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.

Resistors:
R1 = 2kΩ2
R2 = 10kΩ
R3 = 33kΩ
R4 = 390Ω
R5,R6,R9,R12,R15,R18,R21 = 1kΩ
R7,R8,R10,R11,R13,R14,R16,R17,R19,R20,R22,R23 = 100Ω
P1 = 25 kΩ preset
Capacitors:
C1,C3,C4 = 100nF
C2 = 2µF2 16V radial
Semiconductors:
D1 = 1N4148
D2-D50 = LED, red
T1-T7 = BC547
IC1 = 555
IC2 = 4017
Miscellaneous:
9V battery with clip-on connector