[sdiy] audio control of momentary sw

[Stewart Pye]

Hi Adam,

Instead of the CMOS switch you could use a phototransistor optocoupler. 
I've used them before on a key scanning matrix. You just have to put the 
emitter on the row that is being pulled low, and the collector on the 
column that is being read (where the pullup resistor is). 

If you have high enough level coming in you may be able to just drive it 
with an NPN transistor. That would be one small chip, a transistor and 
a  couple of resistors.

Regards,
Stewart.


Adam Inglis wrote:
> What's a neat simple way of interfacing an audio signal to close a 
> momentary switch?
>
> The scenario is: I'm wanting a dedicated track of audio pulses on my 
> DAW to replicate the front panel momentary switch on an old Casiotone 
> keyboard. The switch closes a matrixed line (5 volt signal) that is 
> polled by the CPU ("pattern stop - start").
>
> I'm thinking an op-amp to a CMOS bilateral switch. Any one-chip 
> solutions?
>
>
>
> regards
> Adam Inglis
> http://www.adambaby.com
>
>
>
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