555 timing cicuit need help

Thread Starter


Joined Aug 3, 2010
hi all

there is more than likly a circuit out there for what i want to do. i have an inverter project that i'm working on that has a 12V draw of about 1000 amps. the 12V side is more than capable of handeling this but is shuting down the low voltage protection on start up. i need a simple cicuit using a 555 timer that will hold the output low for 30 seconds and then keep the output high untill the inverter is turned off, to give the 12V side time to power up properly before allowing the inverter to draw any current. i alredy have the mosfets to handel the current draw for switching on and off.

thanks steve


Joined Dec 7, 2008
This is a mono stable you can use. Just calibrate the pre-set for 30sec. If you want to use a transistor then replace the relay with a PNP transistor
You can also use the relay by connecting your devise to the normal close contact of the relay and then place the relay between pin 3 and 0v