Changing the Potentiometer in an SCR Voltage Controller Treadmill Motor Controller Power supply
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- čas přidán 3. 08. 2022
- In order to use an SCR voltage controller to control a treadmill motor usually the potentiometer that comes with the SCR needs to be replaced with a smaller one. Using two smaller ones of different sizes gives you a course and fine speed control. This video shows you how to determine what size potentiometer you need and if you so choose, how to run two of them for fine speed control.
Affiliate links to items in this video:
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10K potentiometer amzn.to/3QAtiES
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Excellent video! Very informative. Thank you for sharing this. I have recommended your channel to many people. Hope it helps you out. Because all the information you have provided. Has helped me out a ton.
Much appreciated!
Woldn't have found you searching for treadmill stuff on CZcams, Googled and came to get your excellent info. Planning on repurposing a treadmill into flatbed drum sander. Just finished disassebling it. Thanks for you sharing your knowledge.
Glad to help! Unfortunately there are so many videos on CZcams, a lot of them not very good, that finding my channel is like trying to find a needle in a massive stack of needles. I have been at this for several years now and tons of people have made comments similar to yours. Don't hesitate to reach out if I can be of any further assistance.
Holy cow! I've been searching for just this answer and explanation. Thank you!
Glad it was helpful!
I dismantled 3 treadmills to reclaim the dc motors a couple of years ago. I have been searching for a clear explanation of either how to use the boards from the treadmills or an SCR controller. Others seem to treat lightly or skip over the most important aspects of this solution.
You have provided a clear and thorough explanation and I’m grateful for it. 2x72 grinder project can proceed now….
Which controller boards did your treadmills come with?
@@dazecars I’m out of town until Monday and it’s too long ago to have a clear memory. I’ll look at them when I return and get back with you. Thanks
@@dazecars I have a MC-2100 Rev B and a MC-2100LS-30 Rev and another board labeled MCC1H ( that one has a transformer or choke on the board with 2 plastic connectors with 2 pins each) I have photos of all of this. I have 2 new SCR controllers 10,000 watts 220v which look like the ones you recommend. I also have 2 bridge rectifiers labeled KBPC5010 and potentiometers labeled B200K 17mm and B10K,.
Motors are 1.75 hp cont duty at 100 VDC and .5 hp cont duty at 108vdc, another 2.5 cont duty but couldn’t read the vdc req’d because of access to it. The small .5 hp was on some type of stepper or incline type TM but was the primary motor. I also salvaged smaller “stepper” or lifting motors I think 2 or 3 of them.
@@Grumpyneanderthal Sounds like you hve lots of options. Im not familiar with the MCC1H. The component attached to the board would be a transformer not a choke. I have used that same rectifier you have and they are prone to burning out I would recomend getting a better one if you decide to go with the SCR setup. amzn.to/3Gk4InH
@@dazecars thanks. Bridge rectifier link at Amazon is currently not available but I ordered 2 direct from Baomain w/ free shipping.
I’ll go through the process you described to determine which potentiometers are required.
This is a great. It was the missing link that I’ve been looking for!!!
Glad it helped. Let me know if you come up with any other “missing pieces” I can help with.
Very Informative! Editing skills are killer.👍
Thanks! 👍
Thanks for an easy to understand and follow explanation
Glad it was helpful!
Thanks for your help and all the great videos
My pleasure
Great video. I run several machines on treadmill motors. thanks
Glad you liked it!!
Thankyou so much and you are the man 👍👍👍
No problem 👍
Very good article
thanks
Super good stuff 🎉
Thank you!!
Excellent
Thanks
Thank you 🙏 🤔👍👍
No problem 👍
nice one thanks
You are welcome
Great presentation, Thank you! Could you do a short video on how to wind a inductor? I’m wondering how many windings are required. Thanks
its just 7 wraps with each lead
Good idea ...thank you for that .150 k omh is good ..but the hall senssor more beter then potentinmeter ...it's just using a ebike throttel ...thank you
Thanks for sharing
For once someone actually read the needed potentiometer value to see what size was needed. However, there really is another way to make this work very precisely. Take a resister and parallel it across the center wiper lead and which ever side lead you are using. And then you can get a simple resistor to make the pot the exact value you want. Just remember parallel resistors are lower in resistance value then the lower value of either of them. Solve for parallel resistance to make the pot the resistance you need... If you have a 100k ohm pot and need a 50k ohm pot, use a resistor in parallel to make the pot read 50k ohm. A 100k ohm resister will come really close... Try it... Thumbs Up!
