Dimmable Outdoor Lighting

Customizable brightness settings for 12-V LED lamps

Labs Project

Based on a Labs project | January 2015 | Find it here

One bright day last summer our reader Andreas Meyer installed a patio lighting system, using four 3-watt LED spots. The result was far too harsh and bright, however. As nobody expects to wear sunglasses when sitting out on the patio on warm summer evenings, the new lights saw little use. What he needed was a dimming device that would reduce the brightness soothingly and provide greater luxury and convenience…

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Materials

Dimmable Outdoor Lighting

PCB PDF

PIC firmware, source code, VBNET application source, installation version

Extra info / Update

* Control of four LED lamps
* Two-stage dimming of low-voltage LED lamps
* Smooth transition between brightness levels
* Dimming level controlled by motion detector

Component list

Component List

Resistors
(5%, 0.25W, 250V)
R1–R4 = 100Ohm
R5,R6,R7 = 10kOhm
R7 to R10 = 56kOhm *

Capacitors
C1,C2 = 1µF, 50 V, foil, 0.2’’ pitch
C3,C4 = 100nF, 50V, foil, 0.2’’ pitch
C5 = 4.7µF, 35V, electrolytic, upright 5x11mm, 2mm pitch

Semiconductors
D1 = 1N4007
T1–T4 = IRLZ34NPBF
IC1 = PIC12F1840-I/P, programmed *
IC2 = LP2950ACZ-5.0
IC3 = HCPL-814-000E, optoisolator

Miscellaneous
5 pcs 2-way screw terminal block, PCB mount, 0.2’’ pitch
1 pc 2-way screw terminal block, PCB mount, 0.3’’ pitch
2 pcs 6-pin pinheader, SIL, 0.1’’ pitch
Fuseholder, PCB mount, e.g. Schurter 0031.8201
Fuse 1A, 20 x 5 mm *
Pushbutton, PCB mount, make contact, 6 x 6 mm
PCB 140574-1 V2.2 *
8-way IC socket, DIP, for IC1
* see text