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  • schoolie 4:43 pm on June 15, 2013 Permalink | Reply
    Tags: 555 timer, Bird Blaster, , , Orbit 62035, peacocks, Pets, PIR Motion Detector, sprinkler valve   

    The Bird Blaster v1.0 

    I keep a pair of peafowl as pets. Peafowl (the male in particular) like to look at themselves in anything that’s reflective. They also like to eat potted plants. This leads to a lot of peacock poop and damaged plants on our porch, which leads to me being in trouble with my wife :). Being an engineer, I figured the only reasonable solution would be to make a motion activated sprinkler to discourage them from hanging out near the house.

    Peacock and Peahen on the patio (they’re not supposed to be on the patio…)

    This was my first real electronics project, starting in the fall of 2011. My plan was to use a motion activated security light, a sprinkler valve from an automatic watering system, and a custom circuit to connect the two.

    (Read the rest of this post…)

  • schoolie 10:14 pm on May 21, 2013 Permalink | Reply
    Tags: 555 timer, , ,   

    An alternative MC-2100 dashboard replacement circuit 

    Terry’s dual 555 circuit


    As discussed in the comments of earlier MC-2100 related posts, Terry has been working in parallel to create a circuit capable of generating the variable duty cycle PWM signal that the MC-2100 requires to operate. He’s written up a very thorough summary of his design process (click for the PDF file).

    Terry’s circuit uses two 555 timers (or a single 556), two potentiometers (one is a trimmer), and various capacitors and resistors. This is a great way to get the MC-2100 working without the dash panel if you don’t have a comparator on hand.

    • Doug 12:04 pm on October 31, 2015 Permalink | Reply

      Hi Terry,
      Hope you see this post here
      I built Schoolie’s 555 – LM393n circuit but was not able to get it to work with the MC2100

      Then I built your dual 555 timer board and was able to get my MC2100 to run my motor

      A couple of notes on my build using your PDF build document

      The circuit would not respond until I added a .68uf cap across the Black and Red wires coming from the MC2100. See my picture
      Once I added a cap across the incoming 12v voltage supply, the circuit began to send pulses to the MC2100
      I only discovered this because I hooked up my multi meter to measure the 12volt supply and the circuit started working. When I removed my meter, the circuit stopped working. I unhooked my meter and touched a .68 cap across the voltage supply and the circuit starting work. I saw Schoolie had a .47 on his circuit and so it looked like a good thing to add to your circuit

      The optimal resistance I found on my build for the combo of R3 + R2 was 31k

      Terry, as you noted in your PDF build document, turning off the MC2100 and then turning it back on resulted in the circuit no long working. I added a momentary switch between R5 pot and the 12 volt power supply
      Tapping the momentary switch and breaking the voltage to R5 and then releasing the momentary switch works like a charm.
      After breaking and restoring the 12 volt supply to R5 pot, the circuit starts up and pulses the MC2100

      I am open to any modifications that may be needed on my build
      Does the circuit need a filter on the blue wire to prevent the motor from messing up the pulses from the 555 board like schoolie di on hi circuit?
      I was curious if you have made any changes to your original circuit since creating your PDF document?

      Thanks, Doug
      Here’s a pic of my breadboarded circuit using Terry’s dual 555 timer circuit

      • Bryan 7:53 pm on November 17, 2015 Permalink | Reply

        Minor correction to your wording – you installed the momentary switch on the R2 (not the R5) pot. Wondering if this will work on the 555/LM393 circuit…

    • Doug 10:33 am on November 2, 2015 Permalink | Reply

      Thanks to you Terry and Schoolie for posting this info. I would have chucked my MC-2100 in the trash and purchased a MC-60 if it were not for the info posted here and on Schoolies blog.
      My finished project can be found on my web site here.

    • Doug 10:34 am on November 2, 2015 Permalink | Reply

      And here is a you tube video of my MC-2100 and your 555 timer circuit in action.

