Sorry, I didn't get the notification that any answer had been posted which is really weird.
The -2V in my calculation was a generous estimation for the voltage lost over the diodes, as to the voltage in my home, just now I measured 234V with my DMM. I have had the intentions to design a device that would be put in the wall socket to be left there for a year or two in order to plot and analyze the actual voltage fluctuations, but I have forgotten about that. I feel it to be a surprisingly exciting project to do but having done a few measurements(something like 5 times over 24 hours) manually seems to indicate that my mains voltage is pretty stable, apart from that day of those 5 measurements I might have measured the mains about 10 times over the last 2 years and every time the result have been the same. I haven't actually measured any variation at all, it's always 234VAC.
In Sweden we have a 230VAC nominal voltage amplitude that is allowed to vary by +5%/-10%, actually the specification says that the voltage has to be within 207VAC and 244VAC which is +6%/-10%.
But I live quite near one of our largest power plants and there are a few industrial district in my town, which I theories means that I live in one of more stable areas. I read something saying something akin to stability is related amongst other things to how many users there are related to the area of land, so if you live far out in the bush you probably won't have as stable voltage supply as I have who live in one of our largest city's.
So it would seem as 234VAC is a pretty constant value, and the transformers are mad for 230VAC, take a look.
Hahn EI541 1128:
Power = 16VA
Secondary(s) = 6VAC(2x)
Output current = 2x1333A
Primary = 1x230VAC, 50-60Hz ±10%
Hahn EI541 1129:
Power = 16VA
Secondary(s) = 7,5VAC(2x)
Output current = 2x1070A
Primary = 1x230VAC, 50-60Hz ±10%
So there isn't really any choice here, the 7,5VAC with its 1,07A output current isn't sufficient.
This will work because this is for a power supply for my LCRZ-meter project that have been discussed in another thread and I have wished to enable a ±5V@±1A excitation signal(that is it's absolute maximum values), but I would not consider the design a failure if it didn't reach quite that current. But since I have set that goal that is what I'll design for.
The other circuits in the LCRZ-meter design doesn't need many mA at all, 0,333A will definitely suffice(meaning there are a margin), I would have liked a larger margin(thank you for telling me that, I know that I always should add margins but it does slips my mind more often than I'd like) but I'll consider the excitation signal current as a spare reserve that will have to act as the margin if needed be, by assuming that the full ±1A will never be reached completely.
The transformer is on sale you see so I'll go with that, I will when I have accomplished the objectives of the LCRZ-meter design design a version with a revised power supply anyway, I really want to end up with a battery driven device with a LCD to be optionally used stand alone as opposed to in conjunction with Matlab.
As for the circuit, here it is:
I've added the first pair of inductors as an just in case measure, those inductors footprints will be easily shorted. though I haven't picked out the values for them.
As for the output inductor of the negative regulator, it looks like a pi filter but may I use the regulators output cap as the first cap in a pi filter?
The negative regulator is much noisier than the positive regulator.