This power source was found in a 1969’ Electronics World. The version is too sophisticated by the current it supplies and can be implemented with modern transistors.
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....