Ferroresonant AC mains voltage regulator (BLACK MAGIC BOX) 

Never give this treasure away! In these days nobody would build such a robust device with 10kg iron

When I was a kid, I tore down quite a few of these devices. My grandpa and other relatives used them in 60s-70s when there weren't any electrical grid, just some local town generators with awfully bad frequency and voltage fluctuations (could see light bulb blinking with bare eyes). He said, that TV would just fry without one of these, always wondered, how do they work...

Never properly knew how those things worked even after reading the Wikipedia article about them, great video explains it well! Loved the LED rolling shutter trick as well.

Bloody hell, now all the audiophiles are going to get out there and buy all remaining stock of these things so that they have regulated voltage for their turntables!!!

ohhh, I have to remember the rolling shutter trick. That was clever

It looks like black magic but it really is german engineering. They're easy to mistake. ;)

I would love a demonstration of why gap Vs no-gap cores is important/makes a difference - for instance why usb power supply topologies require the gap, and maybe some nice graphing like you have done here, just remove some mystery! Thanks for a quality video.

I own several modern iterations of this device, following a local power line accident that shorted out some electronics in my house. These devices are so much better than anything with a MOV design. They are expensive, but are military specification and I don't need to worry about them burning out without warning.

This kind of blew my mind throughout the whole video. At first, because I had no idea how this was even possible. Second, because you did such a good job explaining HOW it works so, by the end, I understood! Is this what people call elegant engineering? I definitely think so.

In 1962 I worked in a mobile telecommunications repair truck. It was fitted with a ferroresonate AC regulator as the power source was usually a 240 V AC mobile generator. The unit was made in England and worked well without any active components.

I worked at a UPS factory that made ferroresonant voltage regulated equipment. Interestingly, input power could miss several cycles, and the device output would remain. This was possible because of how much energy is stored in the electric and magnetic fields of the regulator.

One of the most interesting topics in years on the entire youtube thing. Thank you!

To the donor: Thank you! 🙏 I really enjoy DGW video’s and your donation made this one possible. It’s amazing that the regulator is still in such an excellent condition and that you included the documents. Vielen Dank von ganzem Herzen!

This thing is amazing! Thanks to the donor and to you for sharing it with us and explaining how it uses seemingly simple I-C resonance(s) to accomplish a complex task that today would *require* active components to be commercially viable. Anything built with large inductors is obviously from the distant past as no one can afford such things today. Circuits today are built around active components and R-C filters and even then the capacitors are so cheap that they sometimes blow their guts upon first power-up :(. Large inductors were heavy and required a lot of metal resources, but they were more robust than the humans building and using them. It's likely that every human associated with this product in 1965 is now dead. The product outlived its application, however, and it will outlive all of us unless someone steals it for copper scrap. While products without useful purpose should be recycled into things that we now need, it would be a shame for something so amazing to wind up as copper-clad aluminum in some dodgy Chinese electronic product that will be thrown into a landfill 6 weeks after purchase :(. Can't wait to see it on the scope.

Beautiful engineering. Inductors have magical properties. I hope you can touch on the math in the next episode.

Many thanks for the explanation. When I started work (in about 1975), we had some problems with unstable mains supplies. My (old school) boss said "we should use a ferroresonant regulator". I had no idea what he was talking about, but I nodded. They were too expensive, and "normal" power supplies were improving, so we never got round to using an FR regulator. I didn't get round to studying what it was or how it worked at the time, but I've often wondered. Thanks again.

This is great. I've been wondering if such a thing was possible for a few years. Not enough to look it up, mind you. I figured it wasn't really a thing, mostly because, "apparently," no one made them. I thought maybe the range wasn't useful enough. But no, this one looks decently useful. Instead it's probably a matter of the cost of all that metal, and AC voltage not being important in 99% of applications, especially in 1965. Then later when precise voltages were required, we already had a bunch of solid state stuff to build better/cheaper/more-accurate designs. What a neat find, and so glad this was sent to you and you tore it down for us!

DIODE: You are AWESOME! Glad you didn’t tear down such a jewel! Thank you, thank you, thank you!

