• on Audio/Video/Photography
  • Published in issue 7/2005 on page 0
About the article

12-V Dimmer


Designing a dimmer for 12 V is tricky business. The dimmers you find in your home are designed to operate from an AC voltage and use this AC voltage as a fundamental characteristic for their operation. Because we now have to start with 12 V DC, we have to generate the AC voltage ourselves. We also have to keep in mind that we’re dealing with battery-powered equipment and have to be frugal with energy. The circuit that we finally arrived at can easily drive 6 lamps of 10 W each. Fewer are also possible, of course.
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R1 = 1M
R2 = 47k
R3 = 470k
R4 = 12k
R5 = 100
P1 = 1M preset
C1,C3,C5 = 10nF
C2,C4 = 6nF8
C6 = 100µF 25V radial
D1,D2 = 1N4148
D3 = zener diode 15V /1.3W
T1 = IRL2203, BUZ10, BUZ11, BUZ100 or BUK455 *
IC1 = TS556CN (CMOS) or NE556N (not CMOS)
L1 = 3µH 9A suppressor coil * (e.g., Farnell # 976-416)
K1 = 2-way PCB terminal block, lead pitch 5mm
S1 = on/off switch, 10A
PCB, ref. 030141-1
* see text
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