6 ms·

Practical Transformer Winding (2010)

125 points by bearbin 5y ago

myself248 5y ago
Yesss! This is what I was hoping to find last time I clicked on an HN headline "transformers from scratch", which turned out to be about machine learning: https://news.ycombinator.com/item?id=29280909 https://news.ycombinator.com/item?id=29280909 This is great. It gets into the flux density and iron loss calculations that affect the physical size of a transformer core, choosing the wire, and then exquisite detail of actually winding and finishing the thing. I need to spend a bunch more time reading this site.
- formerly_proven 5y ago
  I find this trend of naming software ideas after common words really quite annoying (transformers, lenses, optics etc.)...
  - bob1029 5y ago
    I agree, but at the same time "Sequence-to-sequence model utilizing self-attention" doesn't roll off the tongue as well and would otherwise make the thing more difficult to talk about.
  - analog31 5y ago
    From what I've read, that's why physicists started giving things whimsical names like Quark, Charm, Strangeness, etc. The problem with using common words is that they always suggest an analogy, the analogy is never perfect, and often causes more confusion than understanding. (Also, Murray Gell-Mann was a whimsical character to begin with).
  - amelius 5y ago
    Or naming companies after physical units (e.g. Tesla).
    - codingdave 5y ago
      Or naming physical units after people (e.g. Tesla). FWIW, Tesla the company was named after Tesla the person, not the measurement.
      - dylan604 5y ago
        Yeah, the comment you replied is almost troll-like
        amelius 5y ago
        Why? Many professionals use the unit Tesla on a daily basis. It's like someone claiming the word Pixel for their company or product which I'm sure already happened.
        formerly_proven 5y ago
        https://store.google.com/category/phones https://store.google.com/category/phones
  - myself248 5y ago
    Or using the word "bandwidth" to refer to "capacity" or "data throughput" rather than "the width of the band that the signal occupies". Arrrrgh. Yes the two things are the same for certain naïve modulations, but the whole point of using a better modulation is that you get more throughput for the same bandwidth. Understanding this requires first unlearning the abuse of the term, and that's hard work for a lot of engineers who really need to understand this.
    - jbay808 5y ago
      Shannon's channel theorem states that the information capacity of a channel is directly related to the bandwidth and the signal-to-noise ratio, even if you use the best possible modulation scheme: https://en.m.wikipedia.org/wiki/Shannon%E2%80%93Hartley_theorem https://en.m.wikipedia.org/wiki/Shannon%E2%80%93Hartley_theo...
      - p1esk 5y ago
        He’s talking about throughput, not the information capacity of the channel.
        jbay808 5y ago
        Can you explain the difference? They seem to me like virtually the same concept, but you seem to see an important distinction.
        p1esk 5y ago
        Channel capacity is an ideal theoretical concept establishing a maximum data transmission rate over a channel with strong assumptions about the noise in that channel. Throughput is what you actually get in the real world, and it depends on many things, including a modulation scheme, retransmission protocols, specific noise models, etc.
        jbay808 5y ago
- priansh 5y ago
  Touché, I opened this hoping to find a new method to train Transformers and got the opposite
- belter 5y ago
  The Transformer Winding community knows that you won't let us down.
- scoot 5y ago
  A transformer and coil design guide from the same author: https://ludens.cl/Electron/Magnet.html https://ludens.cl/Electron/Magnet.html
aivisol 5y ago
Winding your own transformer was one of those things which amazed me as a teenager: you do a simple math by calculating winding ratio and the voltage is changed at the secondary by magic...
hwillis 5y ago
Ludens is absolutely legendary. This is part of his micro hydroelectric dam[1], which he uses to power his house, which he of course built himself. Far different, but if you enjoyed this you may also enjoy another classic (which does not have explanation), Claude Paillard making a vacuum tube from glass and metal: https://www.youtube.com/watch?v=EzyXMEpq4qw https://www.youtube.com/watch?v=EzyXMEpq4qw [1]: https://ludens.cl/paradise/turbine/turbine.html https://ludens.cl/paradise/turbine/turbine.html
