A relay is, as it were, a remote controlled switch.
In an electronic circuit often needs a switch to be used in areas that are substantially inaccessible, so that it would be impossible to control that.
In that case, a relay can be incorporated in place of a switch.
Further, a relay always applied as between the place is switched and the switching contacts themselves no long connection lines may run on malfunctions.
A relay consists of a group of switching contacts which are operated via a magnetic coil.
This coil is fed with an electrical voltage that can be operated by means of a normal manually operated switch.
This hand-operated switch can be located at a large distance from the switching relay, with a pair of electric wires as the connection.
In the normal case, the relay has only two switching positions the one position if there is, current flows through the coil, and the other position when there is no current flowing through the coil.
Also, when the main relay is playing a role, as a rule, the greater the relay, the more serious the contacts, so he can handle more current.
If high voltages are switched, the contact distance must also increase.
A special position takes the polarized relay.
While a normal relay can be controlled with a switch as a co-DC voltage which is supplied to the magnetic coil, can there in against a polarized relay, can only be controlled with a DC voltage.
Since in indicates the terminal of the battery, on the two connection wires of the magnet coil clearly the position in or out to.
An example: The positive terminal of the battery is connected to wire 1 and the negative pole of the battery is connected to wire 2 of the magnetic coil, the relay is for example in the mode activated, we take apart the battery will then provide a permanent magnet in the Relay sure that once occupied position is maintained.
Re-enable the battery change anything.
However, it is different when we were to swap the lead wires 1 and 2 in place.
Namely the relay switches over and remains engaged position maintained until the poles are changed again.
THE RELAY FOR USE IN PRACTICE:
- The distance to operate a switch.
- With low switching capacities, minor currents or voltages in the magnet coil to be able to switch large currents.
- Switches for use on sensitive fault locations in a circuit.
- With a simple switch via a relay to control a complex group of contacts.
- With one or more relays to build logic circuits, for example, in the digital technique, then the relay performs as a yes / no task.
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