Author Topic: Changing the Duty cycle of a given signal  (Read 138 times)

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Offline Spemo

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Changing the Duty cycle of a given signal
« on: April 14, 2021, 07:36:41 pm »
Hello everyone,

I'm trying to find a solid state solution for a small problem.

The situation is as follows:
A Timing circuit with a CD4060BE and a 4027BE, the output is a 1Hz signal with a 50% Duty cycle.
This 1Hz 50% signal goes into a "signal shortener" which is made up out of two DPDT relays, a transistor, capacitor and resistor, to shorten the signal to a short pulse, my guess is around 15% on,  85% off.
Now, I have two problems with this: first, relays. It works, but the noise it creates is not wanted. Second, there is reliability to think about.

I'm looking for a really simple solution that changes the duty cycle of the given signal from 50% to let's say 15%, or adjustable at best.

I've tried googling and the forum search, but I couldn't find the answer I was looking for.

Maybe there is an obvious solution for this... If you happen to know one, please share it with me, it would be apreciated a lot!

Thank you for your time,

Daniel
« Last Edit: April 14, 2021, 07:38:16 pm by Spemo »
 

Offline Renate

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Re: Changing the Duty cycle of a given signal
« Reply #1 on: April 14, 2021, 07:40:53 pm »
If you AND the last two bits of the counter you will get a 25% duty cycle.
If you AND the last three bits of the counter you will get a 12.5% duty cycle.
etc...
Or you can NOR them.
 

Online Ian.M

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Re: Changing the Duty cycle of a given signal
« Reply #2 on: April 14, 2021, 07:54:28 pm »
.... and if for any reason you cant tap into the counter, so have to work with the 1Hz 50% signal, you could use a monostable.

Are there any other constraints on the required output signal?
 

Offline Spemo

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Re: Changing the Duty cycle of a given signal
« Reply #3 on: April 15, 2021, 04:48:25 pm »
Hi!

The monostable, that's the solution I'm looking for!

Silly me, since it's already in a different part of the complete circuit, with a 555... Thanks a lot!
 


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