help me build an output transformer

[AudioGeek]

I am trying to increase my knowledge in transformers. One way is to try and use this forum and all the helpful folks.

My goal is to try and come up with an transformer design then build it myself.

My goal is to build a 1:1 output transformer. 100mH primary Inductance and 1 ohm or less primary resistance. probably bifilar wound and oh yes 3A dc primary current.

Is for a SS Class A amp... yeah i know its SS and this is a tube forum, but i thought that the transformer winders probably hang out here and not the SS one. lol.

I am looking for the process / steps to determine core size, number of turns, wire size, and gap size.

I will purchase the core from? and wire from? and wind myself.

Please anyone want to help me?

Thanks!

[Bandersnatch]

hey-Hey!!!,
Core laminations can be sourced from Thomas and Skinner. I got the tail end of a magnet wire spool to wind inductors for a turbo brake from Heyboer and I bet they'll also sell you some insulating material as well.
cheers,
Douglas

[AudioGeek]

cool thanks for info!

Do you have any hints or ideas for design?

[Bandersnatch]

hey-Hey!!!,
Get hold of Dave Slagle. He's got a neat magnetics simulator that I suspect you'll find very useful. As far as design goes...I have not given such things much thought. The 1:1 bi-filar ought to make the coil ridiculously simple I would think.
cheers,
Douglas

[LinuksGuru]

I written CAD transformer design software (TrafoWiz) for audio tube output amps, and now have a result - a pair of toroidal output units. I possibly can help, but the data you presented is not enough. There almost no data, in fact.

[AudioGeek]

ok, tell me what data you need. I will try to get the data.

Like i said this is a learning experience for me too, so bear with me.

thanks!

[GloBug]

....need more input.

[M Gregg]

Just for interest..


Dissident audio (I have no connection) do a O/P Tx calculator..
OPT Calucator

He is a member of this forum...

Regards
M. Gregg

[kevinkr]

Alpha-Core division of Bridgeport Magnetics Group, Inc.

Can get C cores here, good quality, reasonable prices, and small quantity orders.

[ChrisA]

Originally Posted by AudioGeek

I am trying to increase my knowledge in transformers. One way is to try and use this forum and all the helpful folks.

My goal is to try and come up with an transformer design then build it myself.

My goal is to build a 1:1 output transformer. 100mH primary Inductance and 1 ohm or less primary resistance. probably bifilar wound and oh yes 3A dc primary current.

Is for a SS Class A amp... yeah i know its SS and this is a tube forum, but i thought that the transformer winders probably hang out here and not the SS one. lol.

I am looking for the process / steps to determine core size, number of turns, wire size, and gap size.

I will purchase the core from? and wire from? and wind myself.

Please anyone want to help me?

Thanks!

Physically building the trandformer is a lot of work but given enough time and though and preparation and building some jigs you could do it

Designing one is harder and you should expect it to require more then one attempt. I don't think anyone builds a masterpeice on their first try.

The FIRST step is to aquire the equipment to skills to measure a transformer's performance.

At first you think designing a transformer is easy. Just remember that impedance ratio is the square root of the turns ratio. But there are many secondary effects such capacitance between the coils and also between wires in the same coil and leakage inductance. This is where the art comes in as you have to trade off one bad thing for another. No transformer can be perfect you you need to design the "least bad" one you can

I good reference you can download is the old "Radiotron" book. There is a chapter on transformer design. The author starts with a simple overview and cover design using just turns ration. Then he starts over but includes some other factors. It continues adding more and more secondary effects.

http://www.tubebooks.org/Books/RDH4.pdf

There are some more advanced books on transformers on the same web site tubebooks.org - Vintage info from the age of vacuum tubes