I've just made this little starting device for Dual lane 'random' starts. I made a bigger version with switchs to determine the second timing, using speakers and a 'beep' tone generator, but felt a simpler,less power hungry and compact version would be nice.
By pressing Red square button on the right gives a one second burst of sound through two Piezo buzzers from a reversing warning system. Cheap ,compact and make a nice/awful beep. The pos and neg outputs are at the top of the device.
The starter then presses the R/H red button and that starts both clocks going and also another 1 second beep , determined by a 555 chip circuit giving a 1 second 'monoshot'. The wires to the timer on/off are poking out the sides.
The device also incorporates a relay, that when triggered by a tapeswitch prevents the l/H buzzer switch operating, and throuws up a flashing red LED indicator to the botton r/h and L/h sides of the box indicating which lane false started first. The central round red button re-sets everything.
The batterys (two 9v) are kept out side the case for easy/fast replacement.
To go with the box I have built tow extra toys....a VERY LOUD klaxon alarm to be sounded if a false start occurs. I alsobuilt a simple electronic die, to randomly generate the time spacing. All the starter needs do is count in their head the time between buzzer 1, and the start.
This is to work with the 'random' start system, where racers only go on the final beep, not before.
it measures 5' x3" approx
