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copied from the cool tools sticky thread (page 2):


as some of us are up to building computer based a lap timer here is a part list and some tipps.

here are the parts that you would need for a timing system:

- 2 pcs. IR emitter SFH485 - Digi-Key Part Number 475-1469-ND
- 2 pcs. resistor 30 ohm 1W Digi-Key Part Number BC30W-1CT-ND
- 2 pcs. IR receiver SFH 309 FA - Digi-Key Part Number 475-1440-ND

- 1 power supply (wall wart) with something around 5V and 200mA
you can use an artin wallwart as well. if you use a 7.5V@800mA artin wall wart it would be better to use this resistor 1W 47 ohm digikey part number PPC47W-1CT-ND

- 1 parallel port printer cable (to connect the receivers)

i would place the emitters under the track and the receivers above the track in a bridge or something like that. be sure to align the emitters and receivers really well, otherwise it will not work.
the maximum distance between emitters and receivers is something around 2" to 3" (depending on powersupply)

If you can measure the current to the emitters, it should be between 70 and 100mA to each emitter. 100mA is the max.rating for the emitters!

here is a wiring diagramm, done by Gregory Braun, for Laptimer2000.


and here is the wiring of the emitters:


this is how it looks on the track: active lightbridge

The hardware should work for all kinds of race software, i prefer laptimer2000, but it should work with UltimateRacer3.0 as well, even with SlotmanLight (but this is a german only programm).

did i miss anything?

Peter