The operational amplifier used is not common today, but the circuit can be implemented with modern operational ones. The gain is 1000 and the source must be symmetrical.
This circuit is from the 1968 ARLL documentation. The MOSFET admits equivalent and the coil...
Schmitt Triggers convert a signal of any waveshape in square signals or pulses. The circuit shown...
I found this circuit in a Popular Electronics from November 1993. It allows to use a 12 V x 1 A...