Editing 555 timer for 60% interval change

Thread Starter

J7NF

Joined Mar 12, 2016
18
I need to edit my 555 timer in astable mode to get at least an interval change of 60% for the duty cycle, for example varying from 40 to 100% and so on. I am using a 10k potentiometer and 1 K resistor as R1 and R2 so I cannot go below 52 %. Any idea
 

Dodgydave

Joined Jun 22, 2012
9,459
Lets have a circuit diagram first , then we can see what you need. You can do it with an hysterical circuit using diodes.
 

crutschow

Joined Mar 14, 2008
25,432
Below is a 555 astable design whose duty-cycle variation is close to 0-100% with pot position.
(Shown for pot positions of 1% and 99%.)
Edit: Either the OUT pin or DIS pin (with pullup) can be used as the output.
The frequency is approximately 1/(0.73*Rpot*C2)

upload_2016-4-4_16-17-25.png
 

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