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Author Topic: High Voltage  (Read 661 times)
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Hi,
Do anyone know how to use arduino to turn on a 120 V fan?

Thanks!
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I'd use a relay.. any old relay, or buy a breakout board with a relay on (comes with optoisolaters/diodes)
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Or use a solid state relay, they are called SSR
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Thank you!
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If it's a DC motor, you can use an SCR (Silicon Controlled Rectifier).
If it's an AC motor, you can use a TRIAC. 

You can also use mechanical relays, or solid state relays, or Mosfets.

Since it's line voltage, might also help to have some physical isolation between your low voltage electronics and the high voltage section (for added safety). You can use "optical" equipped mosfets, etc...  basically, your low voltage electronics turns on a small LED (inside the mosfet), and the light emitted is detected, which then switches/turns on the high voltage side of the Mosfet (everything happening internally).
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Adafruit has this.

Disclaimer... it says something about derating when the load isn't resistive and I think a motor is inductive?
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Roy from ITCrowd: Have you tried turning it off an on again?
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Thanks for the link. That is pretty good pre-packaged solution.

For motors, use 20% of rated... so 15A x .2 = 3Amp max.
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Quote
If it's a DC motor, you can use an SCR (Silicon Controlled Rectifier).

That is not true, a SCR will not control a DC motor as once you trigger the SCR on the only way to turn it off is to remove power from the motor circuit.

Lefty

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Quote
If it's a DC motor, you can use an SCR (Silicon Controlled Rectifier).

That is not true, a SCR will not control a DC motor as once you trigger the SCR on the only way to turn it off is to remove power from the motor circuit.

Lefty



You're right about the SCR. I was just thinking of turning it ON. 

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No... Not Quite... @Lefty What about commutation with an inductive load?  <BFG>

Bob
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