This amplifier, from Philips Databook is suitable for automotive applications. The input resistance is 60k ohms and the frequency range is 20 to 20 kHz.
This variable filter circuit was found in July 1975 Radio Electronics magazine. The circuit uses 3...
This Hughes circuit is from 1968. Equivalent modern components can be used. The input impedance is...
This circuit emits a warning sound when night falls. The circuit is from a Hands On Electronics from...