      • Doug 10:36 am on November 2, 2015 Permalink | Reply

        Oooops, sorry, that was the wrong video link posted above
        You can delete that link.
        This is the correct you tube video link

    • Bryan 12:03 am on November 25, 2015 Permalink | Reply

      Attempted to share a write-up of my resurrected treadmill, but apparently WordPress didn’t like it… to summarize, my treadmill control panel fritzed out and the dual-555 circuit saved me from having to buy a completely new treadmill (>$1000). My out-of-pocket was well below $100, so the return on that effort was very high. Thanks for sharing your know-how with us DIY kindred spirits…

    • Wesley 1:20 am on January 3, 2016 Permalink | Reply

      Great stuff all of you are doing here. I’ll admit right up front that I don’t have near the knowledge you guys do when it comes to these sorts of things. I’ve been trying for days now to hook this Mc-2100 Rev B up and get it running, but no luck. Not entirely knowing how the pots are hooked up might help as this is the only thing at the moment that I am pretty unsure of. Would one of you mind helping me out with this? I’m needing to get this onto a wood lathe next week so that I can turn some big posts with it. Thanks in advance for any help.

    • Doug 8:46 am on January 3, 2016 Permalink | Reply

      This is the project that I used my Treadmill motor on. It’s a dual action aluminum can crusher

  • schoolie 11:59 pm on February 17, 2013 Permalink | Reply
    Tags: 555 timer, , , ,   

    MC2100 Dashboard Replacement Control Circuit Update 2 

    MC-2100 PWM Controller Circuit v5

    In response to Terry’s comment on my previous MC-2100 post, I got the breadboard circuit hooked back up for some testing. In doing so, I found a couple things missing in my previous schematic. I also may be backing off calling this version of the circuit done. It looks like there may still be a bit to learn :).

    (Read the rest of this post…)

    • Terry 1:25 pm on February 18, 2013 Permalink | Reply

      Interesting that you had made those changes. Unfortunately, I have virtually no test equipment (only an analog multimeter). I don’t even have the MC-2100 board as a friend simply wanted a PWM circuit provided. Anyway to simulate the output I have the base of an NPN transistor attached to the output of the comparator. The emitter attached to ground and collector has a DC motor attached connected to the +12Vdc to somewhat separate the voltage rails between it and the PWM circuit. Adjusting pot R6 as per your circuit does indeed slow down / speed up the DC motor I have. As mentioned, however, I cannot get specific readings. As far as my earlier overheating of the 7805 , all is well now. I had some extra circuitry on my bread board which could have been the issue. My 7805 is quite comfortable to touch.

      I have not tried your new changes to the circuit. Not to speak less about your design (which I do like) but I keep switching between yours and the following to try to get a working solution: http://www.dprg.org/tutorials/2005-11a/index.html.

      I am not sure if I provided you any useful information but I just wanted to let you know where I am at.

      Thank you

      • schoolie 11:44 am on February 19, 2013 Permalink | Reply

        Good to hear you’ve got the overheating sorted. As far as test equipment, there are still ways to get some meaningful data without an oscilloscope. The motor is a good first impression that you’re able to change the duty cycle of a square wave, but doesn’t tell you much else, as you know. Testing on the MC-2100 will tell you if your period is correct, but won’t tell you a value or whether the period is too high or too low.

        Here’s a little tip to help avoid one of the traps I fell into: the indicator LED on the MC-2100 will flash quickly indicating that a signal is received only if the motor is connected across the Motor + and – terminals. This lead to lots of confusion and frustration when testing on the bench without the motor hooked up. I kept thinking my circuit wasn’t working, when it was actually fine. This was before I got the oscilloscope, so I was in the dark as well.

        I tested a make shift method for measuring the signal last night using a piezo buzzer and an android spectrum analyzer app. I’ll try to get the details written up soon.

