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High Power Exclusive OR Gate Help

Circuitz

Dec 7, 2013
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Hey all-

I am trying to learn about/build a circuit to control a 2 amp electric motor. Basically I would like the electric motor to be controlled by 12 volt DC pulse width modulation. However, I would like to apply a small digital positive current 5 volt signal to the gate via my arduino digital outputs to the gate to switch off the high amp current quickly.

From my research this looks like I need an exclusive OR gate (XOR). Most of the integrated circuits that I see from Texas Instruments are only rated to control milliamp circuits. I think I could build my own gate out of very large transistors with heat sinks but it sort of seems like overkill for only 2 amps. Is there an easier way to do what I am trying to do? Thanks!
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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Jan 21, 2010
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You want to control a 12V 2A motor from an arduino?

What you want is a mosfet.

I think we have a resource describing how to use a most to switch a load.
 

Circuitz

Dec 7, 2013
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I don't want to drive it from an arduino as it has a separate drive circuit... I only want to switch it off with the arduino. Is that the same thing? Is there an exclusive OR mosfet?
 

BobK

Jan 5, 2010
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Where did you get the idea that you need an XOR gate?

Bob
 

BobK

Jan 5, 2010
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A MOSFET can easily control a 2A motor, and if you choose a logic level one, it can be controlled directly from an Arduino.

Bob
 

Circuitz

Dec 7, 2013
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Thanks for the replies!

The reason I think I need an XOR gate is because I want to turn OFF the 2A circuit when the arduino applies power. The research I have done on MOSFET arduino control is the opposite in that it turns ON the circuit when power is applied. In my scenario the circuit will be on a lot more than it will be off. You are correct with the 5 V arduino and the 12V motor, I would def need a logic level mosfet, but how do I make it operate normally closed instead of normally open?
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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Jan 21, 2010
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You need to explain further. Do you want the device turned on when there is no power applied to the arduino?

A mosfet requires a voltage to remain turned on, but it doesn't actually consume any power. A different voltage is required for it to be turned off.

This is different from a bipolar transistor which requires current to flow through the device to maintain it in a turned on state.

Please forget XOR. Even if some sort of high power xor existed, xoring a pwm signal with some logic state will invert the duty cycle, not turn the output on and off (afaict an AND gate is what would do what you want, and placing a mosfet in series with the load effectively implements this function)
 

Circuitz

Dec 7, 2013
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Steve,

Thanks!

I did not understand that a mosfet doesn't consume current to remain on. The arduino will be powered on but I did not want it to overheat by applying a constant drain for an extended period just to maintain the on state of the motor circuit. I will look into the mosfet circuit more carefully now- thanks!!
 

AnalogKid

Jun 10, 2015
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I think you misunderstand the term "exclusive" as used in combinatorial logic parts. Of the six basic logic gate configurations, the exclusive-or and exclusive-nor are the only ones that will *not* do what you want. If one input to an XOR or XNOR gate is a pulse train such as a PWM signal, the other input acts as an invert/non-invert control. This is clear from the truth tables. Assuming that you do not want to invert the PWM signal and that the arduino output is positive-true logic, then what you want is an AND gate.

But it really is *impossible to say* without a schematic or block diagram or something from you other than your description (which is not very clear).

ak
 

BobK

Jan 5, 2010
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You could start by telling us what are the two inputs that you want to combine with a gate. And then tell us how you want to output to behave.

There may be high power gates implemented somewhere, but any gate can be made "high power" simply by using it to drive a transistor or MOSFET. This is the way it is normally done.

Bob
 
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