If you mean winding your own toroidal power transformer, don't.
Instead, if you mean winding your own toriodal output transformer, don't.
Sorry to say, but this is probably one thing which you are almost definitly better off to purchase from a proper reputable company. Your time would be much better spent designing the circuitry and layout, or spending your money on better coupling capacitors and/or otherwise.
Adrian
Instead, if you mean winding your own toriodal output transformer, don't.
Sorry to say, but this is probably one thing which you are almost definitly better off to purchase from a proper reputable company. Your time would be much better spent designing the circuitry and layout, or spending your money on better coupling capacitors and/or otherwise.
Adrian
Thanks...I was afraid that that was the type of responses I would get! Does anyone know of any good dealers for transformers? Most of the companies that I have found on the internet don't seem to have what I'm looking for(or they're quite expensive). Oh, by the way,I was talking about power transformers. I found a company that has one for sale (surplus), and my idea was to re-wind the secondaries to accomplish my desired output. This is something that has always interested me, but maybe you're right, I should be spending my time learning more about amplifier design.
It is a good question, and I'd like to know too. I've seen two resources on hand rolled transformers of the three leg laminated variety, which for the most part agree with each other. I haven't seen anything (yet) on two leg types (but I haven't looked too hard for that). I've found a few services for custom toroids, but didn't see any of the math behind it.
Whaddya mean DON'T
Kiwi man -- oftentimes the only way to get the transformer you need is to roll your own -- this is particularly true from SMPS supplies for which inductance, leakage are important. But generally, if analyzing the problem as time = money, it's easier to just pull what you need from a catalog.
But, it's not that difficult. If you think of the "shuttle" used in weaving, you fashion one which will slip in the donut hole and you're good to go.
At any rate, I am blue in the face from recommending the ARRL handbook in these matters. They have a SMPS design with excellent directions for winding a multilayer torroidal transformer for a high power transceiver supply.
Kiwi man -- oftentimes the only way to get the transformer you need is to roll your own -- this is particularly true from SMPS supplies for which inductance, leakage are important. But generally, if analyzing the problem as time = money, it's easier to just pull what you need from a catalog.
But, it's not that difficult. If you think of the "shuttle" used in weaving, you fashion one which will slip in the donut hole and you're good to go.
At any rate, I am blue in the face from recommending the ARRL handbook in these matters. They have a SMPS design with excellent directions for winding a multilayer torroidal transformer for a high power transceiver supply.
If it is not absolutely necessary to have a toroid, it should be
considerably simpler to wind an ordinary EI-core transformer.
I have seen kits sold here in Sweden where the primary is
factory wound and you do the secondaries yourself. This should
be much simpler since you assemble the core after winding.
considerably simpler to wind an ordinary EI-core transformer.
I have seen kits sold here in Sweden where the primary is
factory wound and you do the secondaries yourself. This should
be much simpler since you assemble the core after winding.
Toroid Corp of Maryland (http://www.toroid.com) sells power transformer kits. The 80 VA kit for example is $27 and comes with the primary and thermal breaker already installed. Wind on your secondaries, add leads to the secondaries, wind the finishing tape and you are done.
I have done this with good results a number of times. For a description of the transformer I use with my TubeDAC, take a look here:
http://quadesl.com/pdf/trans_inst.pdf
Now, having said that, I'll also say that it's a real pain. Low voltage windings like heaters or IC type levels, are fairly easy wth something like 40 turns. but a tube B+ with like 1500 turns is laborious, thumb muscle cramping work. But I've built some very complex transformers with many taps that would cost several hundred dollars for a custom unit (or you'd be using many descrete transformers). The TubeDAC transformer has a center tapped +-15 volt pair of windings for digital chips an idential pair of windings for analog chips, it's got two idenital heater windings that can be put in series or parallel for differnet output tubes. It's also got a 250 volt B+ winding. I put all that together for about $50. And I've still got a bunch of magnet wire left over for other transformer winding needs.
