Using only one integrated circuit this control was found in an 80's Electronic Engineering. The circuit has the drive's logic information and must be powered by an isolated power source.
PIC18F “K40” Features Intelligent ADC with Filtering and Signal Analysis Capabilities Ideal for...
Found in an English documentation from the 90's, this circuit makes slow logical pulses audible,...
A high-frequency square wave oscillator using an LC-tuned circuit is shown here. The upper...