> Well here is what I don't understand PRR. If the transformer is rated for 200mA. then will it not be pumping out 200mA of current?
I have a 200 Amp fusebox, and presumably 200A worth of transformer out at the street. If I was really sucking 200 Amps, my electric bill would be $4,493/month.
Actually, I turn everything OFF, I use "no" power. And if I have just one 120 Watt lamp, or just 40 electric clocks, I pull just 1 Amp at 120V.
What the "200 Amps" means is: something bad will happen if I pull 201 amps. Somewhere near 500A for several hours, the street transformer overheats and goes boom. Perhaps 400A for an hour would make my feeder terminals burn off. To prevent this kind of excitement, I have 200A fuses which (are supposed to) trip-out at 400A for a few seconds or 220A for a few minutes.
But if I putter around with 1A lamps and 10A toasters and a 25A air conditioner, I never get near any 200A demand. I seem to average more like 5A.
(For a fusebox, over-sizing is fairly cheap. And some kinda safety against future demands... the A/C came 30 years after this fusebox, and we didn't have to think about it when we got the A/C.)
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You propose a PT rated 175V at 200mA load. If you actually connect a 201mA load, and it smokes, the maker won't listen to your complaint, altho you can probably run 250mA for years, getting something less than 175V. You can run it at zero mA, but the voltage will rise to maybe 200V. You can run it at 60mA and get something between 200V and 175V, with heat something between zero and full-load heat.
In today's market, you may "have" to take a 100mA or 200mA iron for a 60mA load. They don't make every possible spec.
> when EE people start going into that theoretical place is when I'm f*ked
Yeah, they do that too much.
The original wanted 175v-0-175V at 30ma and 6.3V at (IIRC) 1.05A. So for two, double each current: 60mA and 2.1A.
The original had one 5Y3 rectifier to make 30mA of DC. Can one 5Y3 supply 60mA? Yes. The voltage will be a hair lower, but I'm not concerned. The Am864u is not a precision limiter, you won't know the difference if B+ comes out 10V lower.
Anyway you won't find exactly 175V 60mA 6.3V 2.1A. You will probably have to buy something a bit bigger. It will be underloaded, so it will make a bit more voltage. If you are lucky, maybe just enough to counterbalance the drop from taking twice the current through the 5Y3.
While the math says 60mA and 2.1A, if you are "stuck" with a 100mA winding, the other can be nominal 2.0A. One is a bit underloaded, the other a hair over-loaded. If you don't get greedy, you can cheat a winding's rating 5% or 10% if other windings are 10% or more in excess of your needs.
If you want to be more discrete, really -separate- channels, you might indulge yourself with -two- 5Y3s. Then you not only need twice the 5V current, you need -two- heater windings (because on 5Y3 the heater/filament is also the B+ output, and you get no channel isolation if both are on one winding.) But you will find few irons with two 5V windings until you get to exotics which cost more than two small irons.