This circuit provides a 5 V negative voltage from a positive input voltage. Found in old American documentation, information on the used integrated circuit was not provided. Probably an oscillator.
The circuit presented is from a 2006 documentation. It can turn a set of lamps on or off when...
This second-order filter was found in a 1978 publication and can use common operational amplifiers like...
This simple tone control using two transistors was found in an Electronics Today International of the 90s....