Do the secondaries need to be isolated from each other? If not then a
10-0-10 would be close enough to 9V and in series give 20V. I'm not sure
if there are many transformers with this output. 9-0-9 used to be more
common.

Yes they do one drives the motors at AC as best I can tell, the other 9
volt supply the microprocessor and display..


Maybe the cheapest auto-transformer is a standard one with 2 x 110V
primaries. I expect a true autotransformer with the same rating will be
smaller.


Thats what is in use at this moment. Pending the compact 230 volt step-
down..

If you opt for 2 transformers remember they don't have to be so large.
The rotator power is also likely to be intermittent and that can be
reflected in the transformer rating.

Indeed..
--
Tony Sayer


Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.