This circuit was obtained from an American 1980s documentation. The frequency depends on the crystal and the circuit may be a PNP that reaches the generated frequency.
This circuit makes use of an unusual Analog Devices component today. The circuit is from a 90's...
A flash of light on one sensor or the touch of your fingers on the other type of sensor will turn...
This receiver for the mid-wave band was found in a documentation from the 60's. The transistors are made...