project help~

Thread Starter

xiaoboi

Joined Jan 19, 2011
2
I need to design a DC fail safe supply system.

My main voltage is 24V. When my main voltage fails below 24v (22v and below), a LED will be lighted up and a buzzer will sound. After 3 seconds, the supply will be switch to the standby voltage and the buzzer will go off (using a relay).

anyone? :(
 

RRITESH KAKKAR

Joined Jun 29, 2010
2,829
Use ic like 741, by this you can setup yours ref. voltage like 22V less than it the o/p will be high then using 555 stable mode you can set time.
 
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