Build A Simple VFD or Variable Frequency Drive!

[@RobynTapps]

Love your videos.. no obnoxious music.. just dialogue, perfect to relax to..

[@Maadhawk]

An engineer knows he has achieved perfection, not when there is anything left to add, but when there is nothing left to take away.

[@josefaschwanden1502]

Strongly disagree

[@seancollins9745]

@@josefaschwanden1502 then you are not a good engineer , or you work for mercedes

[@unlokia]

Paul, do you know what a lovely guy you are? Well you should be told - you're calm, humble, happy and exceptional - you know me, I always speak how I feel. Even if I'm not VERY enthused about a particular video (rare, btw) I watch them because I enjoy your slow, careful and thorough style. You are such a blessing to me, I am sure many others will agree likewise. God bless you and Happy Christmas on your chair in what can only be assumed is... "Space Station V"

[@MrCarlsonsLab]

Thank You For your very kind words! Merry Christmas to you too!

[@unlokia]

Well people need to know, don't they :) - you're welcome, and thank you!

[@peterfitzpatrick7032]

unlokia Nice comment.... +1 from myself... 🎅

[@martinda7446]

He is the most amazing in this field - most likely no1 on the planet, I thought I was good, but simply don't reach his standards and couldn't. I'm much too slap dash in comparison. He is a technical Black Belt, 7th Dan master. The more I watch the clearer it is, and yes he is a delightful person too.

[@fenarris]

you wrote exactly what i was thinkin but with better delivery! my first thought was "this guy has to be The teacher". absolutely amazing instructional video! Mr Carlson has gotten one new Subscr. keep on the excellent work man! =)

[@JustinAlexanderBell]

Overclocked desoldering gun, nicely done.

[@ET_Don]

I actually laughed out loud when I read your comment. :)

[@sagebrushrepair]

Same. I love this comment.

[@waltschannel7465]

Excellent video, not only for the subject matter but for the patient, enthusiastic, detailed explainations! I had no idea what a variable frequency drive was or what it would be used for, but now I want to build my own for a noisy fountain pump. Way cool!

[@nazgullinux6601]

Your videos are like ASMR for electrical engineers. Awesome content, awesome and knowledgeable engineer making that content, and no rubbish. You are a joy forever. Thanks for what you do.

[@martinda7446]

Mind boggling attention to detail. Extraordinary professionalism. Don't think there could be another like Mr Carlson.....Er, I'm just a little jealous.

[@armandine2]

Phillip Schofield is a television presenter who reminds me of Paul - similar un-flustered delivery

[@alfredytmalveo9]

Excellent video, This is the highest quality video I have ever seen on KZbin….. You are amazing …..

[@danielspattenjr6237]

Paul your level of professionalism in every thing is bar none , I always try an watch your videos , I've learned so much already thanks for doing this for all of us noobs because you explain everything for a layman to really understand I'm gonna try an build one of these drives because I'm a clock repair man and I have multiple machines that need this

[@MrCarlsonsLab]

I'm glad you found this useful Daniel! Thanks for your feedback as well.

[@orange70383]

You'd be hard pressed to find a smarter, wiser, better natured guy than this dude right here . A very Merry Christmas to you sir'

[@MrCarlsonsLab]

Thanks For your very kind comment! Merry Christmas right back!

[@NipkowDisk]

I agree 1000%- Mr. Carlson is an incredibly gifted, seemingly natural teacher. Such people are very rare.

[@tinfore]

This could be very handy for large aquarium pumps. Thanks for sharing! That VFD is soooo much more simple than those such as the Allen Bradley ones. We used to use the 1336 drives a lot at work but now they are being phased out and we now use PowerFlex400 or 700 among other larger units.

[@ianbutler1983]

Thanks Paul, I was hoping you would do a video on this. I remember your mentioning it a few times. You builds are always professional looking. Mine look like they were done at gunpoint.

[@MrCarlsonsLab]

LOL, Thanks Ian!

[@sincerelyyours7538]

I really love this design and the build quality is top notch. Your ability to explain things clearly for us budding tech types is the best I've seen online, please keep up the great work! I also liked the way you provided a way to quickly return this device to its original format. I always try to do nothing I can't undo later - saved my butt many times over the years!

