This non-inverting comparator was found in old American documentation. Formulas next to the diagram allow you to calculate the components for the desired performance.
We found this circuit in a 1977 Radio Shack manual. The light bands are given by the operating gain...
This sound meter or sonometer was found in a Popular Electronics from the 80's. The circuit can be...
This circuit is from a 2004 documentation, and can also be used to signal garages with the use of a...