I've been thinking that it would be fun to go through the process of designing and building a pair of 5k push-pull output transformers, to be driven by a pair of 40W beam tubes. I've read through Patrick Turner's website and I'm sure that there are a more than a few good people here on this forum that I could come to with questions. I think I could get to a workable design and maybe if I'm lucky, a design that even works well.
My main concern is buying parts I would need. Most of the parts don't seem easy to buy in small quantities. Are there places to buy cores and wire in those quantities? I've come across Brideport Magnetics in my searches, anybody ever order from them? Or any other places?
I don't expect that I'd save money over buying a pair of good transformers. I don't care about the money. This is more about having a learning experience.
My main concern is buying parts I would need. Most of the parts don't seem easy to buy in small quantities. Are there places to buy cores and wire in those quantities? I've come across Brideport Magnetics in my searches, anybody ever order from them? Or any other places?
I don't expect that I'd save money over buying a pair of good transformers. I don't care about the money. This is more about having a learning experience.
I have ordered from bridge port. They actually have pretty good stuff. Edcor would also sell you laminations.
There is also a book on diy transformer winding. It's pricey, but it's worth it.
https://www.amazon.com/Transformers...lpcontext&ref_=fplfs&psc=1&smid=ATVPDKIKX0DER
There is also a book on diy transformer winding. It's pricey, but it's worth it.
https://www.amazon.com/Transformers...lpcontext&ref_=fplfs&psc=1&smid=ATVPDKIKX0DER
It can be fun winding a few transformers, but looking and acquiring the needed materials on a small DIY scale is not so fun.
For small scale you could do it by hand, but for big batches you need a machine and tensioners.
Transformer knowledge is scattered in small pieces of info all around the internet, you need to search a lot and bring the pieces together.
For small scale you could do it by hand, but for big batches you need a machine and tensioners.
Transformer knowledge is scattered in small pieces of info all around the internet, you need to search a lot and bring the pieces together.
Hmmmmmmm.......... Bridgeport.
https://www.bridgeportmagnetics.com/bmg-product/__trashed-2/
I only knew of them as AlphaCore, I have always suggested and promoted that company when wanted to get some cores from them to wind myself a few ESL transformers !!
I actually started on quite a few recipes and started writing a toroid transformer calculator by using their specs and tests on my own cores, but I never did get around to ordering some. :/
I am So Glad to see that they are still around, I guess I better get some stuff ordered before they disappear like many other Great American companies.
This is the only company that I know of over here where you can get raw cores, Cheap (Reasonably) !!
I know of only one other company that offers Kit Cores with Ac Line primaries already wound on them, custom voltages cost much more from them as well and I forget the name of the company, but they are still around as of a few years ago too.
I already talked to all those guys in past years in research of the subject.
Do Let us know if you get some, I am most interested in them as well, at least these days I can afford to get some now as in past years I was not able to get even one to try out, I am so glad to see them still around.
Cheers !! 🙂
jer 🙂
https://www.bridgeportmagnetics.com/bmg-product/__trashed-2/
I only knew of them as AlphaCore, I have always suggested and promoted that company when wanted to get some cores from them to wind myself a few ESL transformers !!
I actually started on quite a few recipes and started writing a toroid transformer calculator by using their specs and tests on my own cores, but I never did get around to ordering some. :/
I am So Glad to see that they are still around, I guess I better get some stuff ordered before they disappear like many other Great American companies.
This is the only company that I know of over here where you can get raw cores, Cheap (Reasonably) !!
I know of only one other company that offers Kit Cores with Ac Line primaries already wound on them, custom voltages cost much more from them as well and I forget the name of the company, but they are still around as of a few years ago too.
I already talked to all those guys in past years in research of the subject.
Do Let us know if you get some, I am most interested in them as well, at least these days I can afford to get some now as in past years I was not able to get even one to try out, I am so glad to see them still around.
Cheers !! 🙂
jer 🙂
I used a kit from Toriod inc. https://toroid.com/transformer-kits/ It comes with the primary already would. The instructions are pretty good.
I made one for my DAC 8 years ago and its still working perfectly.
