAC or a digipot. I guess that kind of circuit would have to involve sampling the output of your LFO with and ADC to correct the frequency, sort of a negative feedback. That or using a DCO kind of principle, making a digital ramp core for your oscillator. Never seen this principle used in guitar effects.

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nammy
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Post by nammy »

ughhh.
Thank you for your answer...
Since the current tremolo speed is only controlled by a Potentiometer, i really though it would be easier to achieve than that.
I think its too bad, but i will have to stay with that regular tremolo that is going out of tempo while playing with my bands (nooooo it is not the drummers fault xDDD)

Thanks again for your time anyway!

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