Simple Circuit Concept

[Sandman101]

Hey all,

It's been a long time since I've done discrete electronics and I'm in need of a discrete solution (with logic gates):

I have a switch, that once opened, a circuit is "turned on" and runs. If the switch closes, it cannot affect the system. Sorta like an alarm .. when you break in, the alarm shouldn't shut off once the door has been closed !

Any help is appreciated!

Thanks!

 

[MP1]

Probably looking for a RS Latch. Once set, you have to pulse the reset line to change state. There are chips available, or you can build one with gates.
Hope it is helpful.

MP

 

[hotwaterwizard2]

How about an SCR?

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