[@MrCarlsonsLab]

Thanks for your kind comment, and feedback too!

[@normdoty]

most excellent idea , fit , form , and function.. super job keep up the great work.. i just love your productions..

[@avril1556677]

So many followers happy with your hand-drawn--only--schematic. Interesting.

[@mikemullenix6956]

Mr Carlson, Gods gift to the electronic world. only Paul could hot rod a hako desoldering tool! Electrical engineer of engineers.Mr Carlson always overengineres everything so it will last 2 lifetimes

[@foolscrowstudio]

Thanks for this! I’ve been brainstorming a VFD circuit to control the run motor on a Hammond organ, it maintains its tuning via mains Hz. With this I could bend pitches which would be amazing.

[@MrCarlsonsLab]

If you build something, make a video. It would be neat to hear that.

[@Dzonemp]

Now that is a solid design . Built to last .

[@SpellsOfTruth]

When I was working as a computer programmer 3 stories underground at a base somewhere down a dirt road in virginia. I once saw maintenance/janitor guy fixing something they rolled out of the electrical room while I was walking to lunch. I only saw it for about 2 seconds, but it had a coil wrapping that was fascinating. The wrapping of the coil was not around a cylinder of iron or plastic. It didnt look like any normal looking wrapped coils. It was widely wrapped around different geometric shapes. There were about 12 stacks and each stack was offset so that when the entire coil was wrapped with the copper wire, the wire would protrude a little bit on each stack. Imagine a pole, and you slide down 12 6x6x2 square blocks, and then offset the blocks so it spirals upward, then lock the blocks in position and wrap the copper around the blocks, so the coil wire is not evenly lined up because it gets wrapped around the different position blocks. This is just me trying to paint a better picture of what I saw, it didn't necessarily spiral upward, could have been a more discordant different pattern of blocks, could have been different shapes than blocks. Basically they were using 'sacred geometry' as the basis for their copper coil. I thought that it must do some crazy stuff with the freqency, and wavelength, perhaps there using it to mess with phases idk. If anyone would know what that was, its you imo haha. Have you ever seen coils wrapped like that?

[@skycarl]

Well Paul, once again you have taken what would be a complex unit and broken it down so it is understandable. Thank you as always and great design and build my friend.

[@MrCarlsonsLab]

Thanks Skycarl!

[@miroslavbencic9582]

A good improver to beat the pump's performance and thus to ensure quicker suction of tin from the circuit, I like it! Mr Carlson's I wish you a happy and merry Christmas! With Regards Miroslav from Slovakia Bratislava. :-)

[@MrCarlsonsLab]

Thanks Miroslav. Merry Christmas to you as well!

[@miroslavbencic9582]

Thank you Mr. Carlson's!

[@jerrymont2595]

Fabulous, Mr. Carlson. I'm getting an understanding about the differences between a SCR drive and the VFD drive. Thanks !

[@georgelewisray]

AUDIO Glitch & Thanks : : : The audio faded out several times as you moved around. I was able to get the important stuff , no problem. /// As usual your topic, knowledge, style of presentation and demeanor are World Class !!! Thanks for what you do.

[@mathewbailey6718]

What about a VFD for single phase motors? Some of the Seeburg jukeboxes use an auto speed unit that enable them to play 7 inch 45 & 7 inch 33 rpm records. The Seeburg auto speed unit is basically a single phase VFD that raises or lowers the AC frequency to the turntable motor to play either 33 or 45 rpm. Newer Seeburg jukeboxes have an auto speed unit as an option.

[@atbglenn]

Merry Christmas Paul. You're a brilliant guy in this field and we all appreciate your videos. I have a Hakko 808. Works amazingly well for my needs. I can only imagine how much better yours is stock, let alone with the mod you made.

[@MrCarlsonsLab]

Thanks Glenn, and Merry Christmas to you too!

[@shawnbottom4769]

Can this get a part 2? I wanted to see the output waveform.

[@frankkoslowski6917]

Interesting circuit. Good for those who can get their hands on a HAKO destoldering unit without having to mortage their house.

