Re: Egg of Columbus Progress

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Original poster: "Christoph Bohr" <cb@xxxxxxxxxxxxxxx>

Hello Cameron.

> Speaking of wire, I'm thinking about using 12 AWG. I am not sure about the
> amount of turns. My guess is it's going to be a trial and error kind of
> thing.
only one try, no errors needed ;-)
just wind some turns of scrap wire on the core, feed the coil with a variac
and check for incresing current at some voltage when the core saturates.
Adjust a voltage just low enough so that saturation does not take place.
Divide the voltage by the amount of turns to get the volts/turn ratio.
Divide 220/110 by the v/t ratio and get the number of turns you need.
I am not perfectly sure, but I would say, that the total number of needed
turns divides up onto the two coils that are connected together ( 180° apart ).
Maybe another number of turns might even be better, but I would not go
below the numbers you derive from the process described above
Note that the presence of the egg might influence the inductance.

> The museum egg has around 82 turns per coil of what appears to be 12
> AWG cotton covered wire.
I wound a variac some time ago on a similar sized core and ended up with
170 turns for 220V service, so 82 turns seems to be in the right order.

> Any thoughts or comments on this would be appreciated.
you read it...
you can not unread it ;-)
Hope this helped a little, great project by the way and very nice workmanship,
maybe I will find the chance to build my own some time in the future.

best regards
Christoph Bohr