Manual speed/pitch pot on Payback 1.0?

[Taylor]

I'm building a Payback 1.0 right now. Schem here. I want to add a manual pot to control sample rate/speed/pitch. This is done by lowering the supply voltage to the ISD chip. There was some talk here:

http://www.diystompboxes.com/smfforum/index.php?topic=46680.msg459336#msg459336

I'm wondering how to implement this. I'd rather not have to switch between vibrato and manual - I'd rather have both functional at the same time. Could I just put a pot as a variable resistor between the 5v supply and the point where 5v is injected to the 2n5088?

[The Tone God]

I'm wondering how to implement this. I'd rather not have to switch between vibrato and manual - I'd rather have both functional at the same time. Could I just put a pot as a variable resistor between the 5v supply and the point where 5v is injected to the 2n5088?

Yes you can put a pot between the vibrato circuit and the ISD. You have to be careful though because if you go too low voltage wise the ISD will lock up.

Andrew

[Taylor]

Princess Di, when it locks up, does it just need to be power cycled, or is it a more serious fate? I have played with PT2399s where using a huge time pot slows it way down to get long records, but it would sometimes die completely doing this. I want to make sure I won't actually damage the chip as they are expensive and hard to find.

[The Tone God]

Princess Di, when it locks up, does it just need to be power cycled, or is it a more serious fate? I have played with PT2399s where using a huge time pot slows it way down to get long records, but it would sometimes die completely doing this. I want to make sure I won't actually damage the chip as they are expensive and hard to find.

No its not serious, the ISD just needs to be cycled. The internal controller screws up when the voltage is dropped and does not recover cleanly. The recorded audio is not lost.

Andrew