This source with two symmetrical output voltages was found in 90s Radio Electronics. The 22 V output has a maximum current of 300 mA and the 5 V output has a maximum current of 4 A.
I found this circuit in an old Argentine publication from 1973. The components are no longer...
This circuit has an LED indication of the timing progress, having been found in an old...
This simple signal tracer was found in a Popular Electronics from the 90's. The transistor can be a...