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.
This digital CMOS circuit generates sinusoidal signals from a 10 kHz rectangular signal. The...
Found in an 80's Elektor, this circuit can use any equivalent optical coupler. The buzzer is of the...
Found in a 1965 Electronic Design, this circuit limits surges in a load when power is applied. The...