Re: Analog Period Detector

On May 8, 8:38 pm, D from BC <myrealaddr...@xxxxxxxxx> wrote:
On Tue, 08 May 2007 13:10:27 -0400, John Popelish <jpopel...@xxxxxxxx>
wrote:

D from BC wrote:
I have a repeating analog waveform and I'd like to make a circuit that
gives me an OK light if it indeed it's repeating without change.
The circuit just checks if a V point is repeating with the same time
period.

For example:
If the frequency changes... no ok light.
If there is no signal ...no ok light.
If the signal locks high ..no ok light..
If the signal is overdistorted...no ok light
If the signal is repeating just right...ok light..

So far I've roughly come up with this:
A window comparator output supplies D input to a D flip flop which is
clocked by a 555 as a monostable which triggers at some voltage point.

I'm interested if somebody used a different circuit for a similar
problem.
Maybe there's an IC that does this already??

Can the OK frequency vary over a very wide range?

If the range of OK frequency is fairly narrow, a phase
locked loop, like a CD4046 with a very slow error filter
might have just about everything you need. Its in lock
logic output may be able to drive the indicator, directly.

You get to define hoe fast a frequency change is too fast by
how fast the error filter can change the tracking VCO.

http://www.ugcs.caltech.edu/~wkc5/tmp/CD4046B.pdf

Opps I should have mentioned the average signal frequency..
It's 120Hz... I don't think high speed electronics are required.
Also...
The tolerable f error is high...I'm guessing 10%..
For example..
A signal repeating at 120Hz+/-12Hz should give the ok light.

I remember playing with the 4046 years ago.. I like the idea and I'll
check it out..
Thanks


You can set the voltage controlled oscillator so that its total range
is the range you want the signal to be tracked, successfully. Are you
really concerned if the frequency changes above some rate within that
range?

John Popelish

.

Relevant Pages

  • Re: Analog Period Detector
    ... The circuit just checks if a V point is repeating with the same time ... A window comparator output supplies D input to a D flip flop which is ... how fast the error filter can change the tracking VCO. ...
    (sci.electronics.design)
  • Re: Analog Period Detector
    ... The circuit just checks if a V point is repeating with the same time ... A window comparator output supplies D input to a D flip flop which is ... If the range of OK frequency is fairly narrow, a phase locked loop, like a CD4046 with a very slow error filter might have just about everything you need. ...
    (sci.electronics.design)
  • Re: Analog Period Detector
    ... The circuit just checks if a V point is repeating with the same time ... A window comparator output supplies D input to a D flip flop which is ... how fast the error filter can change the tracking VCO. ... learn DSP programming just be skilled in those areas.. ...
    (sci.electronics.design)
  • Re: Analog Period Detector
    ... The circuit just checks if a V point is repeating with the same time ... A window comparator output supplies D input to a D flip flop which is ... how fast the error filter can change the tracking VCO. ... learn DSP programming just be skilled in those areas.. ...
    (sci.electronics.design)
  • Re: Analog Period Detector
    ... The circuit just checks if a V point is repeating with the same time ... A window comparator output supplies D input to a D flip flop which is ... how fast the error filter can change the tracking VCO. ... learn DSP programming just be skilled in those areas.. ...
    (sci.electronics.design)