We found this code key or coded keyboard in a publication from the 90s. The circuit uses components that are still common today and is powered by a 12 V voltage according to the relay used.
A touch or the simple approach of the sensor (metal plate) causes this circuit to emit a sound...
The circuit shown in the figure produces pulses of high intensity light at a frequency that...
This circuit was found in an English publication from 1976. It generates sequential signals in the...