Great advice and even better description on how to do it. I am familiar with the concept of parallel resistors. The thing I don’t like when a fixed resistor is paralleled with a potentiometer is the potentiometer is no longer linear and the non linear change in resistance is the worst at max resistance. on an SCR max resistance is at slowest speeds and that IMHO is where you need the finest speed control. It’s not that big of and issue but just not my preference.
@@dazecars Well the only true idea is to buy a pot as close to what you need in a linear scale, even better idea is a multiturn pot. That way you can dial in the exact RPM you want... JMHO
@@garymucher4082 I hope you didn't think I was being argumentative, your info was great. I was just expressing my concern with using a resistor to size a pot for this application. As to the multi turn pot thats a good option and would totally work. It is similar to the two potentiometer system I run.
@@dazecars Not at all. I also understand your reasoning. Good video and explanation of why you need to change the initial pot that comes with those SCR controllers... And that is also the reason I have a few meters. A very good Simpson 260 series analog meter for just watching the needle sweep and lots of digital Fluke meters to read everything else. Thumbs Up!
@@garymucher4082 no fancy Flukes for me 😁 I use a simple 20 year old Radio Shack meter with broken cover. I wish I could find another one. They went to an autoranging unit after the one I have and it pales in comparison to mine.
hi fantastic videos. thanks for the info. just one question .when using the two pots in series, do I use the little white plug on the 500k pot. assuming so do I connect it with the red wire coming in to the first pot ,then the black wire to the second pot. to go back to the scr .then plug the white plug from 500k pot (without 500k pot connected) back into the pcb board on the scr. Hope this makes sense, Thanks for your advice, Dave .
yes you do still use the white plug and wires from the SCR. As far as which wire goes where it doesn't matter. a resistor limits flow in either direction so there is no problem connecting the black to one and the red to the other or doing the opposite. That is of course assuming the potentiometers are correctly wired together in such a way that they both adjust the same direction.
Thanks for the video! You included some 0:02 more information in one of your other videos about adding a resistor to one of the pots and o can’t seem to find it, I have watched all your videos so my playlist isn’t helping either. I want to run two pots but was thinking you added a resistor??
The extra resistor in series is only if you need the max motor RPM to be less than the potential RPM with you motor/power supply combo. I did that on my bandsaw because so as to not drive the blade any faster than it was from the factory at "top" speed
Adding a fixed resistor on the “return line” of potentiometer , would that then limit the high end speed??
Also, having a large 2,000 ufd 300 volt capacitor across motor leads help brush arcing or motor life, or be instead of a choke? Thank you, learning a lot watching ur video’s
Yes having a correctly sized fixed resistor in series with the potentiometer will limit top speed. There is however no "return line", resistors are not directional and electricity can flow either direction. If the resister is not correctly sized and is too big it will create a dead spot at the bottom. As to the capacitor this is one of the most common comments. People ask or comment all the time about adding a capacitor. I did run one for a wile. It came directly from a treadmill board. I removed it because it caused surging under a load and there was no visual difference in brush sparking.
Not sure yet what potentiometer was put in mine. But it starts my shopsmith bandsaw conversion, right away. I have the push button one in it, bogs bad. The one you recommend does not bog as much, but has to be turned up to get the cut done. But then turned back down after the load is removed, or it over revs the bandsaw and blows off the tires. My thought, 2 potentiometers, selector switch between them. So I can have a no load speed and with load settings. ??
Video On my Twitch!
Bogging should have nothing to do with the potentiometer. Three things cause bogging... well 2 and 1/2. If your motor is too small that will cause bogging. If it is a small motor you need it to be geared properly to help eliminate the bogging (that is the half) but even a bigger motor would probably need some gearing. I have a huge motor on my lathe and I have it geared at 3.5:1 And then the big one is using a quality SCR. Are you using the same one I am or one of the cheaper ones that are in all the other videos on the internet? Keep in mind also it could be any combination of the three. For optimal results you need a big motor a good SCR and some gearing to maximize function at lower RPMS.
Using the SCR you recommend.
It starts soon as I turn up. Maybe 1/16 knob turn.
I think gearing is the issue, it will rev to 5200 now, can't really use over 1800 strong. Will look for some pulleys to adjust. Measure mine tomorrow. Video on my channel of mine running now. Thanks for the info.
@@FrugalFixerSpike I would take the max motor RPM and divide by max desired RPM and then round down to the closest gear ratio you can get to that number. I would round down so you are running the motor at max as little as possible. Most motors will last a lot longer if they spend their time at 85% of max or less.
I see you also have AC going through an inductor and what appears to be a fuse or circuit breaker and DC output going through some sort of choke. Can you give me more details on what you used for these.
