Homing Circuit

erco

I knocked this circuit up as part of a bigger project and am sharing it here in hopes it helps someone someday. It was a fun little side project. All mechanical, but ultimately will be controlled by a micro. One-directional homing circuits are simple and nothing new, but this one "goes both ways." That's as PC as I get. The thumbnail is my hand-scrawled schematic.

erco

Attaching schematic since it gets partially obscured in the Youtube window.

hatallica

Wow, this brings back (mostly good) memories of exploiting the "park" position of a windshield wiper motor.

justanswer.com/uploads/sasso1179/2008-09-01_204230_wiper.gif

erco

Yep, similar to wiper homing. But this circuit differs in that it drives the motor both ways (many wipers oscillate mechanically and the motor rotates in one direction) and this one does dynamic braking to stop the motor quickly and avoid overshoot.

BTW, your GIF won't load, hatallica.

hatallica

Weird ... the GIF shows on my computer.

Dare I ask what the larger project is, that will be utilizing the bi-directional homing scheme? Low idle power, 360-degree/step stepper motor drive?

MikeDYur

@erco, What is the smallest robot that you have created?

I have recently salvaged a pile of small motors used for vibration in generic PS3 controllers. It is about the only thing salvageable from these items, plus I have a handful of really small vibration motors from old cell phones.
Just wondered if you or someone else has found a use for such a thing, they have to be durable to run off balance as they do. I realize you need to be able to remove the weight from the shaft, and refit a gear or something else to it.

Knowing you, maybe you figured out how to use the vibration to an advantage!

MikeY