Transistor gain meter (CB20522E)

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

Simple MW Radio 2 (CB4360E)
Originally this circuit is from an English magazine, but I found it in Argentina's Radio Chassis...
Current limiter (CB25534E)
This circuit was found in the December 1992 Radio Electronis magazine. R2 is an NTC, there is a...
Signal Follower (CB1356E )
If you have a common analog multimeter, you can increase its input resistance in the measurement of...