Take a peek at this video. If after watching it you still have questions, please don't hesitate to ask. czcams.com/video/SjEgKH_MGFE/video.html
If the potentiometer was in-installed from the body, which two terminals would you measure Ohms between?
depends. The middle one is always one of them but it could be either of the outside ones one is high and the other is low and which one is which depends on the manufacturer.
Great video, have you done one on the wiring you were using for this video, reason I asked is I wanted to know how the dc & ac choke was wired etc cheers
Yes I have, watch the SCR hookup video I linked in this video.
Awesome thank you so much , this will help immensely 👍🏼🙏
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Can the scr controller set up power a 4ph motor pulling say 250lbs ( just like a treadmill)
a treadmill isn't "pulling" anywhere near 250 pounds as the movement has very little to do with the person on the belt. what are the amp requirements of the motor. What kind of RPMS are you wanting to run this at? The only way you will have a shot of getting it to work is by gearing it way down.
I changed the pot in my 220v 4000A SCR from 500k to 150k and the treadmill was running smoothly but still to fast, should I try using 100k pot. I can get the motor to run slow but it starts to surge and slip as if it has little power.
a 4000W SCR is too small and you will likely burn it up eventually. The minimum speed on an SCR setup has little to do with the potentiometer. As long as it does not come on with the pot at the slowest setting then changing the pot to 100 will only make it faster. Sounds like you need to gear it for more power and slower speeds.
hi thanks for your videos, please can you tell me if treadmill motors are reasonably good for accuracy , one guy on youtube seems to pull them apart and machine end caps and improve them. this sounds like a pain to me. i like the SCR idea , i,m in the uk on 240volt, i have a bodine motor which is on 115v dc 7500 rpm to 8500 rpm . i would like to use this motor and be able to change at will to other motors. I know i,m rambling on a bit, but any advice would be great cheers john
Define "reasonably good for accuracy"? I use them on my metal lathe, my mill and my bandsaw without issues. After gearing I have speed adjustment on my lathe of 50-1500 RPMs Depending on what you are putting it on that motor may not be up to the task. Motors with that RPM range are usually lower torque. Spend some time on my channel, there is lots of good info there. Also if you give me more details about your project I can provide better insight. Start with this video but look through my other offerings czcams.com/video/A_zBGJkhBAc/video.html
Another options is to use a multi-turn potentiometer but they are more expensive.
Thanks for sharing that option it is a good thing for people to know. It’s not something I like however for two reasons one like you mentioned the added cost, and two the amount of turning that you have to do if you’re going a significant number of RPMs. In other words with my current set up if I’ve got an increase it by 500 RPMs I can go right to the course potentiometer and crank it up if I was using a multi turn potentiometer I would have to turn it quite a bit to get that same jump. for me the two potentiometer system is more efficient when it comes to time when making adjustments. Not that that really matters I’m not a production shop so saving a few seconds here or there doesn’t get me much. 😁
Great video, I have an upcoming project to convert my drill press and now I understand how to select the correct potentiometer(s). What impact would a fixed resistor in series with the pot have?
you could add a parallel resistor of the correct value to "size" the potentiometer, my concern would be that when putting a resistor in parallel to a potentiometer the knob adjustment of the potentiometer is no longer linear. the further the potentiometer resistance gets from the fixed resistance the less change. That means the knob will not create a consistent speed adjustment. It will get finer as the potentiometer resistance decreases but the SCR speed will be going up and most often finer control is more important at lower speeds. That is why to me the best solution is two pots. You can get the exact desired starting ohmage, add fine speed control while keeping the adjustments linear.
@@dazecars Thanks, won't get to my project for a few weeks but I'll start by figuring out the second pot I need and get it on order. Lots of them to chose from on Amazon, do I need to be concerned about the power rating or maximum amps when selecting?
@@dazecars Actually my question was about a resistor in series. I think you answered my question on your web site. If I understand it correctly the series resistor limits max speed but doesn't help expand the control range of the pot.
@@douggarson50 No it's just a signal current so most should work.
@@douggarson50 you said series and some how I read parallel. Sorry for the confusion on my part.
Was wondering if you could help me by telling what scr and Potentiometer i need for this application
I have a 1.5 hp cont. Duty @ 95 vdc
And it is 21.4amps
I want to be able to slow it down to a 50rpm on the low side and 100 120 rpm on the high side roughly and that is a guess on rpms
It is for a drum tumbler
Plz help lol
Use the SCR that I have linked, use the technique in this video to determine potentiometer size for your system and then you will need to gear it down a ton to get the RPMS you are after. Likely in the 10:1 neighborhood. Also those specs sound like the smaller motor in most cheap treadmills so it may not be up to the task of a tumbler.
