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.
Why don't you use a transponder setup for radio control car/boat/airplane racing? Here's one that is used for rc cars;
Be aware that most photoelectric sensors work by pulsing the LED. They do this to get a higher brightness out of it (example: 50% dutycycle at twice the power). As such if you use it to try to measure time there will be a certain "quantizing" error in your measurements. The ones I'm familiar with worked from 60hZ to the hundreds of Hz region. Don't know if thats enough of an error to influence a soapbox derby outcome. (Can a person holding a stopwatch be more accurate than 1/60th of a second?)
THere are of course special analog sensors that are used for time critical measurements but I doubt they would be used on a garage door.
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.
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.