[@johnstark5324]

OK, I work on a lot of old Teac "A" series decks. These use an induction motor and for some unknown reason they start to slow down. Is there a way to make a unit like this for speeding up these motors? The one of concern is the capstan of course. For those who think the cure is as simple as cleaning the insides and lubing this has been tried by many a tech, this is not the problem.

[@AThreeDogNight]

Merry Christmas Paul & thank you for all of your time & expertise on all of your videos because you are helping so many people to understand, do repairs & even make their own items or boards because of you so once again many thanks from all of us & a very Merry Christmas to you & yours with a Happy New Year as well my friend, God Bless!

[@MrCarlsonsLab]

Thank You for your kind words and Blessings Thomas! Merry Christmas to you and yours as well!

[@rahulbindhu]

Perfectly explained so that even noobs like me understand it.

[@jimb032]

Always appreciate your great videos. You are such a wealth of knowledge, and so easy to listen to. You do such a professional job on your videos, and they always seem so well prepared. Thanks so much for taking the time to do them. Hope you have a Merry Christmas!

[@MrCarlsonsLab]

Thanks for your kind comment James! Merry Christmas to you as well!

[@overkillaudioinc]

I have built a number of VFD drives for turntables using an oscillator to drive small audio amplifier like a LM3886 that drives a 120/12v torriod backwards. Most turntables only need about 90vac, but you can easily get 120vac also. you can also build as large a version of this you want using commercial PA amplifiers. Old crown DC300's, Peavey CS800's etc. work well

[@doug8718]

Great video! One minor detail...the Hakko sales reps I have spoken to pronounce the name with a short "a" as in the work "hack".

[@isoguy.]

Another great video from the master himself. Have a great Christmas & thankyou

[@MrCarlsonsLab]

Thanks, and Merry Christmas to you as well!

[@fvckyoutubescensorshipandt2718]

Dang, didn't think you could get a sine wave without some sort of resonant LC circuit. Learn something new every day.

[@jjr56991]

Another fantastic video. Thanks for taking the time to share your knowledge with us, it's very much appreciated.

[@jamest.5001]

I have been looking for a single phase VFD. I would hope for a cleaner sine wave! great video.

[@ET_Don]

Tim "The Tool Man" Taylor would be proud! :) Thanks for another great video. Paul, I sent you a message with a question regarding DMM's. Wishing you and your family a Belated Happy Thanksgiving, and an early Merry Christmas / Happy New Year.

[@MrCarlsonsLab]

Thanks Donnie! Merry Christmas and New Year to you too!

[@foureyedchick]

Hi Paul. This is an excellent video and it is very informative. The concept of using your VFD to control the induction motor is brilliant. HAVE A WONDERFUL CHRISTMAS & HOLIDAY SEASON ! 😀😀

[@MrCarlsonsLab]

Thanks Nerdygirl! have a wonderful Christmas as well!

[@cdrive5757]

Scoped Output would have been nice to see. Especially since you have so many of them! Wakodahatchee Chris

[@maurirodriguezdj]

Too advanced for a beginner like me.. but i love your videos i always learn something new.. you are god! Thanks from Argentina

[@MrCarlsonsLab]

You are too kind Mauri! Thank you!

[@johnsweda2999]

Why have the open slits on the top and have the fan as well and you put extra holes underneath? You can quiet it down by inserting some self adhesive bitumen pads inside the casing. Get foil coated ones and non foil what they use in the car industry, this make it a lot quieter, and try installing the fan on some rubber grommets so it's floating. And maybe turning it upside down and having feet on the other side and having a bitumen pad underneath for it to sit on. I'm building a high end turntable and I'm looking what is my biggest problem! is for me is the motor and power supply I really want to go with AC, Would this be suitable with a conversion ? Running at 100 Hz and or 120 Hz. And any good suggestions on Motors. If I can get wow and Flutter below 0.024 or lower on a belt driven on a sophisticated double platter system.

[@Alrukitaf]

👍🏽👍🏽👍🏽 great info very well presented. The circuit diagram was pure gold!

[@raulopatriot9034]

...a lot of knowledge right there! AWESOME. THANK YOU

[@paul7195]

It might be a good idea to connect a fuse on both sides of the AC line going into the unit, as sometimes the hot and neutral are reversed.

