Found in documentation from the 90s, this circuit triggers a relay with inductive signals applied to a link. The sensitivity depends on the frequency and the power supply depends on the relay used.
This is the traditional configuration of a differentiator with an operational amplifier. This was...
This amplifier circuit with a low power MOSFET was found in Popular Electronics from the 90s. The...
We found this circuit in Motorola's Circuit Applications for the Triac 1971 manual. The circuit is for ½...