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Electronics => Electronics => Topic started by: mstacho on June 14, 2011, 09:09:54 AM

Title: pwm into another pwm motor controller?
Post by: mstacho on June 14, 2011, 09:09:54 AM
We have a black box motor controller that takes a 0-5V analog signal and turns it into (I think) a PWM input to a 48V, 60A motor.  Suffice it to say the motor needs enough power to make it impractical for me to just make my own controller.

We have another system that generates a PWM motor control signal.  So here's the question:  can I just hook the PWM output of this system into the analog input of the black box?  Will that work just like if we had supplied the actual analog voltage?

If not, is there a particularly easy way to turn PWM into an analog voltage?

MIKE
Title: Re: pwm into another pwm motor controller?
Post by: newInRobotics on June 14, 2011, 10:43:59 AM
Hi there.

can I just hook the PWM output of this system into the analog input of the black box?  Will that work just like if we had supplied the actual analog voltage?
No it would not work, it would still be PWM instead of analog voltage.

If not, is there a particularly easy way to turn PWM into an analog voltage?
Yes there is. You need to use resistor in series with PWM output followed by a capacitor (Low Pass filter) (http://en.wikipedia.org/wiki/Low-pass_filter). Use Sabertooth 2x25 User’s Guide (http://www.dimensionengineering.com/datasheets/Sabertooth2x25.pdf), page 11, as a reference.
Title: Re: pwm into another pwm motor controller?
Post by: mstacho on June 14, 2011, 02:41:50 PM
Um...this might get posted twice, sorry if it does:

Awesome, that's just what I needed.  thanks.

MIKE
Title: Re: pwm into another pwm motor controller?
Post by: newInRobotics on June 15, 2011, 09:30:49 AM
No problem at all  :)