Wiring a DC motor and Universal motor for speed control. I use a vacuum motor, electric lawn mower, and Treadmill motors to demonstration some cheap options for speed control and wiring to the wall.
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Any additional notes will be added here.
1. The biggest difference between using the HF speed controller and the DC speed controller (other than reliability) is the speed controller dynamically adjust the speed as the load increases. If you just use the HF speed controller the motor will slow down under load. The KB speed controller is “smart” and will adjust the the power output to maintain the speed.
2. The Auto transformer is also often called a “VARIAC” and I bought mine on ebay for $90 new. Model number TDGC2-2MK. It can handle up to 20 amps which should be plenty for most people.
Final Note:
PLEASE UNDERSTAND…I receive hundreds of messages on all platforms (email, Facebook, Instagram, comments, etc) asking for advice, and help with projects. At this volume, I simply can’t do one on one advice. I have tried to help enough times to know I should never assume I have all the relevant information in the message, and even basic questions can produce a lot of followup questions. I do read all the questions, and if I get the same ones over and over I make videos about it to help lots of people. Thanks for your understanding on this.
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Very informative. Love how you explained all the different options including the hf one you didn't like. You are a YouTube I would happily pay to watch. Your style, explanations and material is fascinating. Thank you
Hi Jeremy (or anyone for that matter). Does using a variable transformer drop the torque of the motor when it’s running at low rpm? Thanks.
I like your videoa, thanks for making them
Gotta say, as important as it is to learn how to design circuits from scratch for custom projects, I am a HUGE fan of repurposing old equipment/electronics. You're a wonderful teacher, thank you for all you do.
Love your videos…you make it easy to understand…..so informative….THANK YOU
cheapest way to reduce AC voltage is by using light bulbs as resistors, Higher wattage light bulbs will produce a higher voltage and the current will always be limited by the light bulb.
A 10,000 micro Farad capacitor would be HUGE. That's 10 mili Farad or 0.01 Farad. The only purpose of a capacitor in this setup (DC motor instead of AC) is to bleed off the energy stored in the motor as inductance (anything with a coil of wire has inductance) so that it doesn't damage the rectifier when the power to the motor is turned off.
Caps are used in AC motors to bring the voltage and current in phase since the inductance of the motor causes them to go out of phase which results in lower speed and torque and higher operating temp. In this case, the caps have to be matched to the motors inductance and the motors name plate will state what that value should be. They're always a common size and are cheap and easy to get. That's not a problem with DC motors, well…because they're DC…they don't have a phase.
Inductors store magnetic energy when voltage is applied and when voltage is removed that energy is released back into the system. It's similar to how a flywheel stores and releases rotational energy. The voltage and current is usually MUCH higher than what was fed into it. So it's usually a good practice to provide a path for releasing that energy so that it doesn't feed back into the electrical circuit and damage sensitive electronic parts. In smaller circuits a diode is used and a capacitor (who's Farad rating isn't critical) is optional but still good practice.
Since you already have 4 diodes in the rectifier that are wired the same way as the one mentioned above, I don't think you need anything. You could put a 15 micro Farad, 370 V run cap on it if you're concerned. I've never seen anyone do that in their designs though and no one has reported any problems. Personally, I wouldn't put one on but I'd talk to an actual electrical engineer to tell you if you need one and what size it should be if you do.
People also use a cheap motor controller sold on ebay and the same rectifier you're using plus a potentiometer (for about $10 – $15 total) and they haven't had any problems. I don't think they have a lag on startup either but I could be mistaken. I don't know if the motor is supposed to have pulse width modulation or not either. It might run more efficiently that way but I don't know. It'd be nice to see what your board is outputting to the motor on an oscilloscope to see if it's PWM.
Anyway, great videos! Please keep it up!
you are the best teacher in the world!!!!! easy to understand right to the point, no lousy music!!!! thank you very much!!!!
Hi jeremy!i salvage a hitachi washing machine motor rated 110-120v ac,its an imported washing machine its in japanese. this motor has 3 pins and a separate 2 wire,i was wondering what are the 2 wires for beacause the 3 pins is from the coils inside i think its a brushless motor. Can`t find the schematic diagram and since the motor do not have any label.
