Using IR for lap counting/timing

[UglyBagofWater]

First, love the new forum!

Second, in developing a plug-n-race solution for lane chipping, I'm wondering if placing a transmitting IR LED alongside the receiving sensor (assuming the receiving is in the track) would allow an analog car passing over (perhaps with reflective tape beneath the chassis) to trigger the CU. Anyone ever attempt that?



I'm toying with the idea of constructing an Arduino solution using hall effect sensors, but certainly magless cars may be an issue as I'm not confident without testing that a motor alone would trip a hall switch. The above may be an alternate solution for me to investigate (or not).

Thanks for any input.

[PetesLightKits]

If you are attempting to come up with an in-track installation solution, there are one-piece IR emitter/detector units available that are "U" shaped to allow the guide flag to pass between the emitter and detector, which would work better with less fussing about. No need to worry about alignment, placement or reflective properties of different coloured car chassis. They work very well for normal race conditions but are not recommended if you want to use options like re-fueling, available in some timing software packages.

Peter

[RichD]

One of our tracks used an emitter/detector that was activated by the car's guide flag, however some cars have guide flags that are transparent to IR, so eventually dead strips were used. I understand that the problem can be overcome by placing a resistor in the detector circuit. Emitter/detector pairs that face up have been used successfully before, you would probably have to stick shiny duct tape to the underside of the cars.