Modulated light receiver (CB21790E)

We found this circuit in a Mullard manual from 1960. The transistor is a phototransistor of the time. The gain is 3 dB.

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...