- willis936 5y ago
  Incredible. I had a dream when I was a child of a house powered by small-scale hydroelectric, but learning the reality of water rights made me abandon it. It is truly inspiring to see someone live this dream.
VBprogrammer 5y ago
There are interesting people on thebackshed.net who have been building whole house inverters, initially repurposing some Chinese inverter chip but more recently an arduino for the brains. Unfortunately a lot of the info is spread across many different build threads but a big part of it is about rewinding toroidal transformers.
GnarfGnarf 5y ago
I ran a high school science lab in Bolivia in 1968. It was cheaper to get a local guy to hand-wind forty centre-tap transformers, than to order them from Germany or the U.S.
Isamu 5y ago
> Transformer steel is not all born alike. Manufacturers will provide data sheets about their products (often on their web sites), where you can see what they offer. There are usually many grades, with vastly different loss characteristics. At a given flux density and frequency, a good material might have ten times less loss than a cheap material! So it pays to look, investigate, and decide intelligently what to buy. Thinner sheets normally have lower loss, and the rest of the secret lies in the exact alloy. Okay this is what I come to HN for, thanks everybody!
londons_explore 5y ago
Nearly all usecases for a power transformer are now better served by a switched mode power supply. They tend to be much smaller, lighter, more efficient, cooler and cheaper. They also have features like adjustable output voltage, current limits, and overheat protection. Some can input and output AC or DC, at a configurable frequency and sometimes waveform. Some offer the same galvanic isolation that a transformer offers too. The core of a switched mode supply usually is a transformer, or at least an inductor, but the key difference is that it operates at far higher frequencies than classic uses of transformers, which allows them to be far far smaller, and therefore cheaper for the same power output.
- snowwindwaves 5y ago
  Are you saying large Transformers 1 mva, 10 mva, 100 mva, 500 mva are obsolete and should be replaced by switched mode power supplies? What mva is the threshold?
  - londons_explore 5y ago
    For new installation, yes, for any size a switched mode supply will usually be better in all dimensions. For the largest sizes, you can't buy them off the shelf, and there design costs may dominate. But after the thing is designed, in component costs, switched mode will win. Everything scales linearly with kVA, so there is no economics crossover point for the fundamental materials. Eventually it will be worth switching out old transformers - they contain a massive amount of valuable copper and quite valuable steel, and their lower efficiency means every year they remain in service they are wasting $$$'s of electricity. Transformers in cities can often be replaced with much smaller switched mode units underground, allowing the building housing the old transformer to be rebuilt as luxury flats to make the project much more profitable too!
    - snowwindwaves 5y ago
      Large power transformers have efficiencies in the 98-99.75% range. I don't doubt switch mode could be smaller and cheaper up to some size, but I am struggling to see transformers larger than about 5 mva being replaced with power electronics. Solar farms etc have inverters in modules I believe 500 kva each - and of course the power electronics are necessary there, there is no substitute. I have a 20 MVA transformer that is nearly at end of life and would be open to cheaper replacements.
bserge 5y ago
Christ, I still have a welder that I made myself. It uses a round ferromagnetic core I found in a scrapyard. I forgot how many windings it has, I think around 300 on the input side and 40 on the output. Wiring it was a major pain in the ass, as the core is round, a closed circle. And it draws too much current when idle, which means I have not used enough wire on the input side or the core is too small, fuck knows, I was 14 when I made it. It does weld well, especially on DC through 4 huge diodes I also found in some scrap. Sorry for my English, I'm drunk and tired.
Animats 5y ago
That's so retro. Useful if repairing boat-anchor equipment from the 1950s. Here's a more modern video on winding toroids by hand.[1] [1] https://youtu.be/sDIWNHOoNh8 https://youtu.be/sDIWNHOoNh8

