Mutchus

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

How to build varying brightness AC bulb circuit.  In this circuit, an SCR is used to slowly vary the intensity of a 120 volt light bulb by controlling the time that the AC line voltage is applied to the lamp during each half cycle. Varying brightness AC Bulb Circuit Diagram: Caution: The circuit is directly connected to the AC power line and should be placed inside an enclosure that will prevent direct contact with any of the components. To avoid electrical shock, do not touch any part of the circuit while it is connected to the AC power line. A 2K, 10 watt power resistor is used to drop the line voltage down to 9 volts DC. This resistor will dissipate about 7 watts and needs some ventilation. Operation: A couple NPN transistors are used to detect the beginning of each half cycle and trigger a delay timer which in turn triggers the SCR at the end of the delay time. The delay time is established by a current source which is controlled by a 4017 decade counter. The first count (pin 3...