I found a Dork motor speed controller from a previous project and would like to know if you think it will be ok to uses for my tumbler
Working v 10v -50v
Control power 0.01-3000w
Max rated current 60A
And the motor I have is a 21.4amp 1.5hp cont @ 95 vdc
I know you said that I had a cheap treadmill motor lol but I still didn't want to burn it up
Hopefully I gave you enough info
And thankyou fornyour time
Your motor might be a good one but based on the specs you provided I am guessing it is one of the cheap ones. That power supply should work, but you will still need to gear that motor WAY down
With that set up what is the maximum load the scr can carry
its good for 10000 watts max so assuming max 110V (going to actually be less than that as some voltage is lost in the SCR and rectifier) that would be 90 amps. A * V = W Now a good rule of thumb is 1/2-2/3 max so that would be 45-60 amps BUT you are limited by the max amps coming out of the wall.
Try adding 2M ohms resistor parallel to potentiometer it will be equal to almost 140k ohms.
That is a great point, my concern would be that when putting a resistor in parallel to a potentiometer the change of the potentiometer is no longer linear. the further the potentiometer resistance gets from the fixed resistance the less change. That means the knob will not create a consistent speed adjustment. It will get finer as the potentiometer resistance decreases but the SCR speed will be going up and most often finer control is more important at lower speeds. That is why to me the best solution is two pots. You can get the exact desired starting ohmage, add fine speed control while keeping the adjustments linear.
Why didn't you use a 110v input SCR to 90v dc output and not have to worry about the rectifier? Just curious.
the SCR is AC with AC in AC out. The rectifier converts it to DC
I have used this method to control a treadmill motor on my lathe and it works fine. What I don't understand is that I get no readings on my multimeter coming off the bridge rectifier. What's going on? Thanks for your help.
It has to do with the way the SCR works, it requires a load. If you hook it up to a motor and turn it on you should be able to get a reading and get the volts to change as you turn the knob.
@@dazecars Thanks. I'll give that a try.
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Pretty good My friend I have a 130v dc motor from treadmill the question is wats the capacity from Transformer are using in that proyect ? Hope u understand My poor English ,thanks very much
I am not exactly sure what you are asking but I will try to answer what I think your asking. The SCR is 110-220V AC and 10,000 watts BUT you will never get more than what you put in. In other words if you plug it into 110 you will get slightly less than 110V at max, and then less than that as you turn down the speed.
@@dazecars thanks very much thats correct ,i'm sorry for My English not good i saw in Your video also are using a Transformer you says something about choke .
@@elmexicanitonieto6475 a choke and a transformer look the same but they are different. czcams.com/video/WRT_Ri18eLY/video.html
Could you use a 20K resister to make up for the difference in the 120K Potentiometer to give you the 140K that is needed?
Yes you could but it will limit the max RPM put out by the motor.
Thank you Sir. @@dazecars
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why can't you use a regular 120volt Dimmer Switch for lights from the hardware store instead of that SCR. Wouldn't it act as both the on/off switch and the "potentiometer" to the bridge rectifier???
It can't andle the amp draw of the motor and if it could it would produce a lot of heat.
Thanks for reply. So FYI, I went on Rona"s site, local hardware here, and they had a Pair of 120v 15 Amp rated Dimmers on for $27 Canucklebucks. You can also Program the Slider to a MIN. and Max range, which I thought is good to avoid over Volting the motor. My motor is a small one...TruPower, Leeson Electric Corp. made in China. Rated at 96 Volts, 14 Amps, 5120 RPM and is 1.5 HP. Using your formula I think thats 1.53 FT/LBS of Torque. Planning to use it as a Sanding station so I don't really need too much power or amps. I don't think LOL...we'll see. Enjoy your video's and learned enough to get me into trouble .. :-)) BTW I bought one of those SCR's you mentioned but had to returrn it, the Potentiometer was malfunctioning you could just touch the side of the Knob and it would jump 8 12 Volts either up or down from what it was set at..
I look forward to seeing how this all works out please keep me informed. A couple of things to be carful of. First most electronics like power supplies are rated in in max amps not continuous amps. Not sure if that applies to the dimmer switch. Second I am not sure how the dimmer cuts down the power. If it just cuts volts than no problem that will only modify the speed but if it also cuts amps you will lose torque. Anyway just a couple of things to keep in mind @@Erik-6262
How do you remove the knob on a potentiometer ?