[@lionelguy]

Hi Paul, as was mentioned earlier, mount the fan on isolator feet. That will quiet the noise.

[@murdoch817]

Another in the LONG string of great topics! I work with VFDs a lot (maintenance on CNCs + other equipment as a machinist). Such an elegant design, as opposed to the over engineered units I an accustomed to IMHO. Thanks so much for explaining and sharing the schematic, it is going on my project list. What type of camera do you use for your video work? Pics are always great quality. Many thanks again, Doug

[@MrCarlsonsLab]

Thanks for your kind comment Doug! The camera is a Canon C100 Mark II.

[@vylbird8014]

Simple, but at a cost: You're only going to get a 'sineish' wave at best from it, with the efficiency loss and increased motor heat dissipation that implies. But for driving a dinky little motor, that's not a problem.

[@stevec5000]

Old Maytag Neptune front loading washers circa 1998 have a nice variable speed 3 phase AC motor with a speed control built in that you can pickup used for a few bucks. The speed control only has 3 connections, a serial data input from the control board that tells it what speed and direction to run, a tach output so the control board can monitor the speed and AC power. I wonder how hard it would be to setup an Arduino to control the speed? There's an article on Hackaday with more information about how the motor works but they haven't advanced to the point of using a micro controller to control the variable speed system. hackaday.io/project/28630-variable-speed-washer-motor-and-controller-reuse

[@stephenborst3535]

Thank you for the video and happy holidays Mr. Carlson.

[@MrCarlsonsLab]

Thanks Stephen, Merry Christmas!

[@sincerelyyours7538]

I kind of wish I'd seen this a few months ago. After much searching, I ended up with a Hakko FR-300 self-contained desoldering iron/pump instead of the 802 desoldering iron/470 pump system. Like you, I'd have preferred modifying a used device and making it better than new, but I must admit the FR-300 is an excellent tool as is. If it ever breaks maybe I'll take what I've learned here and make it better... By the way, since Hakko is a Japanese name spelled with two "k"s, I believe it is more properly pronounced "Hah-ko" rather than "Hay-ko", though only people who live in Japan would know the difference. Love your videos Paul. Happy Holidays!

[@MrCarlsonsLab]

You know, I worked beside an engineer years ago, he mentioned the same thing... Your probably correct!

[@skeggjoldgunnr3167]

Indeed, "Hah-ko" is the correct way to pronounce this...but that makes it difficult to rhyme "Fake-o" . We like to have our fun. I understand.

[@fersunk]

I don't live in Japan but I know how to spell it correctly. The funny thing is that *almost whatever native English speaker pronounce the words of another language in that form. I speak Spanish and I know how to spell it correctly at first glance (they way it's pronounced make it easier I guess). It's easier to learn another romance languages and japanese (at least how to spell it)

[@GlennHamblin]

Very nice minimalist design. Thanks. Now onto 3 phase drive. 😁

[@raymundhofmann7661]

Wow, this APT5022 is tough, switching 12uF to 150V in microsecond times. Luckily it only does it below 100Hz. What about putting the 3x4uF on the transformer secondary side? The stray inductance filters and then discharging into the fet in avalanche might be less tough and also possibly better for EMI.

[@theskett]

Yeah, that "FET switches 12uF directly across the 150V" aspect made me flinch a bit, too; I'da added a low-value series snubber resistor between the FET and LC components. And I suppose if the caps were across the secondary, they should be higher value (per transformer turns ratio) but could be rather lower voltage. But as Mr C. says, it's been working for years; so it's definitely Good Enough as-is :-)

[@latasha66]

"Rectified Mains" will be my new band name

[@koushiks_energy]

Shall I join

[@leberkassemmel]

This is interesting. Not the approach i would have used, but it is always interesting to learn something new.

