This Schmitt optical trigger with LDR was found in old documentation. The relay must be sensitive, or an additional step must be used to trigger it.
This 5.1 MHz circuit was found in a 1980s documentation. The frequency is given by the crystal and...
To power small projects, we found this circuit in the Radio Electronics magazine of May 1977. The...
May 2017 - Mouser Electronics already has in stock with the new ADP244x switched regulators from...