This circuit was obtained from Dutch documentation from 1967. It uses transistors of the time which can be the BFY50 and 51 for the output and the BC series for the others.
This circuit was found in an American audio documentation from 1968. The configuration can be...
This converter uses an SG1524 integrated circuit, which is uncommon nowadays. The circuit is from...
This circuit was found on an 80's Ham Radio. The transistor admits equivalent. The circuit can...