- Fri Jan 30, 2009 10:57 am
#64917
you could have a very narrow conductive strip of material, connected to a sensor which reads either voltage or current
each car can have a light, spring loaded sliding contact which gently drags on the ground, connected to a coin cell battery and resistor. each car can have either a different voltage from the coin cell or a different resistor value.
anyways the sensor would read the voltage or current value and instantly know what car has passed.
advantages:
lightweight
simple to implement
battery will last practically forever
if it works, would be very accurate: the thinner you make the path on the ground, the smaller the chances of two cars sending an interfering signal. If you wanted to go further, you could even implement a system where, if a non-expected measurement comes through, a relay is sent to make a high speed digital camera take a picture.
the only possible problem i can foresee is instrument inertia; how fast a reliable reading can be obtained. I think, however, since resolution is not important for a few cars, this is a minor problem and can be solved with any typical high speed a/d converter on a microcontroller
anyways just a thought
each car can have a light, spring loaded sliding contact which gently drags on the ground, connected to a coin cell battery and resistor. each car can have either a different voltage from the coin cell or a different resistor value.
anyways the sensor would read the voltage or current value and instantly know what car has passed.
advantages:
lightweight
simple to implement
battery will last practically forever
if it works, would be very accurate: the thinner you make the path on the ground, the smaller the chances of two cars sending an interfering signal. If you wanted to go further, you could even implement a system where, if a non-expected measurement comes through, a relay is sent to make a high speed digital camera take a picture.
the only possible problem i can foresee is instrument inertia; how fast a reliable reading can be obtained. I think, however, since resolution is not important for a few cars, this is a minor problem and can be solved with any typical high speed a/d converter on a microcontroller
anyways just a thought