High gain microammeter (CB22305E)

This circuit is from an American transistor book from the 60's. The transistor is germanium of the time.

Balanced Mixer as Product Detector (CB4235E)
Found in a 1980s telecommunications documentation, the circuit presented acts as a product...
RN2903 Transceiver Module for Long Range (COM036E)
It can be obtained from Mouser Electronics new transceiver modules long range (LORA) Microchip...
Automatic Reset Circuit for Infrared Control (CB24832E)
Working with the previous circuits, this circuit resets after 1 second. The circuit is from Radio...