125 points by bearbin 5y ago

Yesss! This is what I was hoping to find last time I clicked on an HN headline "transformers from scratch", which turned out to be about machine learning: https://news.ycombinator.com/item?id=29280909 https://news.ycombinator.com/item?id=29280909 This is great. It gets into the flux density and iron loss calculations that affect the physical size of a transformer core, choosing the wire, and then exquisite detail of actually winding and finishing the thing. I need to spend a bunch more time reading this site.

formerly_proven 5y ago
I find this trend of naming software ideas after common words really quite annoying (transformers, lenses, optics etc.)...
- bob1029 5y ago
  I agree, but at the same time "Sequence-to-sequence model utilizing self-attention" doesn't roll off the tongue as well and would otherwise make the thing more difficult to talk about.
- analog31 5y ago
  From what I've read, that's why physicists started giving things whimsical names like Quark, Charm, Strangeness, etc. The problem with using common words is that they always suggest an analogy, the analogy is never perfect, and often causes more confusion than understanding. (Also, Murray Gell-Mann was a whimsical character to begin with).
- amelius 5y ago
  Or naming companies after physical units (e.g. Tesla).
  - codingdave 5y ago
    Or naming physical units after people (e.g. Tesla). FWIW, Tesla the company was named after Tesla the person, not the measurement.
    - dylan604 5y ago
      Yeah, the comment you replied is almost troll-like
      - amelius 5y ago
        Why? Many professionals use the unit Tesla on a daily basis. It's like someone claiming the word Pixel for their company or product which I'm sure already happened.
        formerly_proven 5y ago
        https://store.google.com/category/phones https://store.google.com/category/phones
- myself248 5y ago
  Or using the word "bandwidth" to refer to "capacity" or "data throughput" rather than "the width of the band that the signal occupies". Arrrrgh. Yes the two things are the same for certain naïve modulations, but the whole point of using a better modulation is that you get more throughput for the same bandwidth. Understanding this requires first unlearning the abuse of the term, and that's hard work for a lot of engineers who really need to understand this.
  - jbay808 5y ago
    Shannon's channel theorem states that the information capacity of a channel is directly related to the bandwidth and the signal-to-noise ratio, even if you use the best possible modulation scheme: https://en.m.wikipedia.org/wiki/Shannon%E2%80%93Hartley_theorem https://en.m.wikipedia.org/wiki/Shannon%E2%80%93Hartley_theo...
    - p1esk 5y ago
      He’s talking about throughput, not the information capacity of the channel.
      - jbay808 5y ago
        Can you explain the difference? They seem to me like virtually the same concept, but you seem to see an important distinction.
        p1esk 5y ago
        Channel capacity is an ideal theoretical concept establishing a maximum data transmission rate over a channel with strong assumptions about the noise in that channel. Throughput is what you actually get in the real world, and it depends on many things, including a modulation scheme, retransmission protocols, specific noise models, etc.
        jbay808 5y ago
priansh 5y ago
Touché, I opened this hoping to find a new method to train Transformers and got the opposite
belter 5y ago
The Transformer Winding community knows that you won't let us down.
scoot 5y ago
A transformer and coil design guide from the same author: https://ludens.cl/Electron/Magnet.html https://ludens.cl/Electron/Magnet.html

aivisol 5y ago

Winding your own transformer was one of those things which amazed me as a teenager: you do a simple math by calculating winding ratio and the voltage is changed at the secondary by magic...

hwillis 5y ago

Ludens is absolutely legendary. This is part of his micro hydroelectric dam[1], which he uses to power his house, which he of course built himself. Far different, but if you enjoyed this you may also enjoy another classic (which does not have explanation), Claude Paillard making a vacuum tube from glass and metal: https://www.youtube.com/watch?v=EzyXMEpq4qw https://www.youtube.com/watch?v=EzyXMEpq4qw [1]: https://ludens.cl/paradise/turbine/turbine.html https://ludens.cl/paradise/turbine/turbine.html

willis936 5y ago
Incredible. I had a dream when I was a child of a house powered by small-scale hydroelectric, but learning the reality of water rights made me abandon it. It is truly inspiring to see someone live this dream.

