This instrumentation circuit was found in the September 1989 Radio Electronics magazine. The circuit uses an analog indicator and the power supply must be symmetrical.
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...