About the article

Dimmer with a Micro

For incandescent and halogen lamps up to 300 watts

Dimmer with a Micro

Dimmers come in many varieties — you’d think. Still, the author did not find what he wanted. So it was back to the drawing board to design a dimmer circuit with the exact personal requirements. The result is a project that’s easy to add to the existing electrical installation as well as simple to operated using existing light switches. The design is for 230 V, 50 Hz AC power lines and our US and Canadian readers are expressly invited to rework it to 110/115 VAC, 60 Hz.

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Gerber file

CAM/CAD data for the PCB referred to in this article is available as a Gerber file. Elektor GREEN and GOLD members can exclusively download these files for free as part of their membership. Gerber files allow a PCB to be produced on an appropriate device available locally, or through an online PCB manufacturing service.

Elektor recommends its business partner Eurocircuits as the company of choice for its own prototypes and volume production in selected cases.

Extra info, Update


- Dimmer function using phase angle control
- Simple to set (can also be permanently set)
- Suitable for two-way switch circuits (staircase circuit)
- very low profile construction (20 mm)
- transformerless

Component list


R1,R2 = 470? 1W

R3, R13 = 15k?

R4 = 10k?

R5 = 1k?

R6,R8 = 15k? 1W

R7 = 220k?

R9,R10 = 820?

R11,R12 = 470?


C1,C2 = 220nF 250V, polypropylene, X2 class

C3,C4 = 220µF 35V, radial, lead pitch 3.5mm

C5,C6,C7 = 100nF, ceramic, lead pitch 5mm


B1 = W06M, bridge rectifier, 1.5A, 600Vpiv, (e.g. Farnell # 1621776)

D1 = 16V 0.5W zener diode

D2,D3 = 6.2V 0.5W zener diode

D4 = LED, low-current, green, 3mm

IC1 = 78L05 (TO-92 case)

IC2 = PIC12F629A (Microchip), DIL8 case, programmed, Elektor Shop # 090315-41

IC3 = SFH620A-3 optocoupler (e.g. Farnell # 1469594)

IC4,IC5 = MOC3022 optocoupler (e.g. Farnell # 1021366)

TRI1 = BTA08-600BRG, triac, 8A, 600V, TO-220AB case (e.g. Farnell # 1057269)


F1 = 1.6 A (slow blow) subminiature, (e.g. DigiKey # 507-1178-ND)

K1 = AK110/6wp, 6-way terminal block, lead pitch 7.5mm

K2 = 3-pin SIL header lead pitch 2.54mm, with jumper

L1 = 2.2mH suppressor coil, (e.g. DigiKey # M8383-ND or Conrad Electronics # 534358-89)

2 pcs DIL6 IC socket

PCB # 090315-1

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