What does a relay do?
Senior Member
Joined: Jan 2001
Posts: 677
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From: Denver, CO
It is a remote switch. The reason to use one is to control the on/off operation of a high current device.
Example, horn relay - A small current flows through the contacts of the steering wheel and engage a relay (turn it on, close contacts, etc). Then current can flow to the horn.
The relay only needs a 1/100 of an amp to close. The horn itself may need 10 amps to operate.
Since a 1/100 of an amp is needed to make the relay close, smaller wire and contacts can be used.
Example, horn relay - A small current flows through the contacts of the steering wheel and engage a relay (turn it on, close contacts, etc). Then current can flow to the horn.
The relay only needs a 1/100 of an amp to close. The horn itself may need 10 amps to operate.
Since a 1/100 of an amp is needed to make the relay close, smaller wire and contacts can be used.
Member
Joined: Jul 2000
Posts: 461
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From: Warrenton, VA U.S.A.
There are many reasons to use a relay. Another reason would be to electrically isolate the circuit being switched, although the most common would be to switch a larger amount of current. A good example would be a solenoid which switches hundres of amperes, yet requires only a fraction of an ampere to switch it on/off.
12VDC relays generally draw 100-300mA (0.1 - 0.3 amperes) which equate to ~1/10 ampere (not 1/100, which would be 10mA, or 0.01 ampere).
12VDC relays generally draw 100-300mA (0.1 - 0.3 amperes) which equate to ~1/10 ampere (not 1/100, which would be 10mA, or 0.01 ampere).
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