Good to see there are at least 74 ‘early viewers’! We really like to support your videooo’s … 😉

This is one of your only videos where I haven’t felt like I was able to keep up. I think I need more background with resonance and inductance

My great grandparents had one of these voltage stabilisators for TV. Line was single phase AC, about 2km from local transformer. Trouble was, neighbor had welder and my father told me that, when he was a child, whenever he welded lights would flash. They used it for radio and TV, which back then were using vacuum tubes and needed stable voltage. Using stabilisators, it could iron out the voltage. Otherwise, TV would flash and turn off. In the '90 line was upgraded, 3 phase AC and transformer was 80m from home. But old great grandparents were still using stabilisators. Their black and white TV kept working until digitalisation to DVB-T2 in 2015.

Magnetic/Induction based devices from past are all looks like some black magic. There's even some sort equivalent of transistor for AC, based on saturable inductor (or as it called "saturable reactor"): just add another winding apply DC to it so inductor go into saturation, inductance drops...and so does AC impedance.

This magical device is stunning! Thanks DiodeGoneWild an donor! Wonder how (in)efficient it is. Cliffhanger! Do we get to see the efficiency in the next video? Looking forward to the scope images.

"Any sufficiently simple technology is indistinguishable from black magic" - Carter C. Lark

Great video again, true understanding of basic electronics, almost a forgotten art!

I have a mains isolation transformer that also includes voltage regulation. It also has the "special" transformer with a bank of AC capacitors. The voltage regulation is unnecessary for what I needed, but it was cheap from a ham radio meet.

LED trick was brilliant !!

This is excellent explanation how this thing works, good job!

Need more LED rolling shutter tricks in the future, since transformer's functions are difficult to understand without destroying them. Great video!

Very clever technique to figure out phase dots from led and rolling shutter!!!

I remember that every TV was plugged into one of these in 80’s where I lived.

Great Video, clear, concise, accurate and just good all around. Please keep them coming. Cheers

A beautiful well researched description, thank you so much!

You clever clogs :-D My brain was trickling out of my ears lol.

Very interesting to watch. I did not know that such devices existed and how they work. Thanks.

Wow, I kinda get it, great explanation and smart use of your camera to demo the phase, black magic indeed !....cheers.

very good information. there's not much information over on ferrroresonant regulators. espacially on double core ones

Always enjoy your vids, many thanks.

I like how it is wired. It is a very neat job.

What I really wanna see is the next episode! The oscilloscope is there to increase the tension on the hanging end...

Very very interesting. Thanks for analyzing it, and kudos for the nice led/shutter phase detection trick. Also a big thank you to the donor. I can imagine these things in big, in use by power companies, for regulating line voltage.

Bloody hell that`s amazing... Nice vintage regulator. And in 18:50 that is genial idea, I will use this. Nice video as always

The US also had this. I believe the most prominent brand was SOLA. Zenith used this setup in their tvs in the 70s

Analogue stuff is totally awesome. So much cool stuff happening with a couple of "passive components"

That was fascinating. Can you do a follow-up video of what the waveforms look like when the input is not a clean sine wave? What happens when you feed it a stepped square-ish wave from a H-Bridge or something like that?

Wow man, you got some sick electronics knowledge! Also the led shutter trick was out of the box!

Solidní předvaděč spojitosti, hustý, něco takovýho bych nechtěl vypočítávat

very elegant design! great trick finding the windings with a LEDs strobing under frame rate...clever!

Das Teil gefällt mir. Super Technik!

18:50 And that was insanely cool!

Wow... I can only say WoW! I am speachless. That "old" technics is amazing, and also, How o how did you find áll that aspects from the working, how you could find out even the basicworking?!! Some of your video's are really jewels of knowledge gathering for us, but this one is stunning interesting good! Really Wow² !

I am also surprised how little electricity is inside, it is almost nothing and still more precise than many things you can buy today. thanks DGW and thanks to the nice gentlemen from germany for this interesting donation!!!! And a big KISS to your sweet CAT 💋 ☺️

Wow! Great explanation. Thank you!

Thanks for the explanation. Very good.

The Germans could probably build an entire computer with just inductors

👍 Danke fürs Hochladen! 👍 Thanks for uploading! 👍 Very good and beautiful, thank you! 👍 Sehr gut und schön, danke!

The important part of the regulation is the 50hz. So long as the grid frequency is correct, the output will be also.

Awesome explaination, thanks!

Brings back good memories and I'm impressed that the capacitors still work. Here in the USA, Sola is the champion maker of CVT and their winding configuration is a bit different. The resonating LC tank circuit is the same principle as IF (Intermediate Frequency) used in old radios (XL = Xc). Shunt regulators are very inefficient. Looking forward to the oscilloscope readings. Won't be surprised if there are distortions. Please more USB chargers videos and test Apple products. Thank you and I really enjoy your videos. Keep them coming and more often!!

