Hi guys,
I'm working on this small project for a pulse timer. I have a small machine with NO switch that I want to connect to the timer . This way the switch will produce a rising edge and the contacts will have to open and then closed again for another rising edge. So if the switch contacts are held closed forever the timer would produce only one pulse to energize a relay and hold it for a specified period (Determined by R2 and C1) and then release.
Part of the circuit (the part with the 555 timer) is off the net and I'm not quite sure how it works. Specifically C3,R5 and D1 were added so that the switch being closed continuously would have no effect on the 555. It was described this way in the circuit instruction:
"a capacitor can be used to isolate the switch so that only the initial switch closure is seen by the timer input and the switch can remain closed for an unlimited period without effecting the output".
Thanks
Kal
I'm working on this small project for a pulse timer. I have a small machine with NO switch that I want to connect to the timer . This way the switch will produce a rising edge and the contacts will have to open and then closed again for another rising edge. So if the switch contacts are held closed forever the timer would produce only one pulse to energize a relay and hold it for a specified period (Determined by R2 and C1) and then release.
Part of the circuit (the part with the 555 timer) is off the net and I'm not quite sure how it works. Specifically C3,R5 and D1 were added so that the switch being closed continuously would have no effect on the 555. It was described this way in the circuit instruction:
"a capacitor can be used to isolate the switch so that only the initial switch closure is seen by the timer input and the switch can remain closed for an unlimited period without effecting the output".
Thanks
Kal
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