Intermittent buzzer (CB20494E)

This two-tone buzzer can be powered by a solar panel. The circuit is from a 1991 documentation. The transistor is a general-purpose type.

SCA Decoder (CB6199E)
This Radio Electronics circuit, in an 80's edition, decodes the 67 kHz signal used at the time to...
Voltage and Current Regulator (CB5876E)
We find this circuit in a manual of the 80's own used components. The circuit provides an...
Microphone Preamplifie (CB1404E)
This circuit is from an old publication of the 70's. It can be implemented with modern transistors like the...