        Regarding the cicruit on dprg.org, I think I had looked at that earlier. Reviewing it yesterday, it looks like the only way to change the frequency in small steps is by modifying the value of C1 by adding capacitors together in parallel/series, right? You could change R1, but there aren’t many options to choose from when it comes to potentiometers. If I did the math right, you’d need a 0.72uF cap with a 100k pot to get 20Hz. If R1 isn’t exactly 100k, C1 would shift a little. In the circuit I’m using, the frequency is adjusted with a potentiometer (R1), making it a lot easier to fine tune. The part count on mine is a little higher though.

        • Terry 12:16 pm on February 19, 2013 Permalink | Reply

          Excellent. Thanks for the update. It will certainly save me time knowing that the motor needs to be connected to get the proper LED indication. I am definitely interested in the write-up regarding the Android Spectrum Analyzer App.

          Regarding the circuit on DPRG.org. I also noticed it had a set frequency based on R1 and C1. I was thinking of placing a 20k trimpot between pin 3 of the 555 and the R1 pot. I think theoretically this additional trimpot will allow me to adjust the frequency while R1 will allow for the duty cycle to be altered.

          Not to worry though. I still have your design in mind for possible final solution.

          • Terry 2:51 pm on February 19, 2013 Permalink | Reply

            I realize now, with the 20k trimpot included that will most likely affect the outer bounds of the duty cycle that can be attained. We shall see if it will be something that can be lived with.

            • schoolie 9:13 pm on February 19, 2013 Permalink | Reply

              I think you’re right on the trimpot limiting the duty cycle. However, I think it may work if you placed it in between D1 and R1. In that position, it would limit the minimum off time, while still allowing zero on time. This would work better than placing it after R1 because the MC-2100 only accepts 0 to ~85% duty cycle. Driving it over 85% shuts it off, I assume this is a failure mode prevention, wouldn’t want the treadmill taking off if a wire gets shorted high!

              There’s also the max speed calibration pot on the MC-2100. I haven’t messed with it, but I think it should be able to compensate somewhat even if your max duty cycle ends up under 85%.

    • Christopher 10:35 am on March 8, 2013 Permalink | Reply

      Hello, finding this thread very useful. I’ll be building one of these controller boards soon…could someone tell me the id of the two components on the MC2100e rev c board please,they are the two pieces attached to the heat sink on the left, Q5 and D13 I have G4PC40K for Q5 but I can’t identify the diode (I presume?). Many thanks

      • schoolie 7:22 pm on March 8, 2013 Permalink | Reply

        On mine (MC-2100 WA, one of the US versions), the two large components on the left of the heat sink are labeled Q2 and D13. Are these the components you’re asking about? I’ve noted them in the following picture: Q2 and D13 Identified

        Here’s a closeup shot of the two components, showing their labels: Q2 and D13 Closeup

        The components in question on my board are Q2: IRFP250N, and D13: HFA15PB60. They match the reverse engineered schematic I’ve posted previously. They’re the switching transistor and flywheel diode for the main motor current.

        The MC2100e may be different, I’m curious to see if your components match this.

    • Terry 7:13 pm on April 13, 2013 Permalink | Reply

      I am still working on this. I managed to obtain an oscilloscope to check my circuit. I switched to a different circuit:


      simply because I had the parts for it.

      I added a 7805 voltage regulator to power the above circuit since the specs on the MC-2100 states there is 9VDC on the red wire and a 5VDC signal is required on the pulse (blue) wire. On the test bench with a 12VDC power supply the output signal looks good frequency-wise. When attached to the MC-2100 with the cable that came with it I can get the on-board LED to blink but the motor is erratic. I found the 7805 to also get very hot. While on the test bench the 7805 does not get hot at all!!! Removing the cable and using some of my own jumpers instead, the results were better and the 7805 was much cooler. Testing the original cable for continuity shows good so this does not make sense.