I made one for my DAC 8 years ago and its still working perfectly.
That is on my radar:
http://www.ukcnc.net/index.php/products/200mm-coil-winder/
I just don't have the space at the moment.
http://www.ukcnc.net/index.php/products/200mm-coil-winder/
I just don't have the space at the moment.
Youtube has some winders showing the craft. I'd be interested in just learning the craft alone, let somebody else do the math! If one masters the craft and materials and tools, starting out with power transformers then working up to OPT's. I would imagine the journey would cost money, time and mistakes, but hard to do things are valuable things.
This one is pretty relaxing to watch.
This one is pretty relaxing to watch.
Many here know that I learned electronics by building and blowing up DIY tube amps made with parts from discarded radios and TV's. In the early days everything used tubes. By the mid 60's magazines like Popular Electronics teased us with DIY builds using transistors. The earliest one I wanted to build was the SWTPC Lil Tiger , but the kit was beyond the budget of a 14 year old kid. I did save enough money for the semiconductors and built one channel for a guitar amp using a series parallel combination of Radio Shack and other filament transformers for power. The amp worked, the kluged power supply did not. What to do now? I got the power transformer from an old B&W TV set, used a hammer to loosen up and remove the laminations, and ripped off all the secondaries leaving the original primary winding intact. The bobbins in those days were paper so one must be careful not to destroy it. had counted the turns on the heater windings to find the turns per volt, then multiplied that number to find the secondary turns needed for my target voltage. I wound a new secondary using ordinary masking tape for insulation. Then I reassembled the transformer.
I never expected this thing to work at all, but it not only worked, it was still working over 30 years later.
In order to keep my title as having the most powerful DIY guitar amplifier in my high school electronics, I built this power amp stage in 1969. It used the totem pole circuit that was common at the time in HiFi amps. This circuit requires a driver transformer, so I wound my own on the core of a fried Radio Shack filament transformer. This amp was driven with a 5 watt tube amp and put out somewhere between 250 and 350 watts into a 4 ohm load. It used 6 X mystery transistors that I got from a local surplus store for 25 cents each. The amp was used to drive eight 10 inch speakers very loudly for several years. It wound up tossed in storage in 1974 when I left home never to see power again. A hurricane in late 2006 destroyed the shed that the amp was stored in, which was just covered with a tarp for about a year. Sometime in late 2007 I found the amp in the rubble. I plugged it in just to see what would happen, and after bypassing the fuse I got the expected venting power supply caps. I kept the heat sinks with transistors and trashed the rest, but I took the DIY masking tape driver transformer apart to see how it fared.
The transformer was quite rusty from life in a leaky shed in south Florida, but reasonably clean inside. The adhesive on the tape had lost its stick, and the paper was quite brittle, but the transformer would have worked fine if left undisturbed.
The output stage schematic is from an old (1960's) RCA transistor manual. I used this circuit with NPN silicon transistors on about 105 volts of B+.
I used this technique many times over the years, but it was far less successful with vacuum tube OPT's. I still have a box full of failed OPT experiments around here somewhere.
Later on I switched to plumbing Teflon tape, then later Kapton tape for power transformers for better insulation. These materials have a far higher dielectric constant than paper so their use will increase the stray capacitances which is not desirable in an audio application.
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For one-offs a simple hand cranked winder is good enough, it only takes patience.
I have one for prototypes or extremely thick wire where my auto-winder feels stressed.
I have one for prototypes or extremely thick wire where my auto-winder feels stressed.
I have ordered laminations from Thomas-Skinner. https://thomas-skinner.com/transformer-laminations/
They are pretty reasonable and their minimum is not too huge, usually 90-100 pounds.
I order wire from amazon, or even ebay. Just be sure it's double enameled with high temperature polyester-imide enamel.
Bobbins are all over the place. I've even ordered them from India, for one of Patrick Turner's monsters.
I have built output transformers, power transformers, and chokes, following Patrick Turner's guidelines. He was old-school and did not waver from the classic techniques. His transformer are big! It took me a while to figure out what he was writing in his transformer pages, but once it clicked, I was really impressed. He put in an insane amount of work developing his method. I did an excel spreadsheet to implement exactly his design technique.
