IA set is 4 poles, two transmitters and two receivers. To start the time, the dog (from Chicuacua to St. Bernard) goes between the poles (a transmitter and a receiver) to start the run and timer and at the end of the run goes between second set (a transmitter and receiver).
Often, the timer is place in front of a jump. Small dogs jump as low as 4” and depending upon the dog’s size the dogs can jump up to 24” with just about every 2” between 4” & 24”. Also, sometimes large dogs jump especially high, such as 30”.
Therefore my design has a beam at 7”, 11”, 15”, 19”, 25”, 30”, & 35” which I’ve calculated should break a beam based upon the size of the dog. The Photon in the design sits at about 22” in the middle so the wires extend from the Pohron 20”, 15”, & 10” in each direction.
National dog trials have prize pools of $10,000 with the placements decided in the 100ths of a second. There currently are timers such as these which sell for $2200 per set. I decided to make a replacement using an iPhone/iPad as the logic and timer and the poles only sending keep-Alives and beam breaks.
I have a model working pretty dependably with three “eyes” (beams). The receiver circuits with resistor, capacitors and receiver are on small circuit boards at the opening in the pole. The wires for power extend from a power booster at the bottom of the pole to the top and the wire carrying that detected signal extends from the eye to the Photon. The wires are twisted to avoid cross-talk. The circuit for the emitter is on a small board with resistors, capacitor, MOSFET, and IR LED. Again, the power wires are as described above and the PWM pins are connected to the remote MOSFET with a control wire from Photon.
The IR LEDs are toggled off and on rapidly so that near LEDs will not effect the receiver. To this end, the LEDs are turned on 1, 4, 2, 5, 3, 6. Currently, I plan on only 6 LEDs for 7 receivers.
I am including a picture of the prototype with 3 eyes, first one of the front and then one with the back open so you can see the wiring