      Attaching the scope on the ‘pulse’ line at the board shows a decent signal other than the fact that the highs are around 3VDC. Which led me to believe that it was too low to allow the MC-2100 to function properly. I am thinking that the MC-2100 is not receiving a high enough voltage. So, since the above circuit did not include a voltage regulator I decided to bypass it and apply the full voltage from the red wire of the MC-2100. The motor appeared to work much better. I thought I had found my solution until I started to smell smoke.

      After quickly disconnecting the cable, looks like I burnt out a 22 ohm SMD at the connector’s ‘pulse’ signal. I figure I can replace with a regular resistor of same value. Hopefully, that will be the extent of what has burnt out.

      Just wondering if you noticed or had issues due to the signal voltage level as well.

    • Terry 9:35 am on April 14, 2013 Permalink | Reply

      In my further research I found the following:


      which is stated to be for the REV B. board. Which happens to be the board I have. What luck!!! And it confirms the 22 ohm resistor at the ‘pulse’ (blue) wire. A lot of other useful comments on the schematic as well that other people might find handy.


    • schoolie 10:20 pm on April 14, 2013 Permalink | Reply

      Regarding the low voltage measured at the MC-2100 control input, I noticed that as well. Everything I checked seemed OK, so I’ve left it alone. Upping the voltage to try to overcome the voltage drop burned the resistor out as you suspected.

      I’m as stumped as you are on the regulator overheating.

      I wonder if your inconsistent operation when plugged in is due to the noise from the motor signal I described in the post above. Putting a capacitor from ground to the wiper on the potentiometers may help, but I haven’t studied your schematic well enough to say for sure. I’d put the scope on the output when you turn the motor on. Watch for the signal to break up when the motor starts turning. If it’s interference from the motor signal, it’ll be at a much higher frequency than the control signal (60 usec period).

      Hope you didn’t look too far for the schematic, I had it posted here, lol 🙂

      • Terry 10:42 pm on April 14, 2013 Permalink | Reply

        I managed to get some more testing done today. With a little research I found that placing a 100uF on the input of the 7805 improved the voltage level on the output. A 0.01 uF on the 7805 output really cleaned up the 5V rail and the signal. This also really ended up raising the signal highs to 5V. Once I fix up the 22 ohm resistor on the MC-2100 I am theorizing that the motor will work much better.

        I probably saw your copy of the MC-2100 schematic when I first saw your blog months ago because I had a printout but just forgot where I got it. Didn’t think to check here again, but no worries it didn’t take me long to find it. The nice thing is that it shows the external PWM circuit is isolated from the rest of the MC-2100 via the optocoupler. An additional resistor on the PWM output to the MC-2100 may be a good idea to limit current through the 22 ohm and optocoupler.

    • Terry 10:41 am on April 16, 2013 Permalink | Reply

      Well, interesting, very interesting.

      I write this to potentially assist anyone else trying to get the MC-2100 working and maybe offer a different perspective. Not to take away from this original blog because it has certainly helped me greatly.

      If you have read any of my previous posts, I managed to burn out a 22 ohm resistor. Well, I have replaced that resistor and did some testing again. With the scope attached I found the signal from my circuit greatly affected when I attached it to the MC-2100. With the PWM circuit attached I paid close attention to any smoke or overheating. I think now that the output of the circuit I am using is really not designed for direct input to the MC-2100… First is the voltage I used which blew the 22 ohm resistor so I definitely advise the addition of the 7805 voltage regulator. And now as I pay closer attention to it, I find that the optocoupler is also getting very warm. Although I haven’t yet found max ratings for the anode-to-cathode of the optocoupler it appears that I am exceeding the maximum current rating. Reviewing this document: http://preher-tech.com/documents/optoisolators suggests that the forward resistance on a good optocoupler which matches the device on the board (F817), there should be around 20 ohms. In conjunction with the external 22 ohm that means a direct 5V signal would set the current at 125 mA…seems a little much and may also explain why my 7805 voltage regulator gets warm only when the MC-2100 ‘pulse’ (blue) wire is connected to the PWM circuit. I will be removing the optocoupler to properly test it to see if it is still good and I have to rethink the link between my circuit and the MC-2100. Maybe adding an additional resistor in series would be a good start to limit the current through the optocoupler.


