# relationship between core size and turns in transformer

Joined Jun 28, 2008
16
hi, friends i got a problem need ur help .
i have two cores of size 1.5 * 2 and 1.5 * 2.5 i am surprised how many turns i have to use for primary in 1.5*2 core and how many in 1.5 * 2.5
iron core. detail is
for 220 volts 50/60 hz
for 275 volts 50/60 hz
and for secndary 24 volts when using 220 primary winding

i realy want to know if core size changes then how turns changes is there any easy formula to determine turns and core size . i found 400 tuns for core size 1.5*2 and 350 turns for core 1.5*2.5 is it rite for primary windings
i will be very thankfull to u if u can solve my problem . thanks

#### SgtWookie

Joined Jul 17, 2007
22,210
Basically, the larger the core size, the more efficient it is. No, there isn't an easy formula.
Here is a good page to get a lot of information on how transformers work, and lots of transformer theory.
http://sound.westhost.com/xfmr.htm

#### John Luciani

Joined Apr 3, 2007
477
To determine inductance the formula is

N^2 = L / AL

N is the number of turns, L is the inductance, AL is the nominal core inductance that
is specified in the manufacturers datasheet. There is a lot of information about transformer
design at www.mag-inc.com

Your larger core has a larger cross sectional area (and larger AL) which reduces the
number of turns required to get the same inductance.

(* jcl *)

www.wiblocks.com