Who makes their own OPT around here?
What core do you use?(type/material)
How to you wind the bobbin?
I haven't seen to much ppl around making their own opt. It's hard to get it perfect (audiophile grade) but most likely you can build a better one for a lot less than the price of commercial transformers.
What core do you use?(type/material)
How to you wind the bobbin?
I haven't seen to much ppl around making their own opt. It's hard to get it perfect (audiophile grade) but most likely you can build a better one for a lot less than the price of commercial transformers.
Not many people do it. The learning curve is steep, laminations of a proper size are hard to get, materials are expensive, etc.
There are some good tutorials out on the web and once I get a house and have the space to do this stuff I may give it a go - but I have no illusions of actually saving money by doing it.
There are some good tutorials out on the web and once I get a house and have the space to do this stuff I may give it a go - but I have no illusions of actually saving money by doing it.
It can be done, naturally. But on the other hand, aside from price, there are good transformer firms out there and some will wind to your spec (and of those, some will make the specific transformer part of the catalog afterward, since the design work is just sitting there, and they have the equipment to wind anything on order).
Unless you are a serious garage-rat hobbyist, or really want to learn the art, the truth is you may as well work another 10 hours and throw the wages at the problem instead. Time isn't money, but lost time is definitely lost forever. I can't see the exercise being a saving unless you're going into it whole hog; it might be different for someone already into it, since that's reaping the rewards of time invested. As a new venture the math changes, at least for me.
The exception might be if you need a huge, heavy piece of iron that costs way too much to ship, but even then you can always trade off delivery time for shipping cost. Even the proverbial "slow boat from China" eventually gets to it's destination. Also, the raw materials you might be able to get locally still have the shipping component in the price. Another possible exception is if you're building an "ultimate" amplifier that is worthy of the attention.
A well designed transformer that isn't built to a price is a wonderful thing, but they aren't cheap by their nature, even if you DIY it.
Unless you are a serious garage-rat hobbyist, or really want to learn the art, the truth is you may as well work another 10 hours and throw the wages at the problem instead. Time isn't money, but lost time is definitely lost forever. I can't see the exercise being a saving unless you're going into it whole hog; it might be different for someone already into it, since that's reaping the rewards of time invested. As a new venture the math changes, at least for me.
The exception might be if you need a huge, heavy piece of iron that costs way too much to ship, but even then you can always trade off delivery time for shipping cost. Even the proverbial "slow boat from China" eventually gets to it's destination. Also, the raw materials you might be able to get locally still have the shipping component in the price. Another possible exception is if you're building an "ultimate" amplifier that is worthy of the attention.
A well designed transformer that isn't built to a price is a wonderful thing, but they aren't cheap by their nature, even if you DIY it.
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When you tried winding a few OPT´s you´ll start apreciating the LOW price of the commercial ones.
A mains transformer takes me 1-2 hours to calculate and wind.
An OPT takes the best part of a day.
Only reason for winding one your self is if it´s so big you cant find one on the shelf or you want a special primary load or taps.
It can be done and there are a few good computer programs for calculating, but how you split the winding in sections and layers is an art i got a clue about how, but i´m not even close to mastering it.
And you need a winding machine doing it all by hand is almost impossible.
A mains transformer takes me 1-2 hours to calculate and wind.
An OPT takes the best part of a day.
Only reason for winding one your self is if it´s so big you cant find one on the shelf or you want a special primary load or taps.
It can be done and there are a few good computer programs for calculating, but how you split the winding in sections and layers is an art i got a clue about how, but i´m not even close to mastering it.
And you need a winding machine doing it all by hand is almost impossible.
I'm not making trafos (don't have any material and equipment to do so, and no reason to invest in this), instead, I design them for myself with my own software and order from any suitable factory (big headache indeed).
Use custom-made M4 toroid cores. Wanted to try HiB but factory I wished them to order from run out of this material and had no plan to purchase stock unless I place an order for 1 ton or so.
Use custom-made M4 toroid cores. Wanted to try HiB but factory I wished them to order from run out of this material and had no plan to purchase stock unless I place an order for 1 ton or so.
Well i know someone from who i can learn a few things.
About prices it all comes down to your sources
It depends where you are living. Russia and Ukraine are outside EU, and thus, customs may be a problem too expensive for small orders. Poland is an obvious choice.
