Latching relay (CB25722E)

The figure shows how to connect a relay to obtain the latch effect. The circuit is from an Electronics Now from June 1994.

Zero crossing switch (CB6852E)
Found in Motorola documentation from the 90s, this circuit makes use of a triac from that time. The...
Signal injector (CB22526E)
This transistorized signal injector was one of the first that we found using the well-known...
Mini amplifier 2N301 (CB20529E)
This 200-mW amplifier uses one of the first commercial power transistors. The circuit is from a...