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.

10-minute timer 555 (CB9368E)
Found in a magazine 73 for radio amateurs, this circuit has two settings, one for the interval and the...
1 W Amplifier (CB18192E)
This good quality amplifier found in a 1982 documentation has a traditional complementary output...
Frequency Divider With Unijunction Transistors (CB929E)
A low frequency divider can be made using common unijunction transistors as shown by the figure...