This 6-transistor radio was sold in Japan in the 1960s. The super-heterodyne circuit for the OM band was powered by ordinary batteries.
This configuration can be found in other articles on this site. This was obtained in 1998...
In the figure we show how to polarize a phototransistor to obtain sensitivity. The circuit is from...
This compact power supply can be used on the workbench for up to 1 A load. The transformer has 1 A secondary...