need to build a transformer.... point me in right direction?

[AudioGeek]

hey,

I am looking to build a simple transformer with 2 primary windings and one secondary winding.

ratio of 1:2 for primary 1 and 1:2 for primary 2...

so essentially quadfilar wound i guess?

oh an no DC on core.. actually there will be DC but the second primary winding is there to null or offset the DC...

make sense?

problem is, what core size, what wire thickness, and how many total turns?

any primers out there? or anyone can help me?

oh... this is all like less than 10v on these transformers. for a pre-amp.

Thanks!!!

 

[AndrewT]

Hi,
I have just re-read your Q.
I do not know what you intend doing with the result.
Is it mains frequency or audio frequency?
Is power or driver?
What power/current/impedance do you expect.
I will not be able to answer your Q but do try to give your potential respondents a chance.
regards Andrew T.

 

[jacco vermeulen]

You can always read a book on transformers.
Menno vanderVeen has written one, you can find his stuff at the Plitron site.

 

[Eva]

These three sentences may help you to better understand transformers :

- For a given core and keeping the frequency constant : The number of primary turns is proportional to the maximum voltage it has to withstand without saturating

- For a given core and keeping the voltage constant : The number of primary turns is proportional to the inverse of the minimum frequency it has to withstan without saturating [1/F]

- Keeping the voltage and the frequency constant, the minimum number of primary turns required to avoid saturation decreases as core size is increased

So essentially you have to find a core size that allows a reasonable minimum primary turn count for your minimum frequency and maximum voltage requirements

You may also think in terms of :
max.voltage / (frequency * turns) = constant

[And this constant increases with core size. Note that the voltage capability increases with frequency]

Note that this is a drastic simplification, there are a lot of parameters to consider in transformer design