      • schoolie 8:10 am on April 17, 2013 Permalink | Reply


        You’re correct on the need for an additional resistor. I hadn’t noticed it previously, but now that you’ve brought it up, it’s definitely necessary.

        The LED in the optocoupler (like all LEDs) has a constant voltage drop regardless of current (unlike a resistor). According to this datasheet, the forward voltage drop of the LED in the F817 optocoupler (U1 on the schematic) is 1.2V. This leaves 3.8V to be dropped by the resistor(s) in series with it when 5V is applied. With only the 22ohm R2 resistor, that results in a current of 172mA, much higher than U1’s 50mA max rating. It’s not continuous, so it doesn’t cause instant failure, but it’s definitely not good.

        I looked at the circuit board from the treadmill’s dash panel, and sure enough there’s a 240ohm resistor in series with the control signal output. This brings the total resistance to 262ohms, and the current through the optocoupler to 12mA. Much better!

        With that understood, it’s likely ok to drive the circuit without the regulator, just using a larger series resistor to compensate for the increased voltage. For example, assuming the MC-2100 outputs 9v, the resistor needs to drop 7.8V. A 620ohm + 22ohm resistor pair would result in the same 12mA current through the optocoupler .

        I haven’t tested this at all, but I’m confident that it’s the right direction to head.

        Good catch!!

    • Terry 7:52 pm on April 20, 2013 Permalink | Reply


      I added in a 680 ohm resistor in series on the output of my circuit into the MC-2100. Works well and no more overheating. And with the addition of this resistor I was able to remove the voltage regulator and its associated capacitors to increase much needed realty on my prototype board. Thanks for the suggestion.

      I am running into a problem now which I didn’t see in any of your blog posts and I was wondering if you encountered a similar issue. This is the situation:

      1) With all pieces hooked up (PWM, MC-2100 and motor) and powered up, the frequency on the PWM is adjusted until the MC-2100 LED is blinking and the motor runs.
      2) The motor is left to run for a 1/2 hour to check for any overheating issues.
      3) Power is switched off which of course turns everything off.
      4) Power is switched back on.

      Now, at this point since the motor was running and the MC-2100 LED was blinking just before power was removed, it is expected that everything would just start up again when power was turned on again. However, it does not. The LED does not blink and the motor does not run until the trimpot on the PWM circuit is once again adjusted which gets everything going again. It is as if the MC-2100 needs to be manually reset until it can once again recognize the required frequency. I was thinking that once the frequency on the PWM circuit was set I wouldn’t need to adjust the trimpot ever again.

      Any suggestions or ideas from your testing?

      • Terry 9:30 am on April 21, 2013 Permalink | Reply

        Turns out the MC-2100 has a safety that requires ‘user input’ from the treadmill before it starts, to be sure it is not starting at full speed. Adding in a switch gets around this. All is good now.

        • schoolie 8:39 am on April 22, 2013 Permalink | Reply

          Yep. When the MC-2100 powers up, it doesn’t act on the control input until it sees a zero speed signal. I’m curious, what are you using the controller for? Sounds like a fixed speed application?

          • Terry 8:45 am on April 22, 2013 Permalink | Reply

            Actually it is not even mine but a friends. He just didn’t have a way to control it. He is attaching the whole thing to a lathe.

