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Topic: outputting 0-12V variable with Arduino PWM  out. (Read 1 time) previous topic - next topic

mlehmann

Hi,

I'm using an Arduino to control a dimmer. The dimmer needs an analog out 0-12v. I'm using the following circuit to get 12v instead of 5v:

http://itp.nyu.edu/physcomp/Tutorials/HighCurrentLoads

Basically, this is just a TIP120 connected to the PWM out and to the 12v out. The problem is that instead of getting 0-12v with PWM from 0 to 255, I'm getting 6v-12v.

Hope I'm clear enough in my explainations. Any solution or cue to help me fix that? Or any other suggestions to get 0-12v from 0-5v?



retrolefty

Link to the site not loading, will check later if I remember  :)

Lefty

Grumpy_Mike

#2
Feb 12, 2009, 09:57 pm Last Edit: Feb 12, 2009, 10:05 pm by Grumpy_Mike Reason: 1
What are you using as a load?
In that link it was a motor.
You should replace the motor with a 470R resistor and connect your dimmer through a resistor to a capacitor down to ground. Then connect that to the dimmer.

By the way does any one else not seem to be able to see the schematics on this web site, I'm using Fire Fox and they never show up.

Quote
I'm getting 6v-12v.

How are you measuring this?
You won't get an accurate reading on a voltmeter as it is PWM.

mlehmann

#3
Feb 12, 2009, 10:37 pm Last Edit: Feb 12, 2009, 10:41 pm by mlehmann Reason: 1
Thanks, it seems much better now with the resistor and the condenser. Also, I know the dimmer doesn't like PWM. In my older circuit (the one who gave me 5v) I used a condenser to regulate the PWM. This is a real newbie question but I figure the condenser I'm using now will act the same?

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