Found in a 1980s telecommunications documentation, the circuit presented acts as a product detector. The modulator or mixer in the square may be that of the previous circuit.
This circuit generates a pulse of duration determined by the capacitor when an object interrupts the...
This “people detector” with pyroelectric sensor was found in the April 1991 issue of Radio...
This wideband circuit with the 4046 PLL was found in the December 1989 Radio Electronics magazine. The...