What Does That Treadmill Motor Coil Do? 

Just as a capacitor will smooth out voltage ripple on a voltage source from a power supply, this inductor smooths out the CURRENT. At each make/break of the commutator, the inductors magnetic field collapses, and self induces a current to smooth out the CURRENT ripple. This allows the power supply to appear as a current source, as opposed to a voltage source. The collapsing magnetic field in the inductor at the break of the commutator on the motor, provides additional current from the inductor for the next make of the commutator.

Barry, just discovered your site, its great, but where are you now, please come back, there must be a lot of people missing your great videos. regards Colin. UK.

Excellent video. Nice to see the difference with inductor and without.

Thanks Barry just what I was looking for. I have pulled apart several treadmills I got for free and 1 had a choke like yours and the other 2 had emi filters housed in a metal box. To be safer / safer? I decided to use the emi filter as they run both active and neutral through the unit as well as the metal box being earthed. Also ran the ferrite coil in the line to the motor. Some of the other benefits I have heard of but can’t prove is that the filter can help block a spike from blowing the motor controller and the dc motor itself will last longer as the voltage it receives is smoother. I think your demonstration helped show how much smoother the motor was. Cheers and thanks, Stuart. 🇦🇺

Thank you for taking the time to record, edit and post your video. Cheers

The choke significantly reduces arcing at the motor brushes resulting in longer motor life. You should always use the choke unless you are trying to burn up the brushes on purpose.

Thanks Barry for the update. I was watching your previous video and was wondering why the transformer? Now I know that it was a coil for induction purposes. Thanks for taking time to make a video to explain this rudimentary electrical design. Cheers!

Great video. I am building a belt grinder and could not decide if I should buy a controller and bridge rectifier plus a Potentiometer or salvage the treadmill controller and just add the pot. Is a 10 k Pot sufficient to provide a proper range of speed control.

I'm glad I found your Channel I want to go out and buy an old treadmill now

Hi Barry. Good video. I have some questions. What is the function of the heavy flywheel? I’m going to hook up my lathe to an SCR driven variable speed drive with a reverse capability. Should I remove the flywheel or somehow secure it so it doesn’t spin off? Thanks, Paul

Barry, great video. Only thing is what size is the choke? Thanks for your effort.

Barry, I still don’t see where you say what the coil really does. As I understand the circuit, it is an inductor, and I think there will be a “free wheeling diode” on the board. Which means that the purpose of the inductor coil is to limit and smooth the current pulses that are coming from the rectified AC driver. The SCR or TRIAC driver can apply an instantaneous voltage, but the inductor limits the current. And even after the driver turns off, current will continue to flow for a bit. This will take a bunch of the electrical noise out of the circuit, and clean up the DC to the motor.

I think the ramping up of speed has more to do with the controller ramping the voltage so you don't have a sudden full speed on the treadmill...not a pretty picture! I think it's called a "soft start",. which can be a problem with using the controller from the treadmill.

good night thank you very much for this video, my question I can with this potentiometer keep using my treadmill and avoid using the interface

Barry thanks for the video I got a old thread mill out of a junk pile and the mice had eaten the wires off the inductor I was able to get the motor to run after I watched your video but I can’t tell where to hook the inductor up. Any help would be appreciated. PS I’m not and Electrican just a tinkerer.

I believe you're correct. The coil is functioning as an inductor to thwart both the inrush current on startup (it's fairly drastic) and it also spreads out (softens) the speed changes because in an inductive circuit, current always lags voltage changes. Usually you see capacitors in parallel to inductive motors like that both to equalize the reactance and to deliver maximum current at startup and quick response to speed changes, and that's totally an option here if your needs warrant it. In a treadmill, however, you want the opposite to make the changes as soft as possible so it doesn't throw the user off (despite how funny that appears). Running without either a capacitor OR inductor to condition the load will always shorten the life of the motor due to heat loss during longer transitions from stall to run and speed changes. This would be super fun to demonstrate on an o-scope. You'd have to use current clamps, or an equivalent current to voltage converter to sample it since an o-scope shows voltage in the frequency domain but that's totally doable.

I've just dismantled two different make and model treadmills and neither of them had the inductor coil on the control board. Do you think this may have been eliminated in some treadmills?

Awesome video. I need some help though. I have an MC-60 treadmill speed controller. I'm trying to eliminate the soft start and stop. Putting a switch from the board (red wire to the motor) gives me what I'm looking for but I am concerned about whether the board needs the load from the motor. Is it safe for the speed controller to run with a switch on the motor lead?

Will this choke work on an 110V A/C current for a Fan? I used a speed controller and at low speeds it hums a lot

There are a 100 inductive chokes available through Hammond Mfg. They all offer different for inductance, DC current, and resistance. Is there a way to identify the needs for a treadmill motor? I have a 3hp, 100 volt, 23 amp motor. I'm running an MC-60 board. I'd like to add a choke, but not sure what size. Any direction would be appreciated.

Can you share the specs from the label so I can find one on the web?

Could you hash together a wiring diagram for your assembly? I believe I have the exact collection of parts but was short on time taking the treadmill apart. Some of my wiring is much less plug and play.

great video. was it ac power supply you used? where is the part that converts the ac to dc voltage? seen no rectifier!thanks

What about bypassing the blue wires, would those cause problems? I hear that the blue wire has overheating protection.

i have the same motor but it's 90V, i was wondering how it's possible to go down 120v to 90V without a transformer in that electronic board, i'm going to buy one because i was trying to do an analog H bridge but i have to many problems with that circuit

Great Video :-) Where does one get a coil (Choke) like the one you have?

thank you for doing this video....i took this out of my build...it does not seem as wacky sounding as yours. is that a mc-60 controller?

Are you familiar with any of the newer treadmill motor controllers? I have a Sole F80 treadmill motor and the controller that went with it. I can't find anyone who knows how to pair the two together for a shop build project.

Barry, is the flywheel needed for a belt grinder?

Can you please cover the blue wires in more detail? I havean identical motor but not the controller board, So Im going with a 10kw SCR and a bridge rectifier. Not sure aboutthe blue wires.

Good info.. I've been wondering about this. Can you take an up close shot of the tag on the inductor choke? Mine has no info on it and I need to replace it. Thanks for the video....

Nice thank you...I was wondering about that too.

PLEASE TEACH ME ON HOW TO RUN THAT MOTOR USING A DC INPUTS

Please how u connect poinmeter in board u connect 3 line

I have a proform 625 when powered on the display console just blinks and the treadmill doesn't run any idea what could be wrong

Yes, you can tell a difference... :)

Explain how u can connect

Boy am i glad i held on to the inductor. I was gonna toss it, but i thought it was a transformer that i might use one day

can I remove the flywheel?

The coil reduces the amp draw to the motor, due to the high resistance of the coil

you are lost when you say the transformer have at least 4 wires ,no,no,no,no 3 wires not 4 ,the choke is for smooth the current ,,,,(delay ),,,,,, in the DC motor also a large resistor work too, for start a AC motor Compensated Transformer is used, or var transformer ,or delta /star connection ,etc,etc

Please how u connect poinmeter in board u connect 3 line