[sdiy] pc mount transformer Q.

[Tony Clark]

> there is a diagram like this
> 
>      1-----------\    /-------------5
>             )    (
>             )    (  
>             )    (
>             )    (
>      2-----------/     \----------- 6
>  
>      3-----------\    /-------------7
>             )    (
>             )    (  
>             )    (
>             )    (
>      4-----------/     \----------- 8
> 
> ok, for 115V it says to tie pins 1 to 3 and 2 to 4, apply (AC voltage?) to 
> pins 1 to 2 (no ideas why it says 'to' and not and between 1 & 2)

   That is correct, just parallel the two windings to give you full 115V 
power.  BTW, you _can_ use just one winding, but it'll only produce half 
the rated power output on the other side.

> it's got a series tie instruction, but I am after two 12V outputs, so I guess 
> that's paralell, which says to tie 5 to 7 and 6 to 8, and the parallel output 
> is on 6 TO 8.

   If you tie the two secondaries in series, then it becomes a center 
tapped design allowing you to get both +/- 12V out or just 24V out.  If 
you just want two separate 12V supplies, then leave the two windings 
separated!  You'll need to set up two bridge rectifiers and regulators 
and assundries however!

> I was figuring that I just apply the voltage to pins 1 &2 and pins 6 and 8 
> would each put out 12 VAC, and I figured I could just look for where ground 
> is with my DVM. does this sound right?

   There really isn't a ground on the secondary, the voltages induced 
there "float" unless you reference one side of the winding.  That's a 
good thing since you can literally short it out and it won't blow up!
   With two bridge rectifiers in place, just tie the two negative outputs 
together and that will become the ground.  Then the two positive outs 
will lead into individual filter caps and regulators.

> But since it is 115V AC, I figure it best to risk pestering you guys and 
> check so as not to blow myself up.

   That's always a good thing!  115V (or higher) always makes me a bit 
edgy!

   Good luck!

   Tony

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