Transistor gain meter (CB20522E)

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

4mA at 20 mA Generator XTR115 and PGA309 (CB15571E)
The presented circuit is suggested by Texas Instruments (www.ti.com) in its Application Report...
Pressure Transmitter (CB18764E)
This circuit with an industrial standard 4-20 mA interface uses a KPZ20G pressure sensor but can...
Simple 1-transistor oscillator (CB23615E)
This circuit takes advantage of the inductance of the coil of a high-impedance phone to form the...