In Reply to: Re: Car counter posted by Vorel on 05/30/00 at 10:54 AM:
The cars are moving at speeds up to 100Mph. There can be 10 cars crossing the imaginary line at the same time.
AMB makes transponder systems for the R/C car market, and they are $3,000. This is fine for big clubs, but with less than 30 members in our club, we can't afford it.
AMB's system uses a square wave pulsed to a coil to generate a magnetic field. The field is detected with a loop antenna, and I assume bandpass filters (one for each frequency).
I want to build something for our club to do the same thing.