There's also the Soviet version: a variac with a slightly dodgy servo motor connected to a type II controller made of resistors, capacitors and an op-amp. When the voltage changes the servo turns the dial.

This is really a clever invention back then and also a very smart analysis of its function by DGW :-) Today they would use a lot of semiconductions and Microprocessors to achieve this with much smaller lifetime i guess! This technique is 70 years old and works still perfectly!

Excelent explanation, waiting next video....

Bloody long but bloody interesting. Thanks.

Nice trick with the led's!!

Really interesting video! :)

Really interesting! - it must have been quite a lot of work to tweak something like that. Impressive engineering :)

Awesome piece of engineering.

Thanks a lot! I knew that this stuff exists and I always asked how an arrangement of "fixed" passives could act as a regulator.

This is absolutely amazing, wow... I can't help to wonder why this hasn't been more widespread, i have never seen a regulated power supply like this.

Well explained, thanks.

This give an idea for a voltage multiplier without no semiconductors, spark gaps or vac tubes

Awesome - I might try a small scale model of one of these as a fun project

I think the saturation inductor has an air gap too, just a bit thinner. With air gap you get sharper saturation effects, of course with lower initial inductance.... By the way the art of magnetic amplifiers is not completely forgotten. In a typical ATX computer power supply box you find an amplifier, which has only 2 terminals. Yes, an amplifier, with an input and output ports, but just two terminals overall. It is a current controlled PWM switch to regulate the 3.3V branch. Its construction? A toroid shaped core (the core is a coil of a thin strip of some metal, encased in a black plastic resin) with about dozen turns of a thick wire.

Best explanation

How did they ever figure out how to do that in 1965 ? Lots of math and physics smarts ? Or lots of trial and error ? Maybe both of those !

Simple yet ingenious

Good description!

I have a simular regulator, i don't use it of course, but my father did for the tv in the seventies.

If anyone is looking for one of these within USA check your local industrial controls shop for used industrial cabinets. Look for a beige transformer mounted to the outside with "SOLA" brand name. SOLA constant voltage transformer harmonic neutralized type CVS. These are used to protect the 120 v control power that supplies PLCs or larger motor drives. Can still be purchased new too. They work extremely well and last forever.

Constont voltage transformer (CVT) Grate video and amazing explain👍👍👍👌👌

Those are some chunky inductors and capacitors and nowadays they can fit 1KW stabilizers in half of that size!

Amazing technology 👍🏻👍🏻❤️❤️🙏🏻🙏🏻

Look ma, no transistors!

Bloody Heeeeeeeell !!!!! love it !!!!

Is that a Czechoslovakian variac? I have a very old ferroresonant inverter which was built back in the early '50s. It runs on 12V and can source up to 300 watts at 115VAC. It uses a mechanical chopper to drive the ferroresonant transformer. It was designed for powering radios and TV receivers.

Cool to see you still have the original receipts of that unit, looks like it was used in a photographer's studio -- perhaps to stabilize the output of the studio lamps?

Cool stuff back from the golden age

High output voltage than normal because one or all capacitors is out of spec. For 60 years old, it is still great though, much new ferroresonant voltage regulator output goes out of spec just 10 years of using.

What a fascinating device. I like the way the compensation winding is like adding an extra term to a Taylor series. Whoever invented this technique was a God-tier engineer.

Please test the sine wave purity and power factor under different loads. Thanks for very interesting content!

They: Than how does it work? Me: YOU FOOOOOL GERMAN ENGINEERING IS THE BEEEEST

I saw "ferroresonant" and my first thought was... sounds like an LC circuit in there. Isn't this basically a controlled shunt reactor? They use devices like these, albeit much, much bigger, in power transmission systems to stabilize line voltage and compensate for parasitic line capacitance.

This is better than EEvblog.

Fantastic

You are my IDOL....

Super film :)

Fascinating. I was expecting it to be filled with Annunaki ectoplasm.

we used them to regulate the supply to some philips high frequency T12 fluorescent lamp F48T12/CW/HO ALTO tubes

The 430 DM is _abzüglich_ or "after the discount". Hence the original price was around 575 DM or the equivalent of 1000~1200 €.

🙏🙏🙏👍Very simple and straightforward explaination with great graphic presentation.... If continued in another vid. would it be possible to see input current measurements..& p.f. @ rated range of I/p volts & at rated load/loads.. 👍🙏🙏..