Help required withtransformer impedance, and turns ratio. .

Dear All,

Please forgive me if you think this question is a trifle simple, but I would love somone to explain why a transformer that has a turns ratio, and hence(?) voltage gain of 1:2 is 150 Ohms: 600 Ohms, and not 300 Ohms:600 Ohms . . . Also, why doesn;t the impedance halve when coils are in parallel? I am sure that someone can direct to me to some worthy tome, but my (frequent!) Google searches reveal nothing I can get my teeth into. Please can someone help!

All the best,

ANdyP

A lossless transformer conserves energy. Power in is at most power out. Power is proportional to the square of voltage or the square of current; for the same voltage power is reciprocally proportional to impedance.

Since the voltages are as the ratio of numbers of turns, and the currents as as the reciprocal ratio of turns, the impedances are in the ratio of the squares of numbers of turns, and eveybody is satisfied :grin:

When you have two identical coils in parallel in the same core, you just have the same number of turns throught the same core, so the same impedance, but the resistance will be half... You are driving the same core. You won´t need more power to drive two coils in paralell if they are in the same core, so impedance will be the same. Source impedance will vari very very little, because of the lower winding resistance in series with the source, but if you are driving the coil with a reasonable source impedance, it should be negligible.

If you have two coils in parallel but those are in two diferent cores, then you will have 1/4th of the winding impedance, and you will need more power to drive the two coils.

Energy is neither created nor destroyed.

If voltage goes up by 2, current must go down by 2. Stick that in your Ohms Law and see what you get.

shouldn´t write at the same time as bcarso and PRR

Gentlemen,

You are just that! Thank you! - Power . . . . now I get it!

So to follow on, if you build an ms matrix with transformers, what should the ratio be to either split or combine? 1:0.5+0.5, or 1:0.7+0.7? ie, is it power or voltage that is important?

Or am I barking up the wrong tree?

Woof woof,


ANdyP

1: .7

The way I like to remember it is that inductance is a function of turns squared. Impedance relates to inductance in a linear way, so you could say that for a fixed frequency, impedance is a function of turns squared.

So if your turns ratio is given, you impedance ratio is also.
Or you can get the turns ratio from the imp ratio.
Either way.
Save and print, or whatever.

bcarso, PRR, CJ...

Strange&bouncy, you're receiving hallowed attention! :wink:

Keeef

What, Steve's in the house?

Iron is a big subject here :grin:
:guinness:

Ever hear "Big Iron on His Hip" by Marty Robbins?
He was talking about a Lundahl 1538 XL! :grin:

Iron Maiden are big Lundahl fans, too

Thanks, Guys,

Keeef, I am indeed deeply touched by all this attention. Not to mention greatly "better informed". - More Knowledge Acrued per square inch HERE than Anywhere Else! - I have really learnt a lot from this posting, not only the direct answer(s) to my question, but also that is that it is CRUCIAL that you do not ask a stupid question in a dumb way! Exercise those little grey cells, and you will be rewarded! Thank you again for your indulgence, Guys.

:green: :green: :green:


A very happy-and-well-informed ANdyP!