[@Brokendiode]

That's a pretty cheap and simple way of doing that, and I am a little surprised that it works as well as it does, although single ended flyback power supply's are quite common and work quite well, they are simply rectifying and filtering the output, and using negative feedback to control the duty cycle of the mosfet to provide regulation, those power supply's use a powdered iron core that is non saturable meaning that it has a good Q factor as an inductor, which is generally not the case with low frequency laminated iron core power supply transformers such as the one you are using, they tend to be very saturable unless you take the core apart and re stack it with all the "E's" in one stack and the "I's" in another and then place a thin piece of cardboard such as that from the back of a notepad between the "E's" an "I's" to break the magnetic circuit so it won't retain high levels of residual magnetism, thereby allowing it to have a much higher "Q", and as someone else commented, about the current pulses that occur when that mosfet turns on and those capacitors in parallel with the transformer primary are at zero volts or even worse opposite polarity, you might consider adding a resistor of say 10 ohms or so just to limit the current peek a little, it'll reduce the stress on the capacitors and the mosfet.

[@MrHDtom]

I like this gray hammertone design !

[@jimkodysz5404]

I always learn something from your videos, Paul! Thank you! Avery merry Christmas to you and your family! 🎅🏻 🎄

[@MrCarlsonsLab]

Thanks Jim, Merry Christmas to you and your family as well!

[@KieranHarkin]

This ties perfectly into the videos that AvE has been doing nice one!

[@MrCarlsonsLab]

Weird coincidence.

[@unlokia]

Except with no profanity (uncalled for) and no sycophantic Ave fanboys parroting his "catch phrases" to much cringing.

[@kentvandervelden]

What variant of English does he actually speak? Is far-north Canadian? I have a horrible time understanding him.

[@EscapeMCP]

Amen on the parrots

[@robertcalkjr.8325]

unlokia Yeah, and if you question anything you'll receive an onslaught of insults. But I can't complain - dumping that channel aided in my finding Mr. Carlson's Lab, so I'm happy! Also to all the closed minded sycophants there, I'll be wearing my Shaxon anti-static wristband again this winter(without a tether of course) to keep myself from being shocked when I touch stuff or getting in and out of my car. lol!

[@TheRadioShop]

That was a well worth modification Paul. All that baby needs now is some chrome to go along with that hot rod engine! Thanks for sharing.

[@MrCarlsonsLab]

Any time Buddy! Wishing you a Merry Christmas from our end!

[@the8bitbarn836]

Well I must say that was really cool, Over the years I have souped up many things but never a piece of bench equipment. that got me thinking, I have a small drill press (AKA) a harbor freight nightmare it's too slow to drill PCBs and I'm considering building a unit like yours but the question comes to mind, why not just a frequency doubler inside the hako unit? I do like the stock plug option! So as I understand this a bit more the external power will not supply any voltage out unless the opto is triggered. So that would mean that the original voltage supplied to the motor inside hako unit is used to signal the external power supply, Nice they work together or not at all. Another cool design! Love your videos!

[@mikesradiorepair]

NOS injection system for desoldering guns. :-) Great upgrade. Thanks for sharing. Mike

[@mickeyfilmer5551]

That is a heck of a difference.

[@rrangana11]

Very nice work Mr. Carlson. Thanks for sharing and Merry Christmas...

[@MrCarlsonsLab]

Merry Christmas to you as well!

[@markhod1960]

Great vid Paul as always. And have a great new year.

[@MrCarlsonsLab]

Thanks Mark, Happy New Year to you too!

[@PileOfEmptyTapes]

Re: fan noise, I advise you take a page out of silent PC builders' book. Some of these rubber nipples that people use to elastically mount fans and a bit of bitumen mat here and there should go a long way. You've been hard mounting a fan to a stiff, resonant metal structure with just about zero internal damping, so what do you expect. It's pretty much an ideal acoustic amplifier (or rather impedance transformer with built-in echo).

[@poptartmcjelly7054]

So it's basically a flyback power supply without a rectifier at the secondary, right? Does the primary side not require any snubber or is there no significant flyback voltage since it's operating this way?

[@banjoperator]

i have been through almost all your vids and as a complete beginner coming back to my interest in electronics i have found your channel to be one of my go tos for information which by the way has been awesome.. in all of what i have seen so far one thing has me curious.. with all of the test equipment you run.. what is the mains amperage service you run it all off.. again an awesome and informative channel for noobies..

[@MrCarlsonsLab]

Hi. Only a few pieces are ever on at a time, so nothing major. Probably less than a toaster or hairdryer.

