This audio-driven relay was published in the July 1977 issue of Radio Electronics magazine. The circuit uses CMOS components, and the relay must be a sensitive type.
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...