Thanks very helpful
Jeremy, You had me freaked out a little holding the light dimmer as too many places on back to get 60 buzzes per second. I haven’t look recently but controlling the frequency on A/C system has been the rage. By controlling the frequency while using the correct motor is the ability to control slower speeds, reduces loads, lower current is the holy grail for them to get SEER ratings into the low to mid 20’s when just a few years ago, a SEER rating of 18 or 19 was consider extremely high. I have seen SEER ratings up to 26 but getting training, info almost requires a license or a buddy in the field. But having the ability to drop compressor speeds to the minimum need to run an A/C system and the blower fan speeds gives an company the ability to show a buyer how a higher up-front cost will pay for its self two to three time faster in the form of lower utility bills for an appliance that may actually last way longer.
A decade ago, the A/C system was either on full blast or completely off. This led to ECM motors that where expensive as it was on part. Then the second design was the motor end-cap contained the ECM portion with all the electronics in it to be serviced separate. This reduces inventory, labor & total cost. It’s just an idea if you have or have not looked into it.
I understand that what you or I would want is something that is more universal. Like buying tools. If you find a tool that works but only does one thing, great. But if I could spend $5 more for a quality tool that does 4 or 5 things is a smart multitasker. I really enjoy how you explain and show the work in your videos. You have had great videos and worth like, subscribe and binge watch the entire channel. It will get your electrons going!!!
I have a little 12 volt motor and was thinking of just getting a dimmer switch to put on the circuit to control the speed. Will that work?
The triac probably doesn't have enough power to start up the motor until you have it at higher voltage. The full bridge rectifier also causes a voltage drop which further lowers the power.
Great info, Jeremy, thanks
I want to build a small lift for "hide a hose" system, for central vacuum hose. I purchased what's called jazzy wheelchair motor on eBay with 2 wires coming out of it. I also have an old laptop power supply labeled: " 130W 20V/5V, 6.5A/1A, Input 100-240V", and that's where my knowledge stop.
I learned from your video today about "Rectifier", because the motor is 12V/24V. I guess I will be heading to eBay again
how to wire a variable speed control motor for peddle bicycle
Any reason not to use something like this $39 speed controller 100A 3000W Programable Reversible DC Motor Speed Controller PWM Regulator US
wonder why you did not use the speed controller from the treadmill?
???
Great video. I appreciate you posting this, and showing various ways to get these motors to work. Thanks!!
Thanks for such an understandable break down on so many different options for accomplishing this project. I’m teaching my 6 year old grandson how to make an electric motor and now we have moved on to more complex things and he has a complete understanding of what he is doing, so your videos help me understand things that I’ve worked with for years in a way that I can pass on to him. You are a great inspiration and an excellent teacher.
Always excellent your videos! Harbor Freight is garbage.
Hi Jeremy, great video which has helped me complete a couple projects I’ve been working on. Just one question, I’ve installed my first speed controller, transformer and bridge rectifier plus lots of wires in a 6”x8”x 3” plastic box, how much heat build up in a closed box like that? The setup is used on my lathe.
I have a question for you are you running them lathe motor underpowered? Because I'm familiar with that motor it's the same type they put in the lathes
It's an exceptionally fast running motor and it seems like it's way underpowered in this video I saw you max out the potentiometer and it sounded like it was running at about less than half of what it should be. This is important for me to know because I will avoid that controller that you used in this video if if it's not capable of running the motor at full speed. Unfortunately I lost the controller boards that are meant to run that motor so I'm looking for an alternative. I suppose I could using microwave Transformer in fully Rectify that and run it off of a variac but I'd really like a more elegant solution
Awesome video!!! Been watching your series more and more often mainly because its very informative and most of all not in hindi lol .. anyways so i wanted to make a suggestion about running thw motor by battery power and i happen to have made a airless paint sprayer motor run with 2 caps. First i tried the 470uF in parallel and run somewhat ok but then i tried usingthe 330uF the same way and i am not certain but it seems to run a bit better. My opinion would be the way im delivering the current the dual 330 uF is more lite weight to drive than the 470 uF in parallel but if it helps you to go from there well ill be a very proud and accomplished person ?. Thanks for all your videos i watched so far really helps me out in my projects at night after getting home from work
I've been wanting a belt sander and bench grinder for a while now. You've motivated me to salvage some motors and build them myself. Thank you.