Audio amplifier 741 (CB20478E)

This low power audio amplifier was found at 1992s Popular Electronics. Transistors are general purpose common types.

TTL interface with optical coupler (CB25492E)
The figure shows how to couple two TTL circuits using an optical coupler to obtain isolation. The...
Dimmer with SCR (CB23809E)
This old dimmer with SCR appeared in Radio Electronics magazine in February 1962. SCRs were just...
Emitter Follower (CB6155E)
This circuit was found in a 1967 US documentation. The circuit applies to modern general purpose...