This “people detector” with pyroelectric sensor was found in the April 1991 issue of Radio Electronics magazine. The circuit is based on an LM324 and a sensor from that time.
Originally designed to analyze the shape of light pulses from a flash for photographic...
This RCA circuit has current limitation. The circuit is from an ancient American documentation making...
This useful power supply was found in an 1985 Italian publication, but can still be assembled...