Let's Make Robots!

"The Better Mousetrap" Servo Tester

I've decided that my new servo tester (based on RoboPi) deserved a page of its own on my site, and that other LMR users may be interested in following my build log.

"The Better Mousetrap Servo Tester"

You can find the build log, and more photos at:


(The jitter issue is now identified as the MG-995 servos needing unusually clean servo power)

June 21 2014: I made two "special" servo extension cables so that I can run all of HexPI's 18 servos from TBMST, and I'll be adding an ATX power supply to see if having 20A available for the servos will quiet the jitter. I'll let y'all know how it turns out.

I'd be happy to answer your questions here, and I'd love to get your feedback!




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The Better Mousetrap Servo Tester

I added two small breadboards, one each to the left and right of RoboPi, and moved the breadboard powersupply onto the small breadboard on the right. More at my build log.

TBMST has been working for a while now, but I was not happy with the jitter I was seeing with a Tower Pro MG-995 servo (even after I improved the PWM timing), so today I decided to get to the bottom of it.

More details at http://www.mikronauts.com/the-better-mousetrap-servo-tester/

Adding the electrolytic capacitors to filter the servo voltage helped a lot, but I am still trying to track down why the GWS MT-1 servo tester jitters less than TBMST.

What is strange is that TBMST now provides cleaner power than the MT-1 to the servo, and TBMST's timing is also a lot more precise... so it pretty much has to do with the quality of power or servo control signal strength. I'll get to the bottom of it.

I picked up some larger electrolytic capacitors over the weekend, and as expected, they reduced (but did not eliminate) the jitter from the MG-995 servo I am using for testing TBMST.

So I had an interesting thought... would the GWS MT-1 servo tester still behave better (ie almost no jitter) if it was powered the same way that TBMST was?

The answer is NO! It is the the power supply!

Now I just have to come up with a clean enough power source, and I can resume my HexPi build!

More details at: