This circuit was found in an American documentation from the 1980s. The sensitivity ranges from 100 mV to 1 V. The supply must be done with an excellent filtering source.
This amplifier was found in a Japanese publication in 1972. Transistors are uncommon today, and...
The current of this source is 200 mA at the most, and the output depends on the zener that may...
Found in Mallory documentation from 1968 this circuit uses an integrated circuit from that time. The...