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Bicycle Rear Light

One Super LED and 10 Components Last 5 Minutes

Fitting a bike with a rear light that stays on even when stationary is both useful and interesting — especially when it uses a circuit as simple as this. The small circuit is stripped right down to the bare essentials, but stays on for 5 minutes.

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Materials

ELEX-PCB.pdf

Extra info / Update

Note: Since the original publication of this project/article, some of the components, software elements, webpages and other elements might have been updated or changed.

Elektor PCB Service

Elektor recommends the Elektor PCB Service service from its business partner Eurocircuits as the best services for its own prototypes and volume production.

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Bill of Materials

Resistors
R1 = 47Ohm
R2 = 1.2kOhm
Capacitors
C1 = 1F 5.5V, e.g. Panasonic EECF5R5H105
Semiconductors
D1 = LED, red, standard (Vf = 1.7V)
D2 = zener 5.6V 3W
D3 = LED, red, high brightness, e.g. MCL034URC (Imax = 20 mA)
D4–D7 = 1N4004
T1 = BC547B
Elex-1 (UPBS-1) prototyping board