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how to generate a single pulse from a switch closure

if I close a switch (non momentary) how can I trigger a 555 by
generating a single pulse?

example: relay contacts close, debounce the closure, generate a pulse
triggering a 555.
 
R

Rich Webb

Jan 1, 1970
0
if I close a switch (non momentary) how can I trigger a 555 by
generating a single pulse?

example: relay contacts close, debounce the closure, generate a pulse
triggering a 555.

Basically, by with a capacitor on the trigger input so that the 555 is
sensitive to edges, not levels. Google for "555 edge trigger" for
examples.

There are software packages (e.g.,
<http://www.schematica.com/555_Timer_design/555_Timer_PRO.htm>) that
could help as well.
 

neon

Oct 21, 2006
1,325
Joined
Oct 21, 2006
Messages
1,325
What you describe is a monostable lm555. USE pin 2 to trigger once it fires another pulse doesn't reset it not until the set time expires. There are gabs of info on this timer.
 
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