[@banjoperator]

awesome..Merry Christmas to you and yours

[@ZXoney]

Using Rubber Grommets from fan to chassis could help with that noise! ;)

[@dzee9481]

Paul could you explain how a single phase VFD that produces a 3 phase output works. Like those found in powering a CNC spindle from single phase. You dont see many schematics out on the web that shows details of such a unit. There are schematics for 3 phase to 3 phase VFD. But as for the Single phase 120 or 240 volt units obscure the parts that produce the 3 phasing. I understand how a 3 phase inverter works using a pony motor. where the pony motor has to be same size or bigger than the motor you are driving in terms of horse power.

[@alchemy1]

I am very confused on how to provide power to a Treadmill type of motor. It is definitely brushelss Magnetic rotor motor. I have this nice motor that needs 100VDC and 21A rating. Can I use one of them chinese light dimmer AC adjustable thing with a full bridge rectifier or how can I go about it? Thanks in advance for any feedback.

[@kentvandervelden]

Very nice explanation. I actually understand this circuit. That certainly cannot be said for my Hitachi VFD.

[@kkendall99]

I've worked in a few labs, biomedical engineering and general technician level, your lab looks like an over ambitious Hollywood producers idea of what a lab actually looks like. I do however appreciate the fact that you are a fellow ham so keep up the good work. KD7YCX

[@Factory400]

I will go with ZEENER :-) Excellent as usual. Really appreciate this channel.

[@victoryfirst2878]

I have to agree with you on the minimalist strategy you used on your design vfd. What I am wondering about is it possible to raise the voltage from 220 to 440 volts using a vfd with input being 230 volts ??? Also, why are Hacco products so expensive ??? I have a weller that really works great without breaking the bank on purchase. Thank Mr. Carlson's Lab. Peace

[@foxyrollouts]

love your vids, have more meat than eev, im a first yr engineer, loved your explanation of the circuit

[@Ronnie9710]

Great add on to your pump Paul.But that way over my head.

[@mikemoulton5309]

Do the three capacitors in parallel with the transformer form a tank circuit? Where does all that current go when the MOSFET switches off?

[@transcendentdiety936]

So I'm totally unfamiliar with using a VFD to drive a single phase motor. In my line of work anything with inverters or drives is driving a 3 phase motor. I was wondering if increasing the frequency to the run capacitor would affect the longevity of the capacitor at all? Also was wondering what effect, if any, the drive would have on the inrush current of the motor.

[@Geopholus]

Very interesting project. I builtSomething similar almost 50 years ago. Later i've used a power amp, with a sine oscillator to drive it. Output transformer helps to boost up the voltage. By the way my Patreon account collects 10$ from me each Month, but never lets me see your video's even though they send a preview of them every month. So i get to see your video's after they are old.

[@MrBranboom]

Might try some squiggle of hot glue on the inside of the case walls to deaden the sound if it bothers you. Though, by the look of your lab, it's all part of the ambiance. Great vid! I'd like to base a one-of controller build off your schematic, if you don't mind.

[@zaidhussain5206]

Thank you so much for the great lecture it was very informative to me.

[@stevedoubleu99B]

Merry Christmas, Mr Carlson.

[@MrCarlsonsLab]

Merry Christmas Steve!

[@jdlives8992]

Would something like this work for making 120 60hv to 120 80 to 200hz 120v around 3 amps ?

[@petenikolic5244]

Is that designed for 120 vac or 240 vac . I am thinking of using thius circuit to sepped up my somewhat slw CDE Ham II rotator it has a 30 volt ac motor but is as low as treacle

[@kkendall99]

Very cool, one thing I can't figure out is why you supplied the control circuit with 20 watts of potential power?

[@Mulazim.]

Does increasing frequency could increases power consumption?

[@MrJakelstr]

How does the transformer end up with a positive and negative half wave, with only a single FET? I'm more used to the H-bridge design that can route power either direction to create that

[@Ricardo-uw3ov]

"it is easy" Yeap, for you that are a god damn master of electronics art!! Thanks for sharing!

[@SoundsLikeOdie]

Normal person. Hmm I need more suction. Let me upgrade the pump motor. Mr Carlson. Hmm I need more suction. l'll create a VFD drive. Nice work btw.

