Mandroid possible trigger citcuit for the up/down

[mikef]

  I was wondering if some small timing circuit, say a simple 555 type deal, hooked up to the "TGU" / "TGD" /ground on the circuit might give you a  sequencer type function? a foot switch to turn it off and a pot to change speed and a toggle switch to change direction? What say ye all? 9Or Y'all in my neck o the woods.) Thanks!

[mikef]

I see synthroteck has a little 555 timer kit............ https://www.synthrotek.com/products/lo-fi-synthesizer-circuits/555-timer/

[mikef]

a toggle switch  between TGU and TGD and  the Pot on the 555 should  control for speed...........

[diablochris6]

I'm just spitballing here, but wouldn't the 555 LFO have to go to ground? I believe the main IC of the Mandroid relies on grounded or not grounded to achieve the change between settings? Would it matter if the LFO is applying voltage to the IC?

I don't have answers to this, but something tells me that there could be an issue with the way you are going about it. There might be some other way though...

[diablochris6]

Maybe you can hook up the TGU or TGD pin to the source pin of a JFET, have the drain pin go to ground, and use the LFO voltage to trigger the gate? It would be kind of like using a FET bypass system, but instead of a footswitch connecting the gate to voltage, the LFO is doing it.

[mikef]

Thanks Diablo,( Had to set that aside and finish up some other stuff)
,but seems like a good way to go!