We found this circuit in a documentation from the 90's. The coil has its characteristics given next to the diagram. Power is provided by a 9 V battery and a range of a few tens of meters.
In the circuit that uses a PIC16F84, the audio present at the input will have its level controlled by...
August 2017 - STMicroelectronics' new T850 switches with triacs up to 8 A can be obtained from...
This circuit was found in an American documentation from 1969. The circuit is a multi-indicator with...