based on a PIC microcontroller with a few added components, converts a sensor-based voltage into a 4- to 20-mA current loop. Shown is the circuit as originally drawn on a whiteboard. The ADC input ...

Since those were the days before inexpensive microcontrollers ... or as an output. The analog core of the circuit is an operational amplifier integrator (IC2b) whose reference voltage is ...

Back in the day where the microprocessor was our standard building block, we tended to concentrate on computation and processing of data and not so much on I/O. Simply put there were a lot of ...