This variable 1 A power supply with voltages up to 30 V was found in an article in June 1986 Radio Electronics magazine. The 723 IC is well known to magazine readers of the time and even today.
This circuit is from 1968 documentation. We can assemble it with more modern components such as a...
Found in a 90s Silicon Chip documentation this circuit is intended to protect a speaker system in...
The UVTRON tube is an ultraviolet radiation sensor. In this circuit from Radio Electronics from...