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electronic switch

Hi, i'm a bit new to electronics. I was wondering if its possible to turn on the flow of current by another electrical signal. Yes, i know about transistors and relays but these switches turn off as soon as the second current is stopped, how to make this change in switch permanent, i'll be precise, i'm working on a laser alarm system, and it works fine, but the thing is that when i block the laser, sure the buzzer goes off, but when the obstruction is moved, the buzzer turns off, how can this be kept on until turned off manually by a switch. i know it must be quite simple but i dont know, please help
thanks

Monostable flip flop.
Activates with the signal for buzzer and you reset it manually.
Same for a small relay.

walee (author)  Downunder35m19 days ago

exactly, thanks alot