With only 1% distortion, this Motorola amplifier found in a 1968 documentation makes use of period components. The frequency response ranges from 10 Hz to 100 kHz.
Found in Popular Electronics this circuit will trigger a buzzer if the ignition key is removed...
This circuit is from an English publication from 1973, but can be easily assembled today. 2N718 can...
The figure shows how to connect a relay to obtain the latch effect. The circuit is from an...