View Full Version : motor dyno

01-29-2006, 02:25 PM
I'm thinking of a project that can read motor amps, and rpms. These values would be shown on the de-bug screen.
ˇIf anyone has any idea's that can send me in the right direction, or if there is a project already illistrating this I'd apriciate it..... At the moment I'm at a lost.... One possibility might be to use infared to read total rotations..... Not shure if that will work though......ˇ

Jon Williams
01-29-2006, 02:46 PM
Here's an RPM display for a mill -- might get you started: http://www.parallax.com/html_pages/robotics/machining/RPM_display.asp

Jon Williams
Applications Engineer, Parallax

01-29-2006, 02:55 PM
To measure amps, you can hook up a low ohm resistor in series with the motor, and measure the voltage change on that resistor. There should be a relationship between the resistor's voltage and the motor's current draw. Or, you could consider utilizing a multimeter that's read by the stamp (or used as a separate unit itself). You may have to design your own circuit to do this, since most multimeters have a slow refresh rate, and most can't handle too much current (mine is 10 amp max).

01-29-2006, 03:25 PM
I like the mill project. It defff points me in the right direction. I wonder how I can use the hall effect sensor with a small dc motor. The motor can itself has two strong magnets. Idealy it would measure the magnetic field created by the armature core. I'm not sure if that's possible. I guess another idea might be to attach a small magnet to the end of the srmature,(where the pinnion attaches). This may work as long as the weight of the magnet does not take away from the motors effecientsy.... (spelled wrong).
ˇThanks for the great idea's, you have both sent me in the right direction.


01-29-2006, 11:20 PM

Check out Allegro's line of Hall effect current sensors. Nice, cheap and easy to use with the Stamp.


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