This circuit was found in the August 1997 Electronics Now magazine. The circuit uses well-known operational codes and generates signals up to 20 kHz.
The simple optical intercom we show is from a 1995 documentation. The LEDs can be infrared or...
With this circuit it is possible to monitor a signal that is being recorded on an old tape...
An oscillator that can be frequency controlled by a resistive sensor is shown in the figure. The...