Is is possible to modulate voltage

[mikey00409]

I am doing a project for school to control a DC motor using an Arduino Uno card. I want to know if it is possible to modulate the voltage output on any of the pins. What I would like to try to do is connect a dial input from the front panel that would allow me to increase and decrease the voltage to the motor. When testing the Arduino card I found that I get 5 volts out however my motor is rated at 1.5-3 volts. So I would like to be able to reduce the amount of voltage and be able to adjust it from the front panel. Can anyone help me do this?

[Albert.Geven]

Hi

The arduino unodoes not have a real voltage output. It uses pulse width modulation to simulate that. Meaning a pulse is on for a shorter or longer time. If you let the coil of your motor intgrate this signal it looks as if a lower voltage/ power is supplied, but better use a H-Bridge extension to amplfy the output of the arduino.

[mikey00409]

That's quite interesting.   Ok at least I know. I actualy need to build a T bridge, that's what my professor wants use to use.  I do t know the difference but I guess that's the. Point of the project is to research it.  So pulse will make the control more interesting.  Ok so how do I use pulse in labview with the Arduino toolkit.  Is there built in sub vis?

[Nathan_B.]

What pulse are you asking about?  The pulse that Albert mentioned is PWM from the analog pins.  You simply use an analog output voltage.

[hrh1818]

In this groups home page click on the tab "Documents".  There you will the example "Basic Motor with PWM (CCW & CW)".  This example does what you are looking for.

hrh1818

[mikey00409]

Ok i think I can try to make sense of that program thanks a bunch.  They are using analog pin, i have an arduino uno and my pwm is on the digital i thought... or am i wrong, are those analog pins 0-13.  the other side of the board shows analog but it says input...im new to the arduino thing and im trying to make sense of how it all functions, so forgive me if these questions are trivial.

[mikey00409]

This is the arduino i have

[hrh1818]

The Analog Write (PWM) function works with digital pins.  See:

<http://arduino.cc/en/Reference/analogWrite#.UxJayuNdU_o>

The example uses pins 4, 5, 6, an d 7.  Look at the right side of the front panel.

I don't know how the author of the example is using the analog pins.

hrh1818

[mikey00409]

I've been playing around with the PWM.   What exactly does the digital write PWM input Duty cycle 0-255 do exactly?  Is that changing the pulse frequency?

[hrh1818]

PWM doesn't change the frequency of the pulse. It instead varies the ratio of on time to the pulse period. Pulse period is the reciprocal of frequency.  For more information look at the graphs at the following web page.

<http://arduino.cc/en/Tutorial/PWM#.UxUPnONdU_o>

hrh1818