This circuit was found in the September 1971 Radio Electronics magazine. The buzzer can be replaced by a relay according to the supply voltage. R1 adjusts the sensitivity.
a This circuit was obtained from a 1978 Practical Wireless. It causes a low-power 1.5V lamp to...
This game consists of a variation of the Nerve-Test with the difference that errors are indicated...
This Power supply is intended to Power small loads with currents up to 30 mA. The voltage depends...