[@emmanueleferrarotto2986]

Regarding the noisy fan: Have you tried to isolate the fan's vibration from the case by using some sort of rubber beetween fan and case?

[@MrCarlsonsLab]

I tried it all, unfortunately sound deadening material won't fit inside, and rubber mounting the fan made an extremely small difference.

[@laharl2k]

One thing, you used 4 5W resistors to power the ic, I think a much better solution would be a circuit i saw on an emergency lamp board. Its just a capasitor as a reactance followed by a small resistor, a zener and a transistor and an electrolitic cap, all low voltaje. The circuit had a fault that the electrolitic cap was too small and so if you plugged it in at the peak of the sine wave it would overshoot and burn the transistor. The solution was to make the cap bigger so it wouldnt be able to overshoot. The input capasitor takes the bulk of the voltage drop and then its a simple zener-transistor regulator with a resistor to dump the power the IC isnt using. (the resistor should handle a bit more power than the peak the ic can consume just to be safe). Maybe its a bit more complicated but at least its not a 20W heater inside a case. This board had a 2W resistor which suplied the charger circuit for some 4V SLA batteries that powered the leds strips.

[@crzy11000]

I was wondering if you mounted the fan with rubber spacers to soften the vibration would that help with the noise? I imagine you tried that though. Your explination of the schematic was verry informative and clear to a novice like me. Thanxx

[@allthegearnoidea6752]

I note your feeding the transformer with pulsed DC. How come the transformer core doesn’t become permanently magnetised in one direction and inefficient. Thanks regards chris

[@MrCarlsonsLab]

All SMPS's would have big problems if that happened :^)

[@victoryfirst2878]

Would you be able to make a 20 H.P. single phase 240 volts ??? Or at least show or tell me how would be the ticket Mr. Carlson's Lab ??? Thanks

[@DeathrashWhiplash]

Some fine electrical engineering sir

[@rimmersbryggeri]

Could you used a vfd like this to get a turntable to run at the right speed? Or is the current too choppy?

[@drewsmith6066]

This guys a wizard.

[@strangersound]

No doubt about it. :)

[@tom7601]

I used to watch Mr. Wizard on TV, back in the 1950s. There are some of his videos on KZbin.

[@TheCalvinSkinner]

With a VFD, assuming the output waveform is a sine wave, how is the frequency changed while maintaining a sine shape. I would think smoothing capacitors would give a limited frequency range; that the output would become a square wave or something else at high or low frequencies. What is the frequency range of this VFD?

[@TheRenaissanceBuilder]

Hi, if i may ask, Is it ok if i use this circuit design in a video? Also, what would happen to the transformer if you left out the thee capacitors?

[@Fourcycle]

Well done! You got me thinking. I wonder how difficult it would be to modify a UPS to be variable frequency? I have a few of those kicking around...

[@MrCarlsonsLab]

Could be done!

[@Fourcycle]

I played with a little 12vdc in, 120vac out, 150W modified sine wave inverter today. The plastic can-style case, designed to go into the cup holder in your car, was turning gooey for some reason so I pulled out the electronics. It uses two TL494's. One running at ~40KHz to step up the 12vdc to 150vdc, via a ferrite transformer, then rectified and filtered. The other TL494 running at 60Hz (Or was it 120Hz? I forget.) drove FET's configured in a H-bridge to push and pull the 150v through the load. I ran a shaded pole motor with it and was able to adjust the speed by changing the value of the resistor in the second TL494's oscillator circuit. Pretty ratty looking "modified sine wave" but it worked! The whole inverter, including the heatsink, was on a board measuring 3" x 2" x 1.25" and seemed very efficient, the motor getting much warmer than the tiny heatsink. One could even eliminate the first TL494 by rectifying the line and using the second TL494 to drive the load via it's H-bridge. If the line filtered voltage is too high, one can use a transformer in the traditional sense, or reduce the line voltage by putting the secondary in series with the line anti-phase. Just be sure to use a isolation X-former on the line side while figuring things out to keep from being knocked off your noodle :o) A schematic of the inverter can be found if you do a search for "Common vehicle carried inverter". One of the hits will have a BOM to go with the schematic.