Help me make a digital circuit to detect if a clock is toggling or not

[rakko]

I want to make a digital circuit to detect if a clock is toggling or not. Basically, it outputs a "1" as long as the input is toggling and "0" if not? Sort of like a mono-stable one shot but using digital logic only. I know how to make the circuit to detect the toggling and output a "1" but once the clock stops, I need to reset my output. This is the part I havn't been able to figure out yet. Anyone done this type of circuit before? please :idea:

 

[mister_rf]

Re: oscillation detector

One idea:

**broken link removed**

More details here:
**broken link removed**

 

[rakko]

Re: oscillation detector

This is exactly what I need to do but unfortunately I don't have the 2nd clock. There may be other solutions to this problem such as delay lines and flops?!!!

 

[mister_rf]

Re: oscillation detector

A very simple oscillator can be made with three inverters. Any inverting CMOS gate or combination of gates could be used.

https://www.fairchildsemi.com/an/AN/AN-118.pdf

 

[BradtheRad]

Re: oscillation detector

Could a missing pulse detector be what you need? This is a typical application for a timer IC such as the 555.