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A little about me and the scope of a project like this

A project log for Mebo Robot Mod with Rasp Pi 4 and Adeept Motor Hat

In this Episode, we rip out the original controller board and replace it with a Raspberry Pi 4 and a motor driver board

shawn-alfaroShawn Alfaro 04/19/2022 at 05:100 Comments

A little about me:

I am a life long tinkerer. Growing up I have taken apart more things than I had fixed them. But it wasn't until the last 5 years, did I actually learn anything from my tear downs. I started out really getting into actually fixing things after tinkering with it when I got a 3D Printer 4 years ago. I learned how to upgrade my printers and now I just want the printer to work out of the box with minor upgrades. Im done tinkering with them. Now that I can competently design and print the parts i need for other projects, I learned that spending the money on good machines beats fooling around and tinkering with them instead of printing with them.  

I also apparently have ADHD, and that makes being a tinkerer kind of a pain in the ass. I have LOTS of neato projects, but i don't have a lot of FINISHED projects. Also, I do not document much of anything. Its all up in my head and most of the time it's like a friggin Etch-A-Sketch. I get started, get distracted, and the slate is cleared. The project gets shelved, never to be completed. I decided to try to mitigate this idiotic process and start actually documenting what I'm doing. So that when I die, my wife has an idea of what I was doing so they can give it to my son and my son will have some kind of idea of how to finish it, if he so desires. 

My first step to feeling like I am actually doing something instead of screwing around, is documenting it. Because as you all know, Adam Savage has stated that: "the only difference between Science and screwing around is writing it down."

So im writing it down. I'm done screwing around. (i repeat myself, its a thing)

Where I get my toys:

My friend Rich likes to go to the flea market, thrift stores and yard sales to buy interesting toys and machines for cheap. He brings me all the special pretties and i see what i can do with them. I have 3 Robosapiens, 2 Roboraptors, several toy RC cars, various animal robots etc. Usually all the RC stuff is missing the remote and if i cannot find a replacement, its pretty much open season for me to tear them apart. 

The more recent finds have had internal LiPo batteries, sometimes USB charging, and even app support, like this bot. These are usually more than the usual DC motors and crappy controls of cheaper toys. These more expensive ones  have potentiometers, rotary encoders, photo interrupters etc inside, in addition to the aforementioned LiPo batteries and other modern accoutrements. If the original PCB that runs the whole shebang is borked because the kid that owned it before spilled soda on it, at least the parts are still usable. 

So I started to investigate how i could keep these neat but otherwise functionless toys running and have complete control of them. The advent of the Raspberry Pi and all the new hats that came with it, really opened the door for these useless toys. 

I had an epiphany while tearing down a Wowee quadbot! And it was something that i had overlooked and really didn't even give a second glance. And that was because I had no idea what i was looking at. While tearing down this toy, i saw the DC motor and this other component stuck to it. it was a potentiometer. I had just gotten into those Raspberry Pi driven, laser cut plexi, tank kits that had an arm driven by hobby servos, and had recently taken apart one of them that had never worked. Inside was a small DC motor, some gears, a PCB, and a potentiometer. I did some research and then it all made sense. Essentially, when a toy company builds these motorized toys they use common little DC motors, some plastic gears, slap a potentiometer on one end and then shoot all 5 wires down to the PCB where it does all the work. its cheaper than using the hobby servos we all use for various projects nowadays, but they both do the same thing.

It does make reusing these toys difficult if the main board comes in dead because you either want to see if its worth it to try and repair or replace the board or tear it apart completely for parts and toss them into a bin in your workshop, hoping that you will need a small motor or what have you in the future. (we all do it, its ok to admit it.)

Well I had been doing just that for sometime now and I was dangerously close to becoming a hoarder. But now that i knew what i was looking at, and for, I started seeing ways i could turn these toys into something more powerful. And trust me trying to retrofit a rectangular hobby servo into a toy that wasnt designed for it, really sucks. I would rather tear out the original PCB that ran it, take the 2 wires for the motor and the 3 wires for the potentiometer, solder them onto a servo driver board from a hobby servo, run the standard 3 wires to a servo hat for the Raspberry Pi and bobs your uncle! You now have complete control of that motor like you would a regular hobby servo you bought on amazon. 

I hope. 

That is a theory of mine. I am going to test it by sacrificing the servo motors PCB, solder the motor and potentiometer wires from the toy to it and run the wires to the Pi. 

We will see if it works in a few days

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