Article
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.
Materials
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.
Component list
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
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