[sdiy] trigger to optocoupler is button?

[Dave Magnuson]

Hi Jean,

I've added trigger inputs to a toy drum machine.   I didn't use 
optocouplers, but simply strapped a transistor across the button contacts of 
the toy.   Apply a positive trigger through a series resistor to the base of 
the transistor.

Look for a "gate to S-Trigger converter" schematic... same idea.   You just 
need to figure out the voltages at the switch (does it short to ground or 
V+) , and orient the transistor the in proper direction.  This is the same 
principle as your opto coupler idea... just without the added isolation.   I 
haven't had any problems thus far...

You could also use CMOS switches and use those to short the button 
contacts... just be careful that your switching voltage doesn't exceed the 
supply voltage of the CMOS switch (use protection diodes, etc.).   The nice 
thing here is that you get multiple gates on a single IC.

Dave Magnuson

----- Original Message ----- 
From: "Jena Jena" <jena_mu_six at hotmail.com>
To: <synth-diy at dropmix.xs4all.nl>
Sent: Friday, January 20, 2006 1:30 PM
Subject: [sdiy] trigger to optocoupler is button?


> Hi there,
>
> I would like to trigger some buttons on certain musical toys I have, using 
> the triggers of my modular.
>
> Can I use an optocoupler for that?
>
> If so what type?
>
> If not..............any other suggestions are very welcome.
>
> Thanks...
>
> Greetings,
>
> Jean
>