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.

Amplifier for 12 V (CB8962E)
This configuration with the LM383 appears elsewhere on this site. The circuit shown was obtained...
Step-up attenuator (CB26096E)
This signal attenuator was suggested by Electronics Now magazine in April 1999. The circuit is...
Gain 100 Amplifier 741 (CB11923E)
The voltage gain of this DC amplifier is 100 times, given by the relationship between R2 and R1....