This circuit sounds when the input voltage drops below the value determined by the zener. The circuit is from a 90s American documentation.
September 2017 - Amphenol PcD's Solaris Connector series is available from Mouser Electronics. In...
We found this circuit in a 90s Popular Electronics. The circuit can be implemented with modern...
This physical line servo control uses components that are not currently common. The circuit is from...