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.
This is the application note circuit of the integrated circuit used with the LASER diode. The...
Suggested by a 1990 book for amateurs, this circuit makes use of an integrated component that is...
Found in Popular Electronics from the 90s, this circuit generates two tones that are selected by a...