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I need some help with which motor controller to get! Answered

Hi All,

I need to help with working out what motor controller I need for this dc motor.

I'm converting a old vibration exercise machine into a vibrating cleaner, I've done a test run and it seems to work pretty good but the problem is the exercise machine has set workout programs and the longest is 10 minutes, which means if I want to clean something for an hour I have to keep going back to reset the machine!

If pulled apart the machine and it has a DC motor but my knowledge of them is pretty limited, I've searched for advice but I'm struggling to decipher what I'm going to need.

I'd like to use the plug from the machine so it mains powered, variable speed would be brilliant.

So what controller do I need?



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1 year ago

Problem with treadmills and similar is that they almost always use DC motors that are not designed for mains voltage.
Unless you are in the US with 110W coming from the wall you need a rather complicated controller.
Since you already have everything you might need in the salvaged electronics it might be easier to figure out how to modify the part for the training programs.

E.g: The motor controller must get the signals from somewhere - the set exercise program.
With abit of luck it can be as simple as having a ON-OFF-function plus a PWM or voltage signal for the required speed.
If it is also cheap enough to comes without any safety feedback, like stalled motor and such the conversion is doable.

To do it from scratch you would need a power supply or diver that can go from 0-100V DC with at least 2A, preferably 3A to be on the safe side.
Can be done with a fixed 100V supply and added PWM controller for example.
However, just the required parts for this can be rather expensive.
But I am sure our resident experts will chip in with more ideas on these two bits :)
It's weekend, so if in doubt give them a few days to reply - not everyoe might be in isolation....


Reply 12 months ago

thanks for the reply.
You're right about the cost, the only controller I have found was $122 (plus shipping to UK) which goes against the whole budget/DIY ethos of the project, for that money I could almost buy a ready made vibrating cleaner.

I'll have a look at the current exercise control board and see what I can work out!
Thanks for the pointer!

Jack A Lopez
Jack A Lopez

12 months ago

Well, if we really knew what we were doing, I think it would be possible to re-wire or re-program the existing controller.

However, I do not blame you if that seems too complicated. I mean, in truth it is complicated, to figure out what component does what, and which wires go where, and in total, how the existing controller does what it does.

By the way, if you ever want to witness someone with a very superficial understanding of electronics, pondering what does what on a circuit board, there is this old video (it can be found on Youtube) titled, "Björk talking about her TV." In this video the Icelandic singer also explains the scienmagifics of why you are in no danger of being hypnotized by your television set, in case you were worried about that.

Getting back to the problem at hand, I think, sort of the cheap-and-dirty way to do this, is by using a triac based lamp dimmer, to give some "chopped up" AC mains power, with less than the full RMS AC voltage. Then rectify the chopped AC into DC, using some kind of rectifier circuit.

Actually, in the Wikipedia article for "Rectifier," section titled, "Rectifier circuits," there are some nice pictures and desciptions of the usual circuits for this, including "half wave" and "full wave" and so forth, if you have not seen these already.


Regarding power converter modules, and variable voltage power supplies, that you can buy, like on eBay, typically from Chinese eBay sellers...

The only problem with buying a power converter, is the cost of a power converter tends to scale with the amount of power it can throughput. So a module capable of 10 watts power throughput would likely be very cheap, but something capable of 200 watts max power throughput, would be much more expensive.

Your motor is rated at 200 watts max, at 100 volts DC, or at least that is what the nameplate on it says.

Actually, Downunder35m explained this in a previous comment; i.e. the character of this kind of power supply.