About the article

A Star for Christmas

A Star for Christmas
This circuit acts as a simple light effects generator. With the LEDs suitably arranged, it will produce the impression of a star and so makes an ideal Christmas ornament or decorative element. As you can see from the board layout, the LEDs have been arranged in the shape of a star.The first LED to light is the centre one. Thenfollow the LEDs in the inner ring (D3-D19), followed by the next ring, and so on, right up to the outer ring (D43-D50). The sequence is then started again. The speed of the light effect depends on the setting of P1.
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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.

Component list
R1 = 2k?2
R2 = 10k?
R3 = 33k?
R4 = 390?
R5,R6,R9,R12,R15,R18,R21 = 1k?
R7,R8,R10,R11,R13,R14,R16,R17,R19,R20,R22,R23 = 100?
P1 = 25 k? preset
C1,C3,C4 = 100nF
C2 = 2µF2 16V radial
D1 = 1N4148
D2-D50 = LED, red
T1-T7 = BC547
IC1 = 555
IC2 = 4017
9V battery with clip-on connector
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