    • Raymond 8:54 pm on May 13, 2013 Permalink | Reply

      Hi Guys, I plan on building the PWM that you guys worked out. I was wondering if you could put together a complete parts list. If you could I would appreciate it

      • Terry 9:43 am on May 14, 2013 Permalink | Reply

        Hi Raymond,

        My final circuit differs from schoolie’s simply because I didn’t have all the parts for his design. I believe you can find everything you need here about schoolie’s design but I am putting a full document together (start to finish) of all the work I have done as well to help others whether they want to use the same circuit or not. I should have that completed over the following weekend. With schoolie’s permission maybe I can post that document here as well for you to obtain.


        • schoolie 10:20 am on May 14, 2013 Permalink | Reply

          Raymond, I’ve got a few changes that need to be made to the circuit to simplify and correct the output current. I’ve built the circuit, but haven’t had time to test it. Once I’m happy with it, I’ll post up the parts list and schematic.

          Terry, I’d love to have your solution documented as well. Whenever you get around to it, write something up and I’ll post it here for future reference.


          • Raymond 2:17 pm on May 14, 2013 Permalink | Reply

            Terry & schoolie

            Sounds great I’ll be patient & await the completion of the PWM project.
            Just to let you guys know I am so green at this Electronics stuff, but am learning allot.
            I think I should not have a problem putting one together.
            I wish I had the knowledge that you guys do.

            Thanks Again

          • Terry 9:44 pm on May 18, 2013 Permalink | Reply

            schoolie, I couldn’t find a way to upload my document (PDF) here. Maybe only you can do it. Let me know.

            • schoolie 2:58 pm on May 20, 2013 Permalink | Reply

              If you email it to me, I’ll include it in my next post. I think I’ve got the final version of my circuit ready to go as well. My address is brian(dot)p(dot)schoolcraft(at)gmail(dot)com


            • Amir 3:59 pm on June 28, 2015 Permalink | Reply

              Hey Terry & Schoolie,

              I’m having some weird issues with the MC 2100 control board, if you don’t mind me throwing a few questions at you guys I’d greatly appreciate it!


  • schoolie 11:38 am on February 12, 2013 Permalink | Reply
    Tags: 555 timer, , , ,   

    MC2100 Dashboard Replacement Control Circuit Update 

    This is another quick update on the MC-2100 PWM controller project. I’ve tweaked the schematic a bit to put the 5v regulator at the beginning of the circuit, which I think is a better configuration. This circuit is currently on a breadboard, and worked great until the connections in the breadboard started wearing out (around a month of occasional use, including our paintball gun build day). Here’s the latest (and probably final) revision:

    MC-2100 PWM Controller Circuit v4

    When I started this project, I wanted to get this circuit working without a microcontroller for the sake of education and simplicity. At this point, I’m comfortable with calling that goal achieved. Now it’s time to move on to more features, like a tachometer and possibly closed loop control!

    My current direction with this project is to develop a combined tachometer/speed control for the MC-2100 and my lathe. I plan to use an arduino to measure speed, display the speed via 4 digit 7 Segment modules (salvaged from the treadmill control panel), and send the PWM signal to the MC-2100. At this point, Joe and I have a working version of the code put together, and the circuit prototyped on a breadboard. I’ll update with progress once we’ve got something more final.

    • Terry 11:03 am on February 17, 2013 Permalink | Reply

      I am using your latest circuit to connect to an MC-2100 board. Did you find the 7805 voltage regulator to get extremely hot? I am finding the current on the output of the 7805 to be in excess of 250ma… With a 7V drop (12 – 5) that works to a minimum of 1.75W to dissipate at the regulator.

    • ajcharles 5:43 pm on April 3, 2014 Permalink | Reply

      I tried the circuit it work well except I haf to make some modification tp it. I had problems keeping the speed constant so I hsd to add a diode frpm output to controller input. Also the frequency of my controller was 57.7

  • schoolie 12:15 pm on November 12, 2012 Permalink | Reply
    Tags: 555 timer, , , , ,   

    MC2100 PWM Controller Schematic 

    Just a quick update. I haven’t finished the permanent driver board, but thought I’d upload a better version of the schematic. I’m currently trying to decide if I’ve messed up the MC-2100, or if my soldering just sucks. At this point, I’m getting the motor to come on, but not consistently like it was with my breadboarded circuit. The indicator LED will flash 5 or six times, and the motor starts turning, then the LED goes back solid like it’s not getting signal, and the motor slows back down. I’ve had a couple of occasions where the motor will run up to full speed, so it’s at least close. I can at least confirm that this circuit worked on the breadboard, as shown in the previous post.

