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Quick fix for power issues

Posted: Sun Jun 03, 2018 11:30 pm
by octorian
I just built a mePed kit this weekend. After powering it up, I immediately ran into reliability issues.
After poking around here, it seems as though many of us have run into various forms of brownout issues. Personally, I had a problem where the IR receiver would detect garbage whenever the servos were buzzing. After doing some testing, it seems as though the 5V rail on mine was ~5.1V normally but dropped to ~4.5V when the servos buzzed.

Motors cause noise and voltage dips on power rails. This is a well known issue that many robot projects have to deal with. Some do it with extra filtering, careful distribution, or even multiple power sources (like my ancient WAO II that has two separate battery packs). So I was quite surprised to discover that the mePed does none of these. Anyways, I figured simply adding a capacitor to the 5V rail would help. So I did, by jamming it in the "bluetooth" connector socket, and it worked!


Its a 220uF 10V electrolytic capacitor I found in one of my assortment boxes. Nothing special, but it seems to do the trick.

Re: Quick fix for power issues

Posted: Wed Mar 27, 2019 8:40 pm
by arich
Thanks for posting, this worked!

I had similar issues with the Arduino browning out when I used all motors at once to do a move that lifted the robot up, presumably causing a current spike and a battery voltage drop. I used a 330 uF electrolytic and it is enough to totally eliminate the issue.