Hi Stuart,
No