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 OP3

Inductive
Relay
Output


Relay Unit....

A relay can be thought of as an electromechanically operated switch. It uses a primary coil of wire to generate a magnetic field, which makes and breaks the contacts of a switch within the relay.

In the circuit shown on the right, the relay controls a Double Pole Double Throw switch (DPDT). This allows two different circuits to be controlled independently. The 33 ohm resistor is used to reduce the primary control voltage down to 6 volts and the diode to prevent dangerous back emf from reaching the previous process module (see OP2).

Higher powered secondary circuits up to 5 amp and 24 volts can be controlled with this particular relay.

 


 

Motor Reversing....

In the circuit on the left, the output of the relay has been connected so it can reverse, or flip the polarity of the voltage going to a motor. When the relay coil receives a sinking input primary voltage, it switches the secondary electrical contacts, causing the + and - connections to the motor to swap over. This causes the motor to change its direction of rotation. The inductive (back e.m.f.) effects are again quite strong and the diode is used to remove them.