This circuit was obtained from an Electronics Now from the 90's. It generates the dial signal and the ring tone, serving for testing as well as for demonstrations.
This circuit is from old documentation but uses components still common in our market. The circuit...
August 2016 - It can be obtained from Mouser Electronics the battery protectors series bq7790x of...
This interesting touch dimmer was obtained in a 1993 publication, basically consisting of a...