# DC motor controllers



## DPittman (Mar 10, 2022)

I need some basic guidance regarding motor controllers for dc motors.  I'm browsing through Aliexpress and the lack of my knowledge combined with the poor product descriptions makes it a gong show.

I've salvaged a small 90v DC brushed motor from a treadmill.  On the motor it also says 450 watt, 5.5 amp and 3700 rpm.  I don't know how accurate these rating are but from what I gather it would be considered an extremely underpowered motor for a treadmill. 

I'm considering a project for this motor and realize that the end use of the motor would likely determine the type of controller I would need, however I think the two distinction would be foot control vs panel control.
Tool post grinder, seeing machine or a bead roller are a few of the possibilities that I might try to make use of this motor in.  The tool post grinder scenario I think is the most likely one.

I don't see any controllers on Aliexpress that list 110 volt, they all appear to be 220 volt?  Can those be used with 110 volt?  

It also appears that some controllers have to already have dc voltage supply?  I need to go from 110v ac to the dc voltage.

 My 90 volt specifications on the motor seems a bit unusual.  Can I use a controller with higher dc output without immediately frying the motor?


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## whydontu (Mar 10, 2022)

450 watt is about 3/4 hp, ignoring motor efficiency. More than enough for the uses you list.

Most of the higher wattage dc controllers seem to want dc input, this one is a bit low on wattage but would likely work, just sketchy at full power



			https://www.amazon.ca/24V-90V-Controller-Electric-Regulator-Permanent/dp/B076KPP92X/ref=sr_1_14?crid=3UHNG9PV5I76Z&keywords=dc+motor+speed+controller&qid=1646932013&sprefix=dc+motor+%2Caps%2C150&sr=8-14
		


My mill uses a KBIC125 for a 3/4 hp 90v dc motor. A bit pricy but bulletproof as long as you don’t apply power with the motor disconnected. This I know.






						KB Electronics KBIC-120 DC Motor Speed Control w/9884 Terminal Board : Amazon.ca: Industrial & Scientific
					

KB Electronics KBIC-120 DC Motor Speed Control w/9884 Terminal Board : Amazon.ca: Industrial & Scientific



					www.amazon.ca
				




The kbic has a pile of interesting features - remote shutdown, hold, 0-7v control signal input, adjustable ramp, adjustable output, etc. Mine is getting tweaked for an Arduino-controlled RPM/SFM/Cutter Type/Material automatic system for RPM


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## DPittman (Mar 10, 2022)

whydontu said:


> 450 watt is about 3/4 hp, ignoring motor efficiency. More than enough for the uses you list.
> 
> Most of the higher wattage dc controllers seem to want dc input, this one is a bit low on wattage but would likely work, just sketchy at full power
> 
> ...


Thanks for that info.  Yes I just ran across that first Amazon link you sent me. 
What are the main differences between that one you linked to and this one here
RioRand PWM DC Motor Speed Controller Switch Control 7-70V 30A Fuse(Black) https://www.amazon.ca/dp/B071NQ5G71/ref=cm_sw_r_apan_glt_i_CNEE9X3T7BB8448CTJ71?_encoding=UTF8&psc=1

I know the voltage output is lower but if I find one at 90 volts will it accomplish the same as your linked one?

Your second linked product is out of my price range right now. But I don't doubt that it is probably the best one to go with


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## whydontu (Mar 10, 2022)

DPittman said:


> Thanks for that info.  Yes I just ran across that first Amazon link you sent me.
> What are the main differences between that one you linked to and this one here
> RioRand PWM DC Motor Speed Controller Switch Control 7-70V 30A Fuse(Black) https://www.amazon.ca/dp/B071NQ5G71/ref=cm_sw_r_apan_glt_i_CNEE9X3T7BB8448CTJ71?_encoding=UTF8&psc=1
> 
> ...


The 7-70V 30A controller referenced needs a 70 volt DC supply.

You can run your motor on 70 volt, it just won’t reach the same maximum RPM.

Big snag is it needs a separate 70 volt DC power supply, and that costs $$$.

The first one I selected accepts regular 110VAC wall outlet power.

Here‘s a knock-off of the KBIC controller









						61.51C$ |110v 220v Ac Input 90v 180v Dc Motor Speed Controller 10a - Motor Controller - AliExpress
					

Smarter Shopping, Better Living!  Aliexpress.com




					www.aliexpress.com
				




I‘ll spend a few minutes seeing if I can find one with free shipping


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## whydontu (Mar 10, 2022)

Assuming this controller has built-in current limiting, it should work with your motor









						17.57C$ 30% OFF|Dc-51 Input Ac110v Dc Motor Speed Controller Permanent Magnet Brush Motor Controller Output 24v36v60v 90v Emergency Stop - Dc Motor - AliExpress
					

Smarter Shopping, Better Living!  Aliexpress.com




					www.aliexpress.com


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## combustable herbage (Mar 10, 2022)

I guess it would depend on the application but is it conceivable to use the controller from the treadmill,  change the switches to something smaller you have speed control and on off even a funky deadman switch?


