Building a transformer

In message , dated Tue, 8 Aug

That depends on how the leakage inductance is produced, and whether you can remove it, which you must in order to use it as a conventional transformer

I said it was silicon. The Ge device I used in HS was a Delco doorknob power device. I did 10W class-A ;-)

...Jim Thompson

They were, and were already pretty cheap. I used them at work in a big current regulator in '74 or '75.

John Perry

So......

F*ck man! Switch that s*it!

Nope, nothing else I can say without profanity.

SMPS, use a range of supplies, or just go SOL.

I mean, are you really planning on water cooling the maximum 600W you'll dissipate? Heatsinks that size can get pricey. Don't say it won't happen (the full dissipation).

Tim

I was only taking issue with your tense -- the 2N3055, while venerable, appears to be in current production. So it's an 'is' part, not a 'was' part.

Put a search in Ebay and store that page. Keep looking - odd and large transformers come up often, and go for quite reasonable prices. But what you want (roughly) is common on large audio power amps, so shouldn't be difficult to find.

Because of economies of scale buying the materials needed to make one will cost you much more than a factory - and that's without the time and difficulty involved.

Yup - Quad were using them in the 'late '60s in the 303.

What pray-tell is an RMS Watt? " Put out 400W RMS into 4 x 16 ohm speakers in parallel."

Sine wave into equivalent of 4 ohm load... 4 each 16 ohm speakers in parallel... I think... it was 30 years ago, might have been 4 each 8 ohm speakers... 2 ohm equivalent load. All I remember is the 400W ;-)

...Jim Thompson

Do you need both + and - power at the same time? If not, just have 0-50V would save you half the power. If you need to use 1V at 5A, your power supply would become pretty inefficient (supplying 5W and wasting > 300W). Are you planning to fan cool it? If not you need a huge heat sink.

If you use a switching design, it would be a lot more efficient.

A watt is a watt - a measure of power. So can't be qualified by RMS or whatever. Although that doesn't stop the advertising boyos trying...

I was just trying to distinguish the number from those that the "music power" types like to bandy around.

For instance peak instantaneous power would be 800W ;-)

...Jim Thompson

Get a copy of the 1980 book: Practical Transformer Design Handbook Eric Lowdon Howard W. Sams & Co. book publisher ISBN: 0-672-21657-4

I would need the option of both +v and -v in respect to ground, but only sometimes at the same time (ie when testing audio circuits, but not when doing logic circuits) if I switched one of the secondary windings off... would I still be saving half the power?

Wastage is becoming more apparent as I read more and more posts... and am considering rethinking to a more energy efficient design now.

I was (originally) thinking big heatsink with some thermal controlled fans screwed on.

switching psus I know nothing about, but think I will research this. Any good places to start (apart from the obvious google)?

Does nobody knows howto calculate transformers anymore?

this will be a 600Watt transformer

you will need iron of 150mm EEE and III (a standard dimension) a form of 50x54mm

primary: use 1.35mm diameter wire roll 377 spirals

secondary: use wire of 1.77mm diameter (if this does not exist, get the after next in diameter) weld first out line (60v) roll 104 spirals weld second out line (0v) roll 104 spirals weld third out line (60v)

put the irons one by one always alternate positions tight as much as you can the irons dive it into hot varnish and let it dry

this is just the transformer, i guess you will also want to pass AC to DC and maybe a voltage regulator controlled by a variable resistor, but that is another story ;)

regards ArameFarpado

Yea I know. That's very common in the audio industry but we Engineers should know better and use the proper terms. America is stupid enough without us adding to it, don't ya think?

I've run out of library shelf space, so I've been donating out of date books (like "Mother of All Windows" for Win95) to charity book sales ;-)

...Jim Thompson

It's in my GE handbook from 1973. ISTR some magazine article from 1971 using it, but I'm not going up in the attic dusting off that pile of old mags.

- YD.