VBprogrammer 5y ago

There are interesting people on thebackshed.net who have been building whole house inverters, initially repurposing some Chinese inverter chip but more recently an arduino for the brains. Unfortunately a lot of the info is spread across many different build threads but a big part of it is about rewinding toroidal transformers.

GnarfGnarf 5y ago

I ran a high school science lab in Bolivia in 1968. It was cheaper to get a local guy to hand-wind forty centre-tap transformers, than to order them from Germany or the U.S.

Isamu 5y ago

> Transformer steel is not all born alike. Manufacturers will provide data sheets about their products (often on their web sites), where you can see what they offer. There are usually many grades, with vastly different loss characteristics. At a given flux density and frequency, a good material might have ten times less loss than a cheap material! So it pays to look, investigate, and decide intelligently what to buy. Thinner sheets normally have lower loss, and the rest of the secret lies in the exact alloy. Okay this is what I come to HN for, thanks everybody!

londons_explore 5y ago

Nearly all usecases for a power transformer are now better served by a switched mode power supply. They tend to be much smaller, lighter, more efficient, cooler and cheaper. They also have features like adjustable output voltage, current limits, and overheat protection. Some can input and output AC or DC, at a configurable frequency and sometimes waveform. Some offer the same galvanic isolation that a transformer offers too. The core of a switched mode supply usually is a transformer, or at least an inductor, but the key difference is that it operates at far higher frequencies than classic uses of transformers, which allows them to be far far smaller, and therefore cheaper for the same power output.

snowwindwaves 5y ago
Are you saying large Transformers 1 mva, 10 mva, 100 mva, 500 mva are obsolete and should be replaced by switched mode power supplies? What mva is the threshold?
- londons_explore 5y ago
  For new installation, yes, for any size a switched mode supply will usually be better in all dimensions. For the largest sizes, you can't buy them off the shelf, and there design costs may dominate. But after the thing is designed, in component costs, switched mode will win. Everything scales linearly with kVA, so there is no economics crossover point for the fundamental materials. Eventually it will be worth switching out old transformers - they contain a massive amount of valuable copper and quite valuable steel, and their lower efficiency means every year they remain in service they are wasting $$$'s of electricity. Transformers in cities can often be replaced with much smaller switched mode units underground, allowing the building housing the old transformer to be rebuilt as luxury flats to make the project much more profitable too!
  - snowwindwaves 5y ago
    Large power transformers have efficiencies in the 98-99.75% range. I don't doubt switch mode could be smaller and cheaper up to some size, but I am struggling to see transformers larger than about 5 mva being replaced with power electronics. Solar farms etc have inverters in modules I believe 500 kva each - and of course the power electronics are necessary there, there is no substitute. I have a 20 MVA transformer that is nearly at end of life and would be open to cheaper replacements.

bserge 5y ago

Christ, I still have a welder that I made myself. It uses a round ferromagnetic core I found in a scrapyard. I forgot how many windings it has, I think around 300 on the input side and 40 on the output. Wiring it was a major pain in the ass, as the core is round, a closed circle. And it draws too much current when idle, which means I have not used enough wire on the input side or the core is too small, fuck knows, I was 14 when I made it. It does weld well, especially on DC through 4 huge diodes I also found in some scrap. Sorry for my English, I'm drunk and tired.

Animats 5y ago

That's so retro. Useful if repairing boat-anchor equipment from the 1950s. Here's a more modern video on winding toroids by hand.[1] [1] https://youtu.be/sDIWNHOoNh8 https://youtu.be/sDIWNHOoNh8