[sdiy] Clock signal detector

[johnspeth at yahoo.com]

Probably the most expedient way to detect the signal you described (must be about 4 Hz, must be about 15% DF) is to use a microcontroller.  It would constantly monitor the characteristics of the input signal and make a few decision if it's valid.  Any of the internally clocked micros would easily serve as a one chip solution.
If your criteria are less strict (for example any pulse width 3.5 Hz or higher), Scott's one-shot suggestion is usually how it's done.  You might be able to concoct some sort of one-shot using the circuit elements you have left over.  You'll certainly need to hand pick the timing components to get it to work.
JJS


----- Original Message ----
From: James Dunn <james at 4thharmonic.com>
To: "synth-diy at dropmix. xs4all. nl" <synth-diy at dropmix.xs4all.nl>
Sent: Monday, August 25, 2008 7:20:43 AM
Subject: [sdiy] Clock signal detector

Hi,

I want to make a simple circuit to detect when a clock signal is 
present. The clock line is either at 0v or a pulse of about 15% duty 
cycle and around 4 hz. I want a control output of 1 for clock present 
and 0 for no clock present. How is this done? It would be great if I 
could do it with 3 or 4 schmitt triggers and/or 1/4 of a 4016 analogue 
switch as that is what I have left...!

thanks

James
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