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.

6 V power supply with power zener (CB21531E)
This circuit provides 6.3V of output from a 9V input. The circuit was found in a Dutch publication from...
CP2615 USB Interface IC
August 2017 - Mouser Electronics already has in stock the new integrated circuit CP2615, which...
Adder (CB15670E)
The output voltage of this circuit is equal to the sum of the input voltages, if the result is...