This simple circuit to monitor the frequency of the power grid uses an analog indicator. The adjustment trimpot can be 4k7 and the indicator is 100 mA full scale.
This doorbell or buzzer as announced in a 1990s US publication uses an operational amplifier that admits...
This circuit is powered by only 3 V and can flash white LEDs from 3.2 to 3.6 V, as it includes a voltage...
The load on this amplifier is 8-ohm. We found the circuit in a 1972 Motorola amplifier manual. The...