I think it is well worth it to build some output transformers following his technique. It is incredibly educational.
You can probably find quite a bit of it in the Radiotron Designer's Handbook, 4th edition (RDH4). I seem to recall that Pete Millett has a copy of that online: http://www.tubebooks.org
Tom
Ok, it looks like all of the materials would be obtainable by shopping around.
I would need to build a hand crank setup to wind. Seems doable.
The last thing I'm thinking about is the varnish. Patrick Turner's method was painting with a brush as he wound. Is it also possible to dry wind and then use a vacuum chamber to varnish as a last step? That sounds preferable to me.
I would need to build a hand crank setup to wind. Seems doable.
The last thing I'm thinking about is the varnish. Patrick Turner's method was painting with a brush as he wound. Is it also possible to dry wind and then use a vacuum chamber to varnish as a last step? That sounds preferable to me.
Use a small motor, with pulleys or bicycle chain wheels to reduce speed, better than hand cranking, less speed variation, meaning better tension control, better winding.
Motor winders here use varnish applied with a paint brush to the coils, and then a filament bulb, about 60-100 W, depending on motor, to dry it out, especially in the rainy season.
This is done after putting the coils inside the stator.
They use mechanical counters to see how many turns, those are cheap, useful to have around.
You can dunk the whole thing in varnish, preferably on load, and remove to dry, over a bucket or news paper.
Humming on load allows the varnish to penetrate properly....more durable result.
Motor winders here use varnish applied with a paint brush to the coils, and then a filament bulb, about 60-100 W, depending on motor, to dry it out, especially in the rainy season.
This is done after putting the coils inside the stator.
They use mechanical counters to see how many turns, those are cheap, useful to have around.
You can dunk the whole thing in varnish, preferably on load, and remove to dry, over a bucket or news paper.
Humming on load allows the varnish to penetrate properly....more durable result.
I built this coil winder for a project but never got around to actually using it. Found a nice brushless motor with a gearbox attached. It has hall sensors and an encoder but fortunately driver boards are cheap on eBay. I used this as an excuse to write some arduino code to count turns using the sensors. You can find cheap little foot pedals that give a 0-5v signal to control the speed.
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Read through these thread's as a start to find your DIY core's unknown parameters of any size, This link it to a post of the two main links of all of that I went on, and on other threads of more on testing of the Antek cores at the time using the same methods,
https://www.diyaudio.com/community/threads/transformer-saturation-effect.370415/post-6601209
With this info ( if you can get thorough my bad typing 🙂 ), you can determine your individual cores Volts per Turn per Frequency, easily with a simple small decent amp and a voltmeter and or scope works best, I did all of this and more just using my sound card and/or Signal generator and meter / or scope as well, and went on to find the each of the winding's parasitic capacitances and of core FR, THD and Impedance graphs as well as leakage inductance all with a sound card mostly and a small clean amp to drive the core with.
FWIW. 😉
jer 🙂
https://www.diyaudio.com/community/threads/transformer-saturation-effect.370415/post-6601209
With this info ( if you can get thorough my bad typing 🙂 ), you can determine your individual cores Volts per Turn per Frequency, easily with a simple small decent amp and a voltmeter and or scope works best, I did all of this and more just using my sound card and/or Signal generator and meter / or scope as well, and went on to find the each of the winding's parasitic capacitances and of core FR, THD and Impedance graphs as well as leakage inductance all with a sound card mostly and a small clean amp to drive the core with.
FWIW. 😉
jer 🙂
Use an arduino or other small computer and automate it with steper motors. I built a coil winder and did a pair of 71A OPTs for a headphone amp driving 300Ohm headphones. It was fun and worked quite well. That said, 5K to 8 Ohm has a lot more challenges for interwinding capacitance. Start with something simple and work up.
As for the winder, probably cheaper to buy one : https://www.aliexpress.com/i/32882288707.html
You can add one or more counter and sensor if you have to do more than one winding at the same time (interleave winding for example).
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