How is the relay active and passive?
The relay is a switch that opens and closes with an electromagnetic field, or a solid-state switch controlled by an optocoupler. It is a passive component and only a passive source is something else! For example, a diode, a transistor
Simply said: active is added voltage, people feel the feeling of Ma hand.
Passive is no voltage, this is usually done with the signal, of course, people do not feel the feeling of Ma hand.
