Long delay light flasher

[muckleluck]

I need to build a light flasher to test brake lights in cars. The input voltage is 14V and the max current about 3A. The light needs to be powered for 30s-1min (adjustable whether by a switch or a pot doesn't matter)  and then off for 30s-1 min. Anybody have any suggestions for a simple circuit that can meet these specifications?

Muckleluck

 

[muckleluck]

I decided to us an astable 555 timer circuit  with a 1M ohm pot and a 100 microF cap to (hopefully) give me the correct timing range. What I can't figure out is which transistor to use to switch the current to the lamp. Does anyone have any suggestions? I might need to switch up to 8A. Am I on the right track with this or is there an easier way?

 

[Alun]

I agree except I wouldn't bother with a relay I'd use a power MOSFET, the IRL540 would be perfect for this application.

 

[muckleluck]

sweet. thanks for the help guys.

 

[muckleluck]

Oh wait... so you mean I should use a transistor and a power mosfet or can I drive the mosfet directly with the timer output?