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555 timer circuit help

stevenc_hmfc

Aug 25, 2011
1
Joined
Aug 25, 2011
Messages
1
Hi, iv built this circuit but the relay is constantly closed. I want it to be closed for a set amount of time. Any ideas if somethings wrong? Thanks

lightingcircuitjpg2.jpg
 

JoeyAVR

Aug 25, 2011
16
Joined
Aug 25, 2011
Messages
16
Are you sure that the relay isn't wired wrong and staying permanently open?

With the load on the low side of the mosfet the gate shouldn't be getting enough volts to turn on in the first place.

Put the relay between the mosfet and 12V instead.

There's no smoothing capacitor on the supply rail, which won't help either. use at about 100uF, close to the 555,

Joey
 
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