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## whydontu (Mar 10, 2022)

combustable herbage said:


> I guess it would depend on the application but is it conceivable to use the controller from the treadmill,  change the switches to something smaller you have speed control and on off even a funky deadman switch?


And you can get a display that shows how many calories you would have burned if you went jogging instead of standing next to the lathe


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## whydontu (Mar 10, 2022)

this one explicitly states it’s a controller suitable for use on the mini lathes, and has current limiting









						34.26C$ |Ac110v Or Ac 220v Motor Speed Control Controller For Dc 0-90v 0.01-400w 1/3ph Motor Amplifier - Home Theater Amplifiers - AliExpress
					

Smarter Shopping, Better Living!  Aliexpress.com




					www.aliexpress.com


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## DPittman (Mar 10, 2022)

combustable herbage said:


> I guess it would depend on the application but is it conceivable to use the controller from the treadmill,  change the switches to something smaller you have speed control and on off even a funky deadman switch?


Nope all I got was the motor, no controls or electronics.


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## DPittman (Mar 10, 2022)

whydontu said:


> The 7-70V 30A controller referenced needs a 70 volt DC supply.
> 
> You can run your motor on 70 volt, it just won’t reach the same maximum RPM.
> 
> ...


Hmmn thanks for the work and info.  That kbc knock off is still really expensive.  I'm guessing it must be way better than the other options?  It looks very similar to the board in my DC variable speed lathe.
I think I'll give one of the other ones you listed under $40  a whirl maybe.


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## DPittman (Mar 16, 2022)

So I got a dc motor controller from Amazon

DC Motor Speed Controller, 24V-90V Adjustable Single Phase Motor Speed Controller for 24V, 36V, 90V DC Motors https://www.amazon.ca/dp/B07FZ38M54/ref=cm_sw_r_apan_glt_i_PTWNW5D4HPB0XYE3G0G2?_encoding=UTF8&psc=1

And just trying it out on the motor now.  I've only been able to try the motor on 12 volt and 20 volt batteries and it seems to run ok on those.  The brushes look a bit rough but I think ok.




The dc controller seems to make the motor really hum loud and it will only run at a low speed and rather roughly. The rheostat dial seems to make it run worse by no faster as I crank it up. Definitely something not right there.  
I'm wondering about testing the output dc voltage with a multimeter but 
@whydontu 
suggested above that it was not good to run his KBIC controller with the motor not connected.  Is that ok with my cheap controller?  Any suggestions?


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## whydontu (Mar 16, 2022)

As long as there is a motor connected, you can read the motor voltage with a multimeter by reading across the + / - connections. How much current does the motor pull at 20 VDC?


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## DPittman (Mar 16, 2022)

I think I'm going to jump ship before I fry something.  There's alot a brush sparking and noise when running the motor with that thing.  When I run  the motor with a 20 volt dc drill battery the motor seems to run smooth with good torque (but of course not real fast) .  This is probably why people pay much more for the controllers like you have.


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## whydontu (Mar 16, 2022)

How much does the controller weigh? I'd be happy to test it in my shop, I have quite a bit of accurate test gear and could run diagnostics. My guess is the motor current is too high at low RPM and the controller is struggling. Could vent be a simple as needing a capacitor across the motor DC supply to smooth out PWM noise.


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## DPittman (Mar 16, 2022)

whydontu said:


> How much does the controller weigh? I'd be happy to test it in my shop, I have quite a bit of accurate test gear and could run diagnostics. My guess is the motor current is too high at low RPM and the controller is struggling. Could vent be a simple as needing a capacitor across the motor DC supply to smooth out PWM noise.


Thanks for the offer.  The thing weighs about 3/4 of a pound (.33kg).

I think I will see if I can return it.  I guess I will have to be on the lookout for wrecked treadmills in hopes of finding a useable controller.  I don't think I can spend the money a good KBIC controller would cost.  I'm just playing.


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## DPittman (Mar 16, 2022)

I just remembered... I bought a motor speed control for my lathe a few years ago thinking it might be the problem, as it turns out it wasn't but I kept the controller anyhow just in case someday it fried.  Low and behold it is a KB electronics Inc controller!

I think I want to keep it for my lathe for the just in case someday scenario but I'd also like to use it to try out my motor more fully. HOWEVER  I can't risk frying it because my lack of electronic knowledge.  Would you 
@whydontu 
be willing to help/guide me to wiring it correctly?


