Filament source (T398E)

Despite being transistorized, this is a constant current source circuit for 1 V valve filaments such as the 1H4 tube.

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...