This 4-transistor amplifier can work from 4.5 or 6 V power supplies. We found it in a Mullard transistors manual from 1960. The transistors are from the time.
This traditional flasher configuration with two transistors drives 5 LEDs with a supply that must...
To operate with high input voltages using a 3-terminal voltage regulator such as the LM340-15, we...
This is the circuit of the commercial Japanese megaphone of the 60s model DM-218. The circuit uses...