    Schematic of PWM Driver

    I also wanted to post a few of the relevant files I’ve found pertaining to the MC2100.

    Here’s the document that describes how the controller is interfaced with the treadmill, and the function of each pin of HD2 on the MC2100.  This is essentially the same file that James linked to in the comments on my previous post.

    The following file has been extremely helpful in troubleshooting the MC2100 itself as I’ve messed it up along the way.  The file was provided by a member of the Home Shop Machinist forums in this thread.

    Reverse Engineered Schematic


    Check out the rest of the MC-2100 Project Here

    • Darrel 12:01 pm on February 6, 2013 Permalink | Reply

      You might have opened my eyes now with this cheers

      • schoolie 12:06 pm on February 6, 2013 Permalink | Reply

        Great. Hopefully it’s helpful. Let me know if I can clear anything up!

    • chris 1:40 pm on March 30, 2014 Permalink | Reply

      hey, i’m trying to do the same thing. wondered if i could ask you a couple questions… chris

    • Ian Grant 11:57 am on April 1, 2014 Permalink | Reply

      Very impressed by your expertise and wondered if you’d be kind enough to help me.
      I have a treadmill with the MC2100.
      The belt motor is definitely OK and I think the MC2100 is ok too.
      It seems that the console is not sending the right signals.
      Occasionally I will get it to run and the led blinks as it should.
      The only functionality I’m trying to achieve is control of the motor and even 0-5mph would be OK.
      What inputs to HD2 are required to make this happen?
      Any help would be hugely appreciated – the wife is desperate to get back on her treadmill and I need the brownie points!
      Thank you

      • schoolie 9:23 am on April 2, 2014 Permalink | Reply

        Hi Ian, the best simple circuit I’ve come up with to replace the console is in this post. It uses a 555 timer and a comparator to generate a ~50ms period variable duty cycle 5v square wave. The HD2 connections are shown on the schematic. The circuit uses a potentiometer as the user input.

        Let me know if you have any questions, or if the schematic doesn’t make sense to you.


        • Ian Grant 8:42 pm on April 3, 2014 Permalink | Reply

          Hi Brian,
          Many thanks for your reply – much appreciated.
          Prior to your reply, I’d drilled down a bit deeper and came across Terry’s circuit which I’ve bought the bits for and have started to build, but maybe I should have gone for the one you suggested – or maybe either will work Ok.
          I’m very rusty on all this stuff. I’m a 65yr old Brit currently in America – where are you located out of interest?
          I’m immensely grateful for this blog (without which I wouldn’t have been able to get started!) and for the input of you fine folks

    • schoolie 10:38 pm on April 3, 2014 Permalink | Reply

      Terry’s circuit should work fine as well, they’re just two different ways to accomplish the same basic goal. I’m in central Indiana. Let me know if you run into any problems asking the way. It’s cool to see people using this stuff 🙂


  • schoolie 10:34 pm on September 26, 2012 Permalink | Reply
    Tags: 555 timer, , , , ,   

    PWM Board for MC-2100 Treadmill Motor Controller 

    Free treadmills from Craigslist are a great source of DC motors and motor controllers for machine tools.  A quick search will yield several examples of people repurposing these motors and drive for drill presses, lathes, and various other equipment.

