Filament current draw quesiton.

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MGW
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Filament current draw quesiton.

Post by MGW »

I know the filaments for the tube compliment for an Express calculate out to 3.9 amps.

Technically a 4A filament supply is adequate, but is it really? Should I go for a trafo that can handle a bit more?
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JazzGuitarGimp
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Re: Filament current draw quesiton.

Post by JazzGuitarGimp »

A #44 pilot light bulb needs 0.25A, though I don't know if you've included it in your 3.9A calculation. I suspect most tranformer manufacturers hit the mark - if they say 4A, then you should be able to hum along all day at 4A. Would I overdesign by a bit? Yeah, I would, by maybe 10 to 15%.
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Firestorm
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Re: Filament current draw quesiton.

Post by Firestorm »

Cold filaments draw a huge amount of current until they get up to temperature. I assume the PT rating takes this into account, but I like to overrate the transformer anyway.
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MGW
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Re: Filament current draw quesiton.

Post by MGW »

The pilot is a 120v neon wired to the switch so it isn't a factor. Thanks for the input. I'll give it a little more wiggle room.
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