They are all a slight press fit but before you start pulling on it look for a setscrew as some also have those.
does it make sense just to replace it with a 5 watts resistor
then you will only get one constant voltage out of it
@@dazecars ok, thanks.
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You probably get asked this alot and may already have the answer posted somewhere but ima ask anyway. What size dc choke are you using for these projects with treadmill motors?
Not being an electrical engineer I do not have any specifis I could provide in trying to get one, what I can do however is offer you some guidelines. First of all bigger is better. I have several motor chokes ranging from the size of a tennis ball to the size of a soft ball and the bigger they are the better they work. Second the wire for the choke needs to be a minimum of 16 awg. If the wire is not that big or better it will not have the amperage capacity to allow the motor to work properly . Third they are not available on Amazon at least not inexpensively, there are a few privet sellers on Amazon selling used parts for big bucks but the available chokes on amazon are too small because they are not designed for a motor even though they look correct in the picture in the picture they are way too small. The choke in most of my videos is part number 130993. Instead of getting one new I would get a used one. A lot of treadmills come with a choke. Go to eBay and search “treadmill motor choke” BUT know that most people on eBay don’t know what they have and the word “transformer" will also appear in most listings. Problem is a choke and a transformer look almost identical so some listings are for transformers and some are fore chokes because the sellers think they are interchangeable. They are not. They would only be interchangeable if you modify a transformer to work as a choke. (see my DIY choke video) To tell the difference count the wires. A choke will only have 2 wires, a transformer will have 3 or more. Also before I started doing videos chokes on eBay could be had for $25 or less shipped but now that more people are looking for them (due to my videos) the eBay sellers have raised their prices quite a bit. Your best bet might be the DIY option out of a Microwave transformer. Please let me know if I can be of further assistance.
@@dazecars hey thanks for the reply, since i posted that comment ive found the diy choke video of yours. Very very helpfull, i have several m.o.t.s already lol. That is the route i will go for now untill i plunder more treadmills, thanks alot my friend. Im not a fan of many youtubers because most seem to only be after likes and to boast about what they have or can do lol. You actually put out practical reasonable and realistic information and i for one appriceate it
@@robertolson6686 Glad you like my channel. The comment you are making is exactly my goal. My channel is about the information and NOT about me (That is why I don't appear in any of my videos) Sadly in order for CZcams's search feature to recomend my videos I need views, likes, and subscribers and that can be tough to get so if you ever have the chance to recomend my videos to others please do so.
This video misses a couple important numbers; voltage and power rating. If you are controlling 120VAC, there for peek 170V, the potentiometer should be rated for 200V. The 2W is the power rating of 2 watts. Using a pot with a lower power rating will most likely result in the magic smoke being released. It would be interesting to see this SCR reverse engineered. It would most likely be cheaper to swap out the capacitor for a smaller one to reduce the dead zone.
I could be mistaken but I believe the pot is only see a signal voltage not full voltage.
🙌🤲👐👌now I know u have turn up the end before it turns
Thank you sir 🙏 your are wonderful teacher.
I have picked a treadmill motor from a recycling depo but I notice it is a 120V but my wall sockets are 240V. I think I need a transformer but I only find up 60V power supplies on. 🤔 will it work it but the 60V
Thanks
a Varic might work. What is the voltage of the motor inside?
@@dazecars 120V DC. After seeing your next video I saw it.needed. a transformer
Could you not just add a separate resistor in line to make up the difference?
Yes and No. If you do that you will have the max resistance (so the minimum speed) but the resistance will never go below the value of the resistor you added so you will be sacrificing top end speed. I did exactly that on my band saw because I wanted to limit the top speed.
can we use the scr for 1phase 220v 5.5Kw motor?
no, usig an SCR as a way to slow down an AC motor will result in a motor that doesn't work very well and will shorten the life of the motor.
my plan is to slow down my motor at least by 40%, its just noisy when it run. any other alternative way to slow down the speed. unless I change the lower speed motor but loose the torque. I need to use at least 25Nm to run the system. it extruder for animal feed machine. thanks in advance..cheers
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Where on earth did you find a 120k ohm potentiometer?
eBay
Put a 200k resistor across the 500k pot to get a 142k pot. A 220k resistor makes a 152k pot. Much cheaper than buying a new pot.
A comment similar to this has been made by quite a few others and while it is a solution it is IMHO not the correct way to do it. Adding a resistor in parallel makes the potentiometer no longer linear. I would much rather spend a few bucks for the correct pot than add a resistor and lose consistency. Your technique would make much more sense if potentiometers were a lot more expensive than they actually are.
SCR stands for what? Yes, I’m a NOOB.
Silicon Controlled Rectifier