What are the options best options for obtaining a small (5-15VA) toroidal power transformer with 115-0-115 primary having either 100 Ohms or 25 Ohms resistance per winding?
So I can then derive 50O Ohms in series or parallel.
Secondary voltage doesn't matter.
Paul Witlon
"Paul Witlon"
** Very odd question.A typical 15VA transformer ( 240 volt, 50Hz ) has a primary resistance of around 250 ohms - this drops to around 180 ohms for a 20 VA type.
A 50VA type would have two windings of about 25 to 30 ohms.
Farnell sell two brands of toroidal trannies in 15VA and 50VA with split primaries and various secondaries - for some strange reason, primary resistance is almost never specified by transformer makers.
..... Phil
Why?
John
** Must intend feeding it from a run of 50 ohm co-ax .......
.... Phil
Sorry, that was a typo. Should have been _50_ Ohms.
Anyway the 7 mAH from RS looks about right if I parallel the windings.
Many thanks,
Paul Winton.
"Paul Witlon"
** Crikey: it is a 7VA unit - pal. ** You have seriously misread the data.That tranny has a single primary winding with a tapping at the mid point.
So it CANNOT be paralleled or there will be a massive short.
There is no way to get close to 50 ohms either.
What planet are you on ??????
.... Phil
7 mAH? That doesn't make sense as a spec for a transformer. If you tell us what you're trying to do, we'd be in a much better position to help.
Unless you're quite experienced in electronics and are sure of what you're doing, you could be using a completely wrong approach to achieve what you want.
A tiny battery might be rated at 7mAH, but not a transformer, another typo?
That is a hell of a lot of turns of small wire - which most likely would not fit on the presumed "small" toroid.
...in which case there will be a bandwidth problem.
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