Car-Bulb Flasher Circuit

Description 

This astonishingly simple circuit allows one or two powerful 12V 21W car bulbs to be driven in flashing mode by means of a power MosFet. Devices of this kind are particularly suited for road, traffic and yard alerts and in all cases where mains supply are not available but a powerful flashing light are yet necessary.

Circuit Diagram:

Parts:

• R1 = 6.8K
• R2 = 220K
• R3 = 22K
• C1 = 100uF-25V
• C2 = 10u-25V
• D1 = 1N4002
• Q1 = BC557
• Q2 = IRF530
• LP1 = 12V-21W Car Filament Bulb (See Notes)
• SW1 = SPST Switch (3 Amp minimum) 

Notes:

• Flashing frequency can be varied within a limited range by changing C1 value.
• As high dc currents are involved, please use suitably sized cables for battery and bulb(s) connections. 

Source http://www.extremecircuits.net/2009/07/car-bulb-flasher.html