I echo everything that has been said. I have wound a few of my own and the cost may seem small but it all adds up. Plus the amount of time involved is pretty extreme.
My first pair were rubbish and I was very disheartened by the whole affair, but since I had bought the materials I kept on and have had some pretty good results.
The cores I have been using are C-cores by thes guys:
Waasner
I got a huge load of transformers with these cores from an old(not that old really) current injection test rig from work, it was just dumped by the skips. Got almost 300Kg of cores from it
That is where I was lucky, if I had to buy core material it would be a no-go.
The first pair of trannys I built used the core kit cores readily available on ebay. They are ok but dont believe the "100W" nonsense that they peddle. Besides trannys are measured in VA so I was already on the back foot.
The rest is easy stuff, I make my own bobbins, with cheeks. some folks dont use side cheeks but I find it easier if they are there.
Next up is some kind of winding machine. I built a winder thinge using an old Smiths motor on a gearbox. Trouble is its a worm box so unwinding if I cross a turn is a pain.
If your intent on winding your own, go for it I did. Please be prepared to scrap your first ones though. Once you get the idea and it is not a black art at all, you will be away and anything is possible.
Cheers Matt.
My first pair were rubbish and I was very disheartened by the whole affair, but since I had bought the materials I kept on and have had some pretty good results.
The cores I have been using are C-cores by thes guys:
Waasner
I got a huge load of transformers with these cores from an old(not that old really) current injection test rig from work
, it was just dumped by the skips. Got almost 300Kg of cores from itThat is where I was lucky, if I had to buy core material it would be a no-go.
The first pair of trannys I built used the core kit cores readily available on ebay. They are ok but dont believe the "100W" nonsense that they peddle. Besides trannys are measured in VA so I was already on the back foot.
The rest is easy stuff, I make my own bobbins, with cheeks. some folks dont use side cheeks but I find it easier if they are there.
Next up is some kind of winding machine. I built a winder thinge using an old Smiths motor on a gearbox. Trouble is its a worm box so unwinding if I cross a turn is a pain.
If your intent on winding your own, go for it I did. Please be prepared to scrap your first ones though. Once you get the idea and it is not a black art at all, you will be away and anything is possible.
Cheers Matt.
Here is one of the best online tutorials on winding transformers, about halfway down the page:
education+diy
Read this site, check out the Radiotron Handbook and have at it.
Even if you don't wind your own, you can design it and tell your winder what you want done. I especially like his explanation of the use of cathode feedback windings.
education+diy
Read this site, check out the Radiotron Handbook and have at it.
Even if you don't wind your own, you can design it and tell your winder what you want done. I especially like his explanation of the use of cathode feedback windings.
Yves @ Dissident Audio. Has some software for calculating lams, layers etc.
He lurks here some days.
He lurks here some days.
Probably, Bud's one of the world's top transformer designers/ winders.
Power Transformers are pretty well understood, however Output Transformers are very tricky as all the the things that count towards a good power transformer are pretty much what you don't want in an output transformer.
My advice would be to do a search right here on diyaudio for threads on output tranformers or posts by BudP and I believe it will become pretty evident that this is one area that might be best left to the experts (did I actually say that?).
Best Regards,
TerryO
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power transformer are EASY. you can improvise alot and drop down the costs. you can take an 230-230 v transformer and just add a 6.3 v winding. 20 turns or something close. you can you an 220-110 transformer with a voltage doubler. or you can use diffrent transformers for B+ and filaments(best solution).
Back to opts. Let's talk about ciore materials and constructions.
Is it possible to use ferrite for HF in a multi way system? I've seen something related to this.
Back to opts. Let's talk about ciore materials and constructions.
Is it possible to use ferrite for HF in a multi way system? I've seen something related to this.
Nice, really nice
I like your method of terminating the windings.
Patrick's site is an absolute goldmine of information and is well worth a good read. I must say that the old Radiotron calculation for core area is a bit on the make it big side for modern core materials but if you use it you know you will get a good outcome
Cheers Matt.
, really niceI like your method of terminating the windings.
Patrick's site is an absolute goldmine of information and is well worth a good read. I must say that the old Radiotron calculation for core area is a bit on the make it big side for modern core materials but if you use it you know you will get a good outcome
Cheers Matt.
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