Found in Philips' 90s documentation, this small source can use modern transistors like the BD135 for TR4 and the BC series for the rest.
This low power audio amplifier was found at 1992s Popular Electronics. Transistors are general...
This circuit is from a 1998 Electronics Now and can be easily assembled since it uses a common...
This circuit was found in a 80’s American documentation. The adjustment trimpot is from 47k to...