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## VicHobbyGuy (Mar 16, 2022)

I grabbed a couple of free treadmills recently to get the motors for possible use as:
a)upgrade for my 7x14 lathe
and/or
b)variable speed motor for my drill press.
I watched a lot of YT videos and read a bunch of online info.
I liked the approach from 'The Aussie Shed' guy: cheap AC controller feeding a bridge rectifier then DC to the motor.





I bought this controller (same item is cheaper at AliExpress if you can wait)
https://www.amazon.ca/gp/product/B082ML24LH/

Bridge rectifiers are cheap and common; I had a few on hand.
Something like this bolts to an empty spot onthe heat sink:
https://www.amazon.ca/Twidec-Housing-Electronic-Rectifier-KBPC-5010/dp/B07PJ6168B/

I had the components but didn't get around to assembling anything until I blew (easily) the controller on the mini-lathe and sent that off to Peter Brush (olduhfguy) for repairs. It worked OK on the treadmill motor (a '2 HP' 90 volt), better after I swapped the pot in the controller for a lower value one. I put everything into a good (grounded) metal box with a fuse, switches (ON/OFF, FWD/REV) and hooked it up to the minilathe motor and it works fine. The speed knob needs to be advanced from about 7 o'clock to 11 before it starts up, and I haven't measured the RPM but I was more concerned with decent low RPM performance and it does that OK. I've done a few little projects and made a few mistakes since, and it's still doing fine. I have the repaired controller back from Pete Brush but haven't bothered to re-install it.


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## whydontu (Mar 16, 2022)

DPittman said:


> I just remembered... I bought a motor speed control for my lathe a few years ago thinking it might be the problem, as it turns out it wasn't but I kept the controller anyhow just in case someday it fried.  Low and behold it is a KB electronics Inc controller!
> 
> I think I want to keep it for my lathe for the just in case someday scenario but I'd also like to use it to try out my motor more fully. HOWEVER  I can't risk frying it because my lack of electronic knowledge.  Would you
> @whydontu
> ...


That’s a good board, easy to wire. 

L1 goes to 120 volt AC neutral
L2 goes to 129 volt AC hot 

A+ goes to motor positive
A- goes to motor negative

You need a 5K to 10K pot to adjust speed. Connects to P1 P2 and P3. 

This one is easy to wire but a bit pricey:



			https://www.amazon.ca/Taiss-LA42DWQ-22-Potentiometer-Converter-Resistance/dp/B07DJ7GXTN/ref=sr_1_1_sspa?crid=3KFM2AB8OGQNF&keywords=5k%2Bohm%2Bpotentiometer&qid=1647480292&sprefix=5k%2B%2Caps%2C145&sr=8-1-spons&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUExUERDVTFLOEs2TDRTJmVuY3J5cHRlZElkPUEwNzk2NTE1MzM0TURCMExaWjhEQyZlbmNyeXB0ZWRBZElkPUEwMjY4NzAzMkNBR1k5N0VZMUgxRyZ3aWRnZXROYW1lPXNwX2F0ZiZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU&th=1
		


This one is decent quality but needs to have the wires soldered on:



			https://www.amazon.ca/1pcs-RV24YN20S-B201-B501-Potentiometer/dp/B07YJGPCLH/ref=sr_1_25?crid=3KFM2AB8OGQNF&keywords=5k+ohm+potentiometer&qid=1647480360&sprefix=5k+%2Caps%2C145&sr=8-25
		


manual:



			https://acim.nidec.com/drives/kbelectronics/-/media/kbelectronics/documents/dc-drives/manuals/kbic_manual.ashx?la=en


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## DPittman (Mar 16, 2022)

whydontu said:


> That’s a good board, easy to wire.
> 
> L1 goes to 120 volt AC neutral
> L2 goes to 129 volt AC hot
> ...


Awesome thank you for all the help.


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## DPittman (Mar 18, 2022)

whydontu said:


> That’s a good board, easy to wire.
> 
> L1 goes to 120 volt AC neutral
> L2 goes to 129 volt AC hot
> ...


Oh boy that didn't go so well I'm afraid.  I got a potentiometer like the first one linked to (but a 10k) and hooked up the board as suggested.  Motor started up and it was very sparky on the brush end.  I quickly unplugged and tried once more and nothing not even a hum.  Tried the motor again just on a 12 volt battery and it seemed okay.  Man I hope I didn't fry this board.  How would I test it?


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## whydontu (Mar 18, 2022)

Put a 100 watt (minimum) 120VAC filament light bulb in place of the motor. If it lights up the board is OK.

very odd. can you post a photo of the motor nameplate?


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## DPittman (Mar 18, 2022)

whydontu said:


> Put a 100 watt (minimum) 120VAC filament light bulb in place of the motor. If it lights up the board is OK.
> 
> very odd. can you post a photo of the motor nameplate?


As you can see the brushes are less than ideal but seem okay with low 12volt voltage?


