Simple Variable Speed Treadmill Motor Electrical Conversion


Hi, this is Barry. Welcome back to the workshop. In this video I am going to show you how I
took these electronic components from a used treadmill and converted them for use as a
variable speed drive on a power tool. Ok, so here are all the parts that I removed
from the treadmill. You have the input and display, the speed
controller for the motor, the motor itself, this circuit board which is a control circuit,
and the motor for the incline, which is a linear actuator. I am going to, at the end, I don’t want to
use this input because it’s too big and bulky, and I don’t need it. I’m certainly not going to use the incline
motor. And since I’m not using this input, I also
don’t need this circuit. So I’m going to show you how I am going to remove those. But before I get into that, I’ll just plug
everything in to make sure that everything is working. If you are using this off a treadmill, there’s
this little clip thing that you clip to your body and then if you fall off or trip, it
pulls this thing out, so you need to have something in there for this safety switch. I’m using the cord that came with the treadmill,
and I’ll go ahead and plug it in. While it boots up, this little incline motor
does a little dance. I’m mostly concerned with the motor and the
variable speed, so I’m going to manually set the speed and make sure that the motor spins
up. And it does. I can adjust the speed…there’s a lag, but
it seems to work. So I know everything is working. At least when I start. So hopefully it will still be working when
I’m finished. I’m going to go ahead and start removing the
parts that I don’t need. I’m going to do those one at a time so you
can see that. I’m going to unplug the power just for safety. The first thing I’m going to remove is the
incline motor. There is a sensor which it looks like I already
disconnected that sends the position of the incline to the control circuit, which we don’t
need. And also, there is a white, red, and black
wire on this. And it says, “white – neutral, red – down,
and black – up”. I’m going to make a note of those because
I may want to use this motor for something later. So we’ll get that out of the way… Alright… so that shouldn’t affect anything. The next thing I need to do is this board
has a Pulse Width Modulator based on the inputs from the input board. It sends a pulsed signal to this speed controller
and that’s what determines the speed of the motor. And it send that through these three wires. There’s a red, white, and black here. And I need to.. I want to take those out of the circuit, I
need a way of controlling it. The way I’m going to do that is with a potentiometer. In this case I have a 10K potentiometer. I’ve certainly seen other people use different
values and I believe that would probably affect the speed but this is what I have today. I may change it later. I soldered a white, red, and black lead. The white is the wiper, and the red and black
are the other two. If you get the polarity switched, then your
knob will turn left to go faster. You can just flip those around, which I actually
had to do. So what this is going to do is replace that
PWM circuit. I’m going to disconnect the three wires from
the speed controller input, and get those out of the way. And connect those red, white, and black. So if everything is working correctly, then
I should be able to control the speed of the motor using this potentiometer instead of
this big clunky board. So let’s plug that in right now and make sure
that it’s still working. …plug that in… Now there are live wires here, so you have
to be careful what you’re touching. I’m just going to hold the case for this potentiometer
and turn that knob clockwise. So I can turn it on and off and adjust the
speed with the potentiometer. So that’s exactly what I was looking for. And that also means that I don’t need this
big clunky board, and I don’t need this circuit, So I’m going to remove those. This input is connected with this wiring harness,
so I’m going to go ahead and get that out of the way. So the last thing I need to do is get this
circuit board out of the way. Both of these boards, the speed controller
and this board are powered by 120 volt AC. There’s a white, and in this case a blue wire
for the hot. This has two terminals, it say’s it’s an IN
and an OUT, but it’s really just a parallel… So I should be able to disconnect the hot
and neutral from this board, instead of jumpering, and then just connect them straight into that. So I’ll go ahead and disconnect the HOT…
again, this is unplugged. And the neutral. This is straight from the power cord. And I can hook the neutral straight into this
board. It’s marked white. Now for the HOT, there’s a pair of blue wires
that go to the motor. And I understand that there is a thermal switch
in the motor, and if the motor overheats, it will shut off the power to it. So you can either run it with or without that. I like the idea of having the protection circuit,
and I don’t think it will affect the power, so I’m going to leave it in. So I’m going to run the hot from the power
cord, through the motor, and fortunately there’s a terminal connector here, and I’ll just plug
that in. At this point, this board is disconnected
so I can get that out of the way. So again, the power… the neutral goes straight
to this board, and the hot goes through that thermal switch on the motor and then into
this board. I could take that out, but I’m going to leave
it in. There is a power switch here on the cord that
says “reset” so I assume there is some kind of a breaker in there. I’m going to leave it in the circuit. At this point, I should have everything I
need to mount this motor and set up the drive, and be able to control it with this potentiometer
and the speed controller. So let’s test that and make sure that we’re
working. I plugged it in. I’m being careful not to touch anything live
