Article
Led Flasher
A flashing LED based on a 555 is not likely to win the first prize for originality, but such a circuit continues to be useful for all kinds of applications. The thing that makes this version special is the very low current consumption, because the LED flashes only very briefly each time (dutycycle of only 10%) and because it was specifically designed to serve as a (fake) alarm indicator in a car. The circuit has been configured such that the flashing only starts when the ignition is switched off.The latter could have been achieved in the usual way with the aid of two resistors and a transistor connected to the reset line. But by using a clever trick instead, this has become even simpler.
Gerber file
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PCB
Component list
Resistors:
R1 = 470kOhm
R2 = 1MOhm
Capacitors:
C1 = 100nF
C2 = 220nF
Semiconductors:
D1 = LED
D2,D3 = 1N4149
IC1 = 555
R1 = 470kOhm
R2 = 1MOhm
Capacitors:
C1 = 100nF
C2 = 220nF
Semiconductors:
D1 = LED
D2,D3 = 1N4149
IC1 = 555
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