Adjustable duty cycle for a 555 oscillator?

Thread Starter

JulesP

Joined Dec 7, 2018
205
Hi there,

I have a simple 555 signal generator (circuit attached) that, using a series of adjustable trimmers, I can get an output of a variety of frequencies, e.g. 200Hz, at around 12V.

However, the output waveform (see attached) has a duty cycle of about 60% but I would like this to be adjustable from 30-60%.

Is that doable with some straightforward modification to the circuit?

Thanks

Jules
 

Attachments

Thread Starter

JulesP

Joined Dec 7, 2018
205
Thanks for that Sam. With that design can I also go above 50% if needed?
Has the design been withdrawn for some reason?

Julian
 

Thread Starter

JulesP

Joined Dec 7, 2018
205
Lol. Sorry I saw the SamR at the bottom of your reply.
I have read the relevant section and it seems straightforward but what diode spec is Ok?
I have plenty of IN4007s so would the be fine?

Jules Verne
 

MrChips

Joined Oct 2, 2009
21,161
If you would like to control frequency and duty cycle independently you can follow the 555-timer with a monostable multi-vibrator circuit such as 74HC123, CD4098, CD14528 or CD14538.
 
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