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Do you think I will need to filter the signal going into the motor controller?
It expects an analog input, and the PWM may be too noisy.
Can I add a capacitor and resistor to make a low-pass filter, and solve that problem?
Quote from: Daanii on November 18, 2010, 11:26:58 PMDo you think I will need to filter the signal going into the motor controller? Hard to say. Have you got any data on the motor controller?
Quote from: Daanii on November 18, 2010, 11:26:58 PMIt expects an analog input, and the PWM may be too noisy. You'd have to test it to make sure.
Quote from: Daanii on November 18, 2010, 11:26:58 PMCan I add a capacitor and resistor to make a low-pass filter, and solve that problem?Maybe...What frequency is the PWM signal?If it isn't decided yet - higher is better when you want to integrate it with a simple RC filter.
It has to be a low resistance (and hence a larger capacity than otherwise), as you still need the current into the controller... Or do you? Sounds a bit odd that an input should need 50mA - did you verify it? If so, what causes it?
The wiring diagram here [Snip] But it's not too helpful.
I'll wire up what you gave me and test it next week over our Thanksgiving holiday here.
The signal comes from an Arduino. It's hard to tell what the frequency is for the Arduino's PWM. But I'm guessing a cutoff frequency of about 1 kHz would work well.
A technical support person at Alltrax told me that the signal to Tab 2 needs 50 milliamps to work properly. I'm not sure why -- he did not say.
The reason I plan to use +5V is because I have that source available from the Arduino. A +12V source will be harder to come by.
How do you feel about the D/A-C solution?
That solution sounds interesting. As you say, it might work better. Do you have a circuit to suggest?
UPDATE:Was this something like what you had in mind? http://www.avrfreaks.net/modules/FreaksFiles/files/424/DN_033.pdf
How many bits of resolution (or number of steps from zero to full speed) do you need?
One more piece of information. Someone asked Alltrax for more information about what is inside their controller. They found a problem. http://lithiumate.elithion.com/php/alltrax.php It looks like a digital potentiometer is the best bet.