Preamplifier stage (CB8934E)

This circuit is from a 90s Popular Electronics. It appears elsewhere on this site. Q1 can be any general purpose transistor.

Class A power amplifier (CB22236E)
This circuit is from an American publication from the 60's. The power is on the order of 600 mW....
LED Driver MC34071 (CB15285E)
Other operational amplifiers series, such as the MC34072, MC34074, MC35071, MC35072, MC35074 d...
Device On indicator (CB7014E)
Found in a European magazine from the 90s, this circuit emits beeps that are several seconds apart to...