Inductive
Relay Output
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A relay can be thought of as an electrically/magnetically operated switch. Relays contain a primary coil of wire to generate a magnetic field. This makes and breaks (by magnetism) the contacts of a switch within the relay. This relay has a Double Pole Double Throw (DPDT) switch which allows two different circuits to be switched or controlled independently. Higher powered circuits can be independently controlled with a relay. Circuit Notes:
The 33 ohm resistor
reduces the supply voltage down to 6 volts. |
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The output of this DPDT relay has been connected so it can reverse or flip the voltage going to a motor. When the relay input receives a "sinking" input voltage from the transistor, it operates and switches its electrical contacts. This causes the power connected to the motor (via the relay) to reverse its polarity (ie. the + and - swap round). The motor now changes its direction of rotation. The inductive (back e.m.f.) effects are quite strong and the diode is again used to remove them (see inductive outputs). |