We have many tube tester circuits in this section. This one came out on a Radio Electronics from 1949 and has a very elaborate configuration with toggle switches.
This conventional version with a transistor, already explored many times on our website, was found...
This circuit came out in an English magazine from 1977, but it can be easily assembled today, as...
This simple radio for listening to a headphone with two CK722 transistors was found in Radio...