Oldschool to me anyways. Has anyone seen a speed controller like this?


Belongs to a neighbor kid, it was his father's.
Seems like it'd be cool to finish what was started, unfortunately don't have the know-how or the friends.

Now, we've got the car. It was already set up but the electrical was.. pretty much as you see it but unattached to the car or other components.
Looking at that little goofy circuit board it's apparent that it's responsible for receiving power from the battery, sending it to a radio transmitter (which has multiple slots to hook up a servo for controlling steering, and one for moving that rotating part on the speed controller which moves its two contact points around) and also to the motor.

​​​​​​The way it was wired (you can see in the picture) the on/off switch went between this speed controller and the radio transmitter.. that seems odd to me. It also seems strange that there's no way to regulate the amount of power sent through the system from the battery.

My idiot self.. Removed the battery from the kid's recently dead hoverboard thinking the parts would take what they need. Well, we made fire and melted a butt connector but hey, no injuries!!!. That's part of what spurred the thought that something should moderate current, but I suppose it is possible that an appropriate battery would have a low enough output as to. not make fire..

Anyways, any help would be appreciated!! Any knowledge gets passed on to the kid. Even if we wind up switching the electrical over to new tech that is plug and play, we're both curious as to how this works.

EDIT:Oh, if anybody does see this post and maybe wants more pictures, just let me know, I'll go take 'em.
I'd have gone to a hobby shop to ask but with the quarantine in place they aren't open.

 

I think modern speed controllers use pulse width modulation to vary the power to the wheels, the old ones had a few resistors of varying strength, one per contact so the servo sweeps the arm back and forth and completes the circuit with varying levels of output.

This is from back in the six pack NiCd days, so 7.2 volts for the pack. Bet the hoverboard had a lot more than that, but I'm not good enough with electrical stuff to have a feel for whether or not flames should be expected from running (quick google search) 36v through whatever resistor was in the thing.

 

There were no resistors that I recognized, so I assume any resistance was on or in the motor (the tires didn't spin when this jolt hit, so it's likely fried). I wish I wasn't so tired and wound up when I was in the service, got to be a part swapper on tanks (didn't get it when the grown-ups called us that). If I could've taken apart the broken stuff we had it could have saved them quite a bit of money I think, and taught me so much.

So! It looks like new electronics are in order, as well as some reading up on pulse width modulation. I couldn't even figure out how to wire this thing, hah. As that armature moved changing contact points, the three wires on the right side were distinctly separate in achieving continuity. Light reading on these motors led me to believe that three of the terminals on the motor were separate electro-magnets, so it seemed the desired result would be.. energizing one for low speed, then two, then the third for top speed.

The board didn't and doesn't seem capable of such a feet. I struggled in trying to attach wires to it and decide how said current should even travel. The layout still doesn't make sense, hahah, but discovering a servo operated it was an exciting small victory for Nick and I.

I'll take another look at the picture I provided and attempt to lable how I attempted to route the wires.

Thank you so much for your help thus far. Oh, and for laughs, the fire was quite small. It was actually on the butt connectors used to finally close the circuit. That was a big part of what spurred me to think that the off switch should have been in the circuit between the battery and its ground rather than just protecting the radio transmitter thing. At any rate, it was too much power for any part of the circuit.

 

Pretty neat! I don't have any old-school RC experience, but do have an EE background! I'm guessing that speed selector board works like you say (energizing additional armatures in the motor for more speed, or different resistors like hasdrubal suggested) but doesn't look like the existing motor on there has that "feature". That board may also provide an option to reverse the polarity to the motor for reverse drive as well. So as it is, that board provides an "off", "forwards" and "reverse" depending on servo position, but no actual speed control. Do you have the radio that this came with, and have you gotten it to run the servos at all?

I think hasdrubal is right again, and the hoverboard battery is lithium. You could use only two of the lithium hoverboard cells in series for ~8 volts which would put you in the realm of what the RC stuff is expecting. But lithium batteries are no joke!

I bet a modern radio + receiver with PWM speed control + battery would work with that motor, but not sure how much money you want to put in to this project.

 

I'll share how I wired the device to clarify my own understanding.

Green dots indicate wires going to the battery, white to an on/off switch that ran directly to the remote control transmitter, yellow went to the one of the four mini tabs on the motor where I formerly had ground from the battery, and blue went to the other three tabs on said motor, one of which formerly had power (allowed testing the motor to see if it functioned)

If i listed orange as yellow or purple as blue, my apologies, I'm partially colorblind.. I'm gonna post this so i dont lose it while i tend to some personal matters. will revise later with responses!

 

I'm excited to update this thread! I may be able to get a pic or video of this car running some time soon.

The owner lost interest, I moved to a new home, and he had another untimely death in his family; that of his mother.. But!! He now has a new home, and some relatives were positively stoked to bring him into their family. I'm very hopeful regarding how things turned out despite the hardship.

And guess what? In his new family is a retired master tech Chevy guy. They're finishing what we started, and he'll get to have a functioning heirloom from his father.
Apparently while I'd worked with him we got a new motor, receiver crystals, and constructed a 4 cell lithium battery pack that I believe was 7 volts (two packs of 18650s in a series, then the two packs were wired parallel.) I'm super embarrassed by my work constructing that battery pack. It was janky. They're now doing a new remote, antenna, modern speed controller, and I hope to god a new battery pack too.

I don't know if he'll appreciate it fully until he's older, but I'm confident that he will some day, and I'm ecstatic that they're going to finish it. If I can get him to send me pictures or invite me over to see I'll absolutely post them up!!!

Thank you all so much for sharing your knowledge. I think we did a good thing here for a young man who's had to grow up entirely too fast. I really appreciate your contributions and I think he will too (teenagers are hard to read, man).

 

Love me the vintage RC's