[time-nuts] Re-triggerable Monostable?

Hal Murray hmurray at megapathdsl.net
Thu Oct 25 15:12:06 EDT 2007

> I'm working on a synth. project which can take either an external
> 10MHz 
>   reference input or use an internal TCXO.  It would be nice if the
> presence (or more importantly, failure) of the external 10MHz ref.
> could  be detected automatically, and signaled to the user.

Are you happy hacking low level software?  (aka firmware)  If so, consider 
one of the tiny micros.

The PIC 12F629 comes in an 8 pin DIP.  It doesn't require any external 
components.  (Maybe a socket.)

It's got an 8 bit prescaler on Timer0.  That would drop 10 MHz down to 
something you could watch with software.

You even have a couple of pins leftover for other hacks.

I think there are similar chips available in SOT-3-6 if space is critical.

These are my opinions, not necessarily my employer's.  I hate spam.

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