Found in a 1969 documentation, this circuit for the 20 MHz band does not use a transformer. The circuit is a phase detector that makes use of the transistor of the time.
The presented circuit is suggested by Texas Instruments (www.ti.com) in its Application Report...
This circuit with an industrial standard 4-20 mA interface uses a KPZ20G pressure sensor but can...
This circuit takes advantage of the inductance of the coil of a high-impedance phone to form the...