Serial switch with PIN diode (CB21257E)

This circuit was found in a Popular Electronics from the 90's. The circuit is connected in series.

Two Transistor Super heterodyne (CB20574E)
This circuit was found in an English publication from 1967. The circuit is for listening on a...
Digital Multimeter Thermometer (CB17031E)
This circuit allows you to use a digital multimeter as a thermometer. The sensor is mounted in a...
Capacitance meter 555 (CB18927E)
This configuration, which appears in other articles on this website, was found in a European...