Author Topic: Tutorial 3: Relay  (Read 153 times)

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Offline Gonzo_Descente

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Tutorial 3: Relay
« on: April 22, 2019, 12:59:34 PM »
A question was asked about relays.  The purpose of a relay is to allow a small signal to control a larger power.  See the circuit in Figure 2.

When 12 Volts is applied to the coil (which is an electromagnet), the switch part moves from the Normally Closed (NC) connection to
the Normally Open (NO) connection. This avoids using only a switch to control a large current or large voltage, and eliminates having
to us a long and heavy set of wires.  When the 12 volts is removed, the relay returns to the un-energized state.

Relays are usually specified in the following manner:  12V-30A.  This means that the coil is energized by 12 Volts DC and can handle
a current through the switch contacts of 30 Amps. This one shown is a single pole (only one circuit).

Many kinds of relays exist, such as the solenoid that connects to your starter.  Really high power relays are called contactors.
« Last Edit: April 22, 2019, 01:02:55 PM by Gonzo_Descente »

Offline Bowie Kid

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Re: Tutorial 3: Relay
« Reply #1 on: April 22, 2019, 06:47:00 PM »
Pretty good start!