[sdiy] VCO waveform logic selection

Dave Manley dlmanley at sonic.net
Wed Sep 12 18:06:31 CEST 2007

>> Are the protection diodes built into the device inadequate for this 
>> purpose?
> Those diodes delimit the amplitude to +-0.6V around GND, while the input 
> protectors do clamp against Vcc and GND. Delimiting the swing at the 
> open switch does reduce the risk of capacitive crosstalk.
> Cheers,
>   René

Ahhh, thank you...I see I completely missed the point.  The open switch 
is not connected to the virtual ground, and so it swings with the input 
signal.  The diode clamps to ground limit this swing.

The follow-up question then is with a typical +/-5V swing on the 
unconnected input how much of that signal appears in the output?


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