Transformer power formula Help???

[nhuwar]

I know there is a formula for finding the ball park approx. power throught put for a transfomer thats calculated by the core area does anyone happen to know it here????????

Please Help

Thanks

Nick

[jnb]

About a quarter of the way down this page
http://geek.scorpiorising.ca/windingtransformers.html
there is a chart that may help.

[lt cdr data]

2 other ways

rdh 4 says 2 ways you can do it, I can't remember precisely, but weight of core and core size dimensions.

I also saw a formula on the web that I haven't been able to find yet, I am looking and will update.

not much help for now...but have a look at rdh

[lt cdr data]

http://www.valveheart.com/theory/transformer.html

here....found it

[lt cdr data]

there is also another way, of course, look at commercial ones of the same application to get a good idea

trouble is, they can vary greatly, in terms of weight, I have seen se tx's suitable for 300b, go from around 1.7kg to around 6kg. that's about 3.5lbs to 14 lbs. big variation, but gives the scope. but that's for the whole tx.

the average, not mathematical, but most common, seem to be around 3.5kg, or about 6-7 lbs in weight.

its not too difficult to guess the core area if you know the size of the tx stack in situ for a commercial one, and hence power handling

[nhuwar]

Thanks for all the help.

Nick

[lt cdr data]

dunno if you saw the long equation from the site listed, he simplified it to the one on the 1st link

here is the longer one.

http://www.valveheart.com/theory/transform2.html

http://www.geofex.com/Article_Folder...es/xformer.htm

more info above

and patrick turner gave info on the rdh method/s, somewhere on his site, if you don't have/can't get rdh4.

4. Calculate the minimum required core cross sectional area, Afe,
for a nearly square core centre leg cross section.

Afe = 450 x sq.rtPO in sq.mm
**Note. This formula has been derived from a basic formula for
core size used for mains transformers, Afe = sq.root power input / 4.4
where the Afe is in sq inches. This ancient formula is based on signal ac B max being about
1 Tesla at 50Hz but we would want B max = approx 0.33 Tesla for an SE OPT.
After considerable trials the above formula is a good guide for SE audio OPT.