Door buzzer or alarm (CB20492E)

This solar powered circuit was found in a 1991 documentation. The transistor is a general purpose NPN.

FM transmitter (CB16910E)
This FM transmitter has a high power thanks to a push-pull amplifier stage at the output. The coil...
6 V Battery Charger (CB13014E)
The circuit shown in the figure is characterized by the existence of a current limiter based on...
Dual trace for oscilloscope (CB5438E)
This circuit shows on the screen of an oscilloscope two signals alternately at a frequency that depends...