Desperate for some transformer advice!

[theundeadelvis]

Hey everybody,

A deadline is fast approaching for a little project of mine, and I am having trouble sourcing the proper transformer. I need one that goes from 120v primary to 9v 4VA8 secondary. I can't a suitable flat pack (or any other type for that matter), so I'm wondering if I could use a 9v AC wall wart and wire it to my PCB? Any help will be a life saver, so thanks a bunch in advance!

[edit]

May this Hammond work? http://www.philmore-datak.com/mc/Page%20259.pdf
It's 120v/9v 500ma, but I'm uncertain as to what the "VA" is? I'm not sure of the formula, but I think it should be 4.5va. Also, what would I do with the unneeded center tap? Just tape it off, or ground it?

[snap]

TR034 ? that would be 4.5VA. Do not connect the CT. Isolate it.

Strange thing you cannot find a flatpack. Maybe you can find a slightly bigger one, like  9V/0.67A (6VA).

[ClinchFX]

Just to expand on VA rating for the benefit of anyone who is not sure.

VA (Volt-Ampere) is defined as apparent power and, in a purely resistive circuit, such as an incandescent lamp or a heating element, is the same as true power (Watts).

For the purpose of transformer rating, it is the product of nominal secondary voltage and nominal secondary current.

For the Hammond TR034:

VA = 9V multiplied by 0.5A(500mA) -  note that current must be expressed in Amps.

Therefore VA = 9*0.5 = 4.5

Peter.

[theundeadelvis]

Thanks guys!

[puretube]

Do you need the "AC-part" of the xformer for your circuit too,
or does it only require the "DC" ?