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 JFET amplifier was found in documentation from 1958. The circuit has voltage gain of 4 and 10...
This circuit was found in a 1969 Mullard documentation. Used transistors can be replaced with...
In the figure we have a high input impedance stage with a general purpose PNP transistor. An NPN transistor...