Electronic timer for speed measurements - has 1 khz oscillator and capacitor:discharge firing with solid:state display

摘要

The electronic timer consists of a display with light-emitting diodes and 4-digit seven-segment display for indicating times up to 9,999 seconds. The device is battery-powered with a rechargeable nickel-cadmium cell giving around 5 volts output. A slide-switch switches the circuit on and if the two external circuits, connected via cable to the two outlet sockets, are connected both green diodes are illuminated. A 1 kHz oscillator runs but the display is frozen until the push-button switch is operated to fire the circuit and start the timing cycle. When the operate button is pressed a capacitor circuit discharges into the external load circuit e.g. detonator etc. By operating a second switch, for example, a foot switch connected to the timer byc able, triggers the firing of the second external device. At the same time, the counter is stopped and the interval time between operation of the first and second switch is displayed.