Transistor gain meter (CB20522E)

This circuit was found in a publication in the 1950s, mainly applying to germanium transistors of the time.

Voltage to Frequency Converter with Potentiometer (CB25385E)
We found this circuit in the June 1991 issue of Radio Electronics magazine. The circuit can be...
Transistor Test (CB12379E)
This simple test for general purpose NPN and PNP transistors was found in a 1974 publication....
Battery Step Up Switched Regulator (CB6065E)
This is a circuit suggested by Linear Technology in a 1980s documentation. The integrated circuit is from...