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## VicHobbyGuy (Mar 18, 2022)

whydontu said:


> Put a 100 watt (minimum) 120VAC filament light bulb in place of the motor. If it lights up the board is OK.


If the bulb lights up and you can control the brightness with the pot would be the next step.

Did you put a fast blow fuse (15A?)  in the AC line and DC line to the motor? And the pot wiper was connected to P2? And the 'Horsepower resistor' is the correct value?

It's interestng that your controller is labelled KBLC, not KBIC.


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## DPittman (Mar 18, 2022)

No fuse in line. And yes I believe I have the wiper connected to P2.  I'm going to try to hook up the light bulb test.


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## whydontu (Mar 18, 2022)

motor nameplate looks well within the specs for the controller. If the lightbulb test works, wire the motor in parallel to the lamp and try again.


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## DPittman (Mar 18, 2022)

Whew! The light bulb lit!  What will running it with the motor tell me?  I'm guess now that the brushes might be the fault?


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## whydontu (Mar 18, 2022)

If the lightbulb lit, then the controller is probably working. These controllers tend to be all or nothing. Does the pot work to adjust the lightbulb brightness? 

Having the lightbulb presents a steady load on the controller. Without the bulb, if the motor is arcing the load is fluctuating and might be confusing the controller. 

Do you have the correct HP resistor?


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## Tom O (Mar 18, 2022)

How’s the spring on the brushes? On my Craftex they heated up and lost some spring tension.


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## DPittman (Mar 18, 2022)

whydontu said:


> If the lightbulb lit, then the controller is probably working. These controllers tend to be all or nothing. Does the pot work to adjust the lightbulb brightness?
> 
> Having the lightbulb presents a steady load on the controller. Without the bulb, if the motor is arcing the load is fluctuating and might be confusing the controller.
> 
> Do you have the correct HP resistor?


I "think" I have the right hp 


resistor as it is supposed to be right for my 3/4 hp lathe motor. Pic attached.
Yes the pot works welll to adjust bulb brightness.
The brush springs seem fine to me.


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## DPittman (Mar 18, 2022)

So does this look right for parallel wiring?  Alligator wires on left will go to A+ and A- on the board and the red wire on the right goes to motor motor positive and the left black goes motor negative.


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## whydontu (Mar 18, 2022)

DPittman said:


> So does this look right for parallel wiring?  Alligator wires on left will go to A+ and A- on the board and the red wire on the right goes to motor motor positive and the left black goes motor negative.View attachment 22114


that’s it


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## VicHobbyGuy (Mar 18, 2022)

If it were my experiment, I'd put the bulb in series with the motor to act as a current limiter. Or put the bulb in the AC line to limit current there.
Also,  I'd definitely add those fuses to the system. 

Are there green /red LEDs on the board as mentioned in the manual?


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## VicHobbyGuy (Mar 18, 2022)

DPittman said:


> I "think" I have the right hp resistor as it is supposed to be right for my 3/4 hp lathe motor. Pic attached.


Yes, that looks about right for the resistor. Check that the CL (current limiter) pot is in the mid-point of its adjustment range, too.


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## whydontu (Mar 18, 2022)

VicHobbyGuy said:


> If it were my experiment, I'd put the bulb in series with the motor to act as a current limiter. Or put the bulb in the AC line to limit current there.
> Also,  I'd definitely add those fuses to the system.
> 
> Are there green /red LEDs on the board as mentioned in the manual?


from expensive experience, these controllers really dislike intermittent loads. Page 13 of the manual. Open armature wiring causes immediate release of the magic smoke. That’s why I suggest  in parallel.


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## DPittman (Mar 18, 2022)

Ok tried bulb in parallel and motor runs with a bit of sparking at low speed and bad sparking and bit of smoke as I cranked up the pot.  Quit before all the magic smoke escaped.  I'll see if I can find new brushes.


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## VicHobbyGuy (Mar 18, 2022)

DPittman said:


> I'll see if I can find new brushes.


There's still a fair bit of carbon left on the brush in the picture, so you could use sandpaper around a dowel to sand back to a smooth curve. I've done that. Also, I have had a situation where that spring decided to just coil up in the passage and not press the brush down effectively. I'd try to have a look at the commutator if there was an easy way to do that, sometimes they get a dirty film which affects the contact.


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## DPittman (Mar 18, 2022)

VicHobbyGuy said:


> There's still a fair bit of carbon left on the brush in the picture, so you could use sandpaper around a dowel to sand back to a smooth curve. I've done that. Also, I have had a situation where that spring decided to just coil up in the passage and not press the brush down effectively. I'd try to have a look at the commutator if there was an easy way to do that, sometimes they get a dirty film which affects the contact.


Thanks for those suggestions.  Yes the commutator does definitely have a film on it but not much wear.


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## Tom O (Mar 19, 2022)

It looks like some particles are close to bridging maybe give them a scrape out while it’s apart.


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