    From what I’ve seen, the MC-60 type controller is by far the most common in low end treadmills (the type you typically can get for free).  Three out of the four treadmills that have passed through my garage have had the same MC-60 controller, and nearly identical permanent magnet DC motors.  This controller is relatively easily repuroposed as a machine tool drive, as the input is a simple voltage divider circuit driven by a potentiometer.  Just take the pot off the treadmill’s dash, mount it to your bench, and you’re up and running.

    The MC-2100 proved to be a bit more complicated.  My first clue was the all digital dash on the treadmill it came out of.  A quick google concluded that the MC-2100 required a 5v PWM signal with ~50ms period.  I found a good reference circuit on the All About Circuits forum (Link):

    This circuit has two stages.  The first is an astable 555 vibrator.  Tapping off the capacitor charge pin (Pin 6 on the 555) results in a sawtooth output, with the frequency set by R1, R2, and C.  This sawtooth is then fed into a LM393 voltage comparator to convert the sawtooth wave into a square wave.

    Here’s my final circuit sketch:

    And a quick first test video:

    In my opinion, it was worth the effort to figure out because the MC-2100 is a high frequency PWM controller, as opposed to the MC-60 which is an SCR based controller that operates at line frequency.  This results in a much quieter motor.  Also, based on a couple quick test cuts, the MC-2100 seems to have a higher current capacity.

    Check out the rest of the MC-2100 Project Here

    • James 2:17 am on October 22, 2012 Permalink | Reply

      I have the same treadmill motor controller with a motor that I’m planning on using on a metal lathe (I recently had to sell my old Atlas 618 and I’m planning to buy a smaller taig lathe and want to have the motor & controller resolved before I buy it). Your hand drawn schematic is a little difficult to read in some parts and I was wondering if you could provide a higher resolution image. I have some basic electronics experience and a few 555 timers laying around, though I certainly would not be able to engineer this circuit on my own. If you don’t mind too much, I may ask for some advice along the way as well if I run into any problems.

      • schoolie 8:44 am on October 22, 2012 Permalink | Reply

        I’m working on getting this design soldered onto protoboard, and making a few tweaks along the way. I’ll get a better schematic put up once I get everything checked out and verifed working. I wouldn’t mind answering a few questions along the way either.

        • James 1:35 pm on October 22, 2012 Permalink | Reply

          I’ll stay tuned. Thanks.

        • James 2:55 pm on October 25, 2012 Permalink | Reply

          I had a few old Arduino boards laying around. I relearned how to program them and came up with this simple code (pasted below for anyone looking to do this in the future) to run the motor off of a trim pot. It works perfectly. I had read that the controller likes a frequency of 51ms, mine likes 49 or 50ms, which is what I used for my code. I had also read that the maximum duty cycle is 85% on, which is why I scaled the pot value from 0 to 42.

          Necessary parts:
          1 – Potentiometer
          1 – Arduino Board (around $30)

          This code creates a PWM signal with 0-85% duty cycle and 50ms frequency on the MC 2100 treadmill motor controller

          int ledPin = 11; //this is the PWM signal out
          int pot = A0; //Potentiometer (connected from 5v+, A0, Grnd)
          int potValue = 0; //Tells Arduino there will be a # named potValue

          void setup()
          pinMode(ledPin, OUTPUT); //tells arduino pin 11 is output
          Serial.begin(9600); //arduino counts. only necessary if you want to pint (below)

          void loop() //the following cycle will repeat every 50ms
          potValue = analogRead(pot); //reads potentiometer value
          potValue = map(potValue,0,1023,0,42); //scales potValue to 0-42 (85% duty)
          digitalWrite(ledPin, HIGH); //turn duty on
          delay(potValue); //time duty is on
          digitalWrite(ledPin, LOW); //turn duty off
          delay(50 – potValue); //time duty is off (50 – on time)
          Serial.println(potValue); //not necessary. shows duty on computer
          The analog out pin (11, named ledPin) is connected to the blue wire, and the black wire is connected to the arduino’s ground. The arduino is powered by the red and black wires from the controller. I also found this wiring diagram of the controller:

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