Article
Racetrack Timer
for the fast guys
A model racetrack is a nice toy for boys. Even the ‘big’ boys like to race a little every once in a while. Of course, it is no longer considered ‘playing’, but ‘amateur racing’. If you then invite a friend for a match, the emotions can sometimes run high when it comes to deciding who crossed the finish line first. Here we present a circuit that can help you out in such situations.
Materials
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.
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PCB
Component list
Resistors:
R1,R2,R6 = 22k
R3 = 2k2
R4,R5 = 1k
R7 = 18
Capacitors:
C1-C5 = 10µF 25V radial
C6,C7,C8,C11 = 100nF
C9,C10 = 22pF
Semiconductors:
D1,D2 = LED, low current, 3mm
D3,D4 = IR LED, e.g., TSUS5202
D5,D6 = IR PIN photodiode, e.g., BPW41
IC1 = AT89C2051-24PI, programmed, Publishers order code 040395-41
IC2 = MAX232
IC3 = TLC272
Miscellaneous:
K1 = 4-way SIL connector
K2 = 9-way angled sub-D socket, (female), PCB mount
X1 = 12MHz quartz crystal
PCB, ref. 040395-1 from The PCBShop
Project software, Publishers code 040395-81
R1,R2,R6 = 22k
R3 = 2k2
R4,R5 = 1k
R7 = 18
Capacitors:
C1-C5 = 10µF 25V radial
C6,C7,C8,C11 = 100nF
C9,C10 = 22pF
Semiconductors:
D1,D2 = LED, low current, 3mm
D3,D4 = IR LED, e.g., TSUS5202
D5,D6 = IR PIN photodiode, e.g., BPW41
IC1 = AT89C2051-24PI, programmed, Publishers order code 040395-41
IC2 = MAX232
IC3 = TLC272
Miscellaneous:
K1 = 4-way SIL connector
K2 = 9-way angled sub-D socket, (female), PCB mount
X1 = 12MHz quartz crystal
PCB, ref. 040395-1 from The PCBShop
Project software, Publishers code 040395-81
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