Circuit to Convert Random Spikes to Square Waves

[Pommie]

This reminds me of early electronic rev counters. The width of the pulse from wherever (the points for example) varied. The solution was a monostable to make the pulses a fixed width.

Mike.

 

[philomel]

I don't know what you are really asking but a monostable Multivibrator comes to mind, a oneshot. It will put out a fixed pulse when it detects a spike. The pulse width should be less than the timing of the pulses.

 

[pnielsen]

The original spikes average 10mS. I constructed a standard LM555 monostable with 10uF and a 5K trimmer for the RC values.

http://www.ohmslawcalculator.com/555-monostable-calculator

It detects the spikes, makes them all the same amplitude, but the duty cycle at pin 3 is exactly the same as the spikes. What I wanted was for each cycle to stay "on" longer as per my previously uploaded diagram. Can anyone please suggest how to do this?

 

[Grossel]

Tired of just lurking around on tis forum. Here is my thaught on how to resolve the issue - What I would have done.

You need two 3 major components: A custom integrator, that is able to reset itself, and a custom built mono stable flip-flop that has one extra input where voltage tetermines the holding time. Those two connects, and a back coupled inverted output (*) from the mono-stable flip flop to the reset of the integrator. * Probably need another monostable flip-flop that activates by negative flank to avoid integrator being disabled by reset input.

 

[pnielsen]

Oh my. Now I am in trouble. May need to reassess my needs to avoid a whole additional circuit board.

Can anyone offer a simpler, or compromise, design approach?

 

[Pommie]

If the monostable doesn't work then you have something wrong. Are the spikes large enough to trigger it? Are they too large and you need a resistor divider?

Mike.

 

[AnalogKid]

Start at the beginning. What are the amplitudes of the tallest and shortest spikes you want to capture. Note - the lower the short spike limit, the low-level noise triggers there will be.

ak