Low battery indicator 555 (CB9551E)

This circuit can operate with different voltages, depending on the zener used. We found it in a 90s American documentation.

Digital Voltmeter (CB18145E)
To use the instrument for AC measurement, the tips are A and B. For CC use tips A or B for...
CMOS Amplifier +1 and -1 Gain (CB15751E)
The interesting circuit shown in the figure, can have its gain digitally controlled and present two...
Three Transistors MW Radio (CB12261E)
This simple MW radio was found in a 1975 publication, but it can be mounted with BC548...