Sheldon
I have done this with good results a number of times. For a description of the transformer I use with my TubeDAC, take a look here:
http://quadesl.com/pdf/trans_inst.pdf
Now, having said that, I'll also say that it's a real pain. Low voltage windings like heaters or IC type levels, are fairly easy wth something like 40 turns. but a tube B+ with like 1500 turns is laborious, thumb muscle cramping work. But I've built some very complex transformers with many taps that would cost several hundred dollars for a custom unit (or you'd be using many descrete transformers). The TubeDAC transformer has a center tapped +-15 volt pair of windings for digital chips an idential pair of windings for analog chips, it's got two idenital heater windings that can be put in series or parallel for differnet output tubes. It's also got a 250 volt B+ winding. I put all that together for about $50. And I've still got a bunch of magnet wire left over for other transformer winding needs.
Sheldon
Re: Whaddya mean DON'T
Agreed! Keep in mind that for SMPS transformers you usually deal with less than 2 dozen turns. For a 60Hz transformer, you need many many more turns. So, if you plan on building a SMPS transformer, winding it yourself is the only way to go. If you plan on a 60Hz transformer, You may not want to spend the time.
(In all honesty, I have several transformers collected because they are a EI cores with screws holding the laminations together. I'm keeping them just so I can wind a 60Hz transformer when I need a custom unit!)
-Dan
jackinnj said:
Agreed! Keep in mind that for SMPS transformers you usually deal with less than 2 dozen turns. For a 60Hz transformer, you need many many more turns. So, if you plan on building a SMPS transformer, winding it yourself is the only way to go. If you plan on a 60Hz transformer, You may not want to spend the time.
(In all honesty, I have several transformers collected because they are a EI cores with screws holding the laminations together. I'm keeping them just so I can wind a 60Hz transformer when I need a custom unit!)
-Dan
but have you ever cooked a transformer?
to loosen the laminations? of course they all must remain isolated.
Nat Semi and others give you the primary inductance from their switcher software which is a big help. An impedance bridge or LCR meter is a necessity to calculate the minimum impedance.
to loosen the laminations? of course they all must remain isolated.
Nat Semi and others give you the primary inductance from their switcher software which is a big help. An impedance bridge or LCR meter is a necessity to calculate the minimum impedance.
i used to work for a comopany that made power transformers. I hate to say it, but the bigger toroids were mostly hand made.. a machine wrapped up enough wire for each winding on a H shaped piece that could go through the center of the ferrite ring, and then a minimum wager wrapped it around and a round. For the smaller torroids, and all other laminate and filters and such there were bobbin winding machines that pretty much did it all. Soi it is very diy-able, its just time consuming as hell
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miguel2 said:I have this 800 VA 220 primary, 47-0-47 secondary toroidal transformer. It gives 65-0-65V after the bridge. As I only need 50V can I unwind some coils? It also buzzes a bit, even when at no load. Is there anything I can do to fix this?
Thanks.
Yes, you should be able to remove some windings to lower the voltage. Be sure to remove an equal number of winding from each side to maintain the same plus and minus output voltage.
Humming is generally due to mechanical resonances and can be difficult to eliminate. Be sure to fasten it down snugly to the chassis. Another coat of varnish might help, too. Hopefully others can some some other suggestions.
Winding your own power toroid transformer.
If your are still interested in winding your own transformers, try Toroid Corporation of Maryland a 9001 company. http://www.toroid.com/standard_transformers/transformer_kits/tr...
If your are still interested in winding your own transformers, try Toroid Corporation of Maryland a 9001 company. http://www.toroid.com/standard_transformers/transformer_kits/tr...
I got a toroid kit once from them. I was pissed, it did require a bit of work as the laminations were not mechanically fastened very well and buzzed. I was pissed because I had to re-build it. I used JB weld to glue the laminations back together. Then a layer of Teflon, and then the polypropylene film insulation for proper isolation. Because it is 1.4KVA and has 120VAC primary, the primary winding is 10ga wire, not the easiest wire to work with. In the end, I do have a very large bench transformer that makes very little noise, however, all large toroids will buzz due to line noise or asymmetrical line voltage. For example, if a microwave oven is on the same circuit, it will take more energy from one half of the mains waveform than the other. The large toroid is sure to buzz from this. After I re-built this one, it dawned on me I may add more primary turns to decrease the flux density, so the core will not be operating at it’s maximum flux excursion, just to add a little wiggle room. If the VA is large enough, should be no big deal to loose a little B or loose some volts/turn. This transformer has about 0.83V/turn for the secondary windings.
If the VA is large enough, should be no big deal to loose a little B or loose some volts/turn. This transformer has about 0.83V/turn for the secondary windings.Attachments
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