Regenerative circuit for two sensors (CB8266E)

Found in a 1967 American publication, this circuit with feedback for two transistors has a gain of 20 times. Phototransistors are types of the time.

| Clique na imagem para ampliar |

Hartley Oscillator (CB19577E)
The frequency of this oscillator depends on T, which for the audio band can be a common output...
3-Range FET Voltmeter (CB25570E)
This circuit can work with almost any JFET. The circuit is from an Electronics Now from April...
Simple VCO (CB8745E)
This voltage-controlled oscillator uses components that are still common in our market. The...