Game Show Timer

Here is a really simple game show timer designed with the beginner in

mind! The power source is an ordinary 12 volt lantern battery or battery

pack made up of C or D cells. The lamps may be ordinary flashlight bulbs;

the prototype uses 750 mA Krypton types (KPR112) with wires soldered

directly onto the bulbs. The control devices may be just about any nonsensitive

gate SCRs or triacs with a current rating of a few amps. SCRs are

shown and triacs may be substituted by connecting MT1 to the negative

battery terminal and MT2 to the lamps. In fact, the two types of devices

could probably be mixed if that is what the junk box has to offer! The

zener is an ordinary 9 volt, 1 watt type like the 1N4739. The 100 ohm resistor

may be any type with a rating of 1/8 watt or more. The reset/power

button is an ordinary toggle switch and the pushbuttons are any

convenient normally-open type.

The entire circuit may be built into one box with two wires running out to

each contestant's pushbutton switch or the SCR, lamp, and switch may be

in a remote box for each contestant with three wires running back to the

base unit. Many more than three contestants may be added by repeating

the pattern.