This circuit uses an unusual sensor nowadays, but the configuration can be adapted to more modern types, as well as the operational amplifier. The circuit is from an 80's documentation.
We found this simple circuit with headphones listening in Radio Electronics magazine from March...
This circuit was obtained from Maxim documentation. The circuit has 4.5 and 5.5V thresholds for...
This complementary-output amplifier can be used to source a good qualuty signal to high impedance...