but there is a red light here so I do have power. And if I turn the potentiometer… [motor
turns on] So everything is working. If I wanted to right now I could run it in
this configuration. There are a couple of details that I want
to show you, though. I’m going to zoom in first… OK, at this point I have everything that I
need to use this as a variable speed drive. I have the motor, the speed controller, the
potentiometer, there’s a main power switch, and the power cord. That’s really all you NEED to use this. Of course, you’re going to have to set up
the pulleys however you’re going to use it to drive the tool, but this is all you need
to get started. There a couple of enhancements that you might
want to consider, and I’ll show you those. One of them… this is a DC motor, and DC
works on polarity. So if I reverse the polarity of the inputs
to this motor, I should get reversed direction. I’m going to show you that it does indeed
work. So, unplug the power. The red and the black wires are the drive
for the motor. There is a pair of blue wires here that I
mentioned earlier are the thermal switch. So if I switch the polarity of the red and
the black, then I should get reverse direction on the motor. So let’s plug that in and I’ll test it to
be sure it works. And turn the potentiometer. And it does spin in the reverse direction. So if I want to have a reversable motor, I
can install a double pole-double throw switch on these two leads, in between the speed controller
and the drive motor. And there’s a basic circuit, I’m not going
to show it right now, that you can use to flip the polarity. You need a double pole, double throw switch
and there’s a couple jumpers that you use… I’m going to switch this back for right now. You do need to know that the flywheel on the
motor is screwed on to the motor with reverse threads. So if you run it backward, there is a chance
that this flywheel could come loose. On my motor, it’s REALLY on there, I don’t
think it’s going to go anywhere, and I’m not going to run it in reverse very much. Just something you want to consider. So the other think that I wanted to show you
besides being able to reverse the polarity and change the direction of the motor is there
is a soft start feature on this speed controller that… it’s basically a safety for a treadmill. You don’t want a treadmill to just ramp up
and go straight to full speed. The way this controller works is that you
have to start slow and ramp up slowly. That’s kind of an issue with a power tool
where you’re turning it on and off and you want it to come back up to the same speed,
and not have to keep fiddling with the potentiometer every time. And I’ll show you what I’m talking about. I”ll plug it in. I have the potentiometer all the way off… I’m going to turn it up and get the motor
going. So the motor is spinning, I’m going to leave
it low so that you can hear me, but imagine this is on a wood lathe and I need to change
tools, I want to turn it off for a moment. I turn the switch, the power to the unit,
off. And then when I turn it back on, nothing happens. In order to get it to spin back up, as it
is right now, I have to turn the potentiometer all the way down, then back up. And chances are that I’m not going to bring
it back to the exact same speed that it was. So every time that I stop and start the motor,
I have to adjust he speed. That’s going to make the control of the speed
a little bit more difficult. Especially for things like a wood lathe where
you’re stopping and starting pretty often. So what I found, and this is a little research
and a little trial-and-error on this unit, if you disconnect the red lead, it has the
same effect as turning the potentiometer down. And you can control the “on” and “off” of
the motor by disconnecting the red lead. I’ll show you. These are live wires, so you have to be carefull… I’m not touching any of the 120 volt wires
while this is on. So if I turn the motor on, and it’s running,
again I showed you that if I turn it off and on here, I cannot get it to start. I have to use the potentiometer. But I’m going to leave the potentiometer on,
and turn that down so you can hear me. If I disconnect the red wire, it removes the
input signal so there is no longer current going to the motor. When I reconnect the red wire, it turns back
on, and since the potentiometer hasn’t moved, it’s the same speed. So I can turn the motor off and on by removing
the red wire from that circuit. So if I want to have an on / off switch that
doesn’t require modifying the potentiometer, I can put a switch on that red lead on this
potentiometer, and turn the motor on and off without having to change the potentiometer
setting. Now I’ll still have the main power switch
which will turn off the power to everything but I’ll be able to control the motor on and
off without changing the potentiometer. And that’s probably what I’m going to end
up doing. You may or may not want to, if you care about
that speed controller, or not. But that’s a common issue that I’ve read about
and I believe that’s going to be the solution I go with. So everything I have shown you is just for
the treadmill that I found. This is one example. Your motor and your controller, your circuits
may be different, so exercise caution. But I just wanted to show you, for this treadmill,
what I was able to get working as far as the electronics. And hopefully you’ll find that useful if you’re
trying to reuse a treadmill motor as a variable speed controller. So I hope you enjoyed this video, and I hope
you found it useful to see how I reused the electronics from a treadmill to later use
as a variable speed drive on a power tool. If you have any questions or comments, please
put those in the section below. And if you haven’t already done so, please
subscribe to the channel. I really appreciate it. Thanks for watching. I’ll see you next time.

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