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Posted by on November 29, 2006, 10:03 am
Tony Hwang wrote:
> John65stang wrote:
> > What I need to know is how the "electronic eyes" work. Do they send a
> > signal back to the opener ? Are they just a voltage loop that is opened
> > when something crosses the beam ? I believe thay are powered by DC
> > voltage.
> >
> > The reason I ask is I am trying to build a timing clock for a guy and his
> > soap box derby car, and he got a pair of sensors for us to use and timing
> > spots to start and stop the digital stop watch, I need to build.
> >
> Hi,
> Typically it is a IR emitter and sensor set up. If beam is interupted,
> sensor generates signal. From this you can rig up anything you want.
Actually, it's the reverse, at least for the sensor itself. When light
energy hits the receiving sensor, it generates a voltage which is then
detected. If he wants to use what he has,he can use a VOM to measure
it, then rig up an apporpriate circuit. However, I'd check Radio
Shack, as they may have cheap kit or already built hobby type solutions
for this.
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