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PWM Hit And Hold Solenoid Driver Using CD4093

Reviews 4.50 star(s) 2 reviews

Certainly a different way of doing it, but it has been patented.
I was a co-author of a patent (#4,797,779) back in the late 80's that did exactly the same thing with lock solenoids for the company I was working for at the time (Folger-Adam Co.). My design used an LM556 (dual 555 timer) to make it happen. We did use an intermittent duty DC solenoid at full current @ 0.2 Hz and maintained hold with a PWM at 16KHz. Both duty cycles were around 20%
Being that it was used in a security type function, the initial full current pulse was re-applied every couple of seconds to make sure the solenoid was properly seated.
crutschow
crutschow
Is that patent now expired?

Certainly it can be done with a 556, but I believe this circuit is simpler and cheaper. :-)

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