Using the 2N2646 this circuit was found in a Radio Electronics magazine from July 1968. The transistors are from the time and the lamp can be replaced by a high-power LED in a current version.
Found in an EDN from the 90's this circuit makes use of unusual components today. | Clique na...
This circuit consists in a full-wave bridge rectifier or Graetz Bridge as its is also called. The...
The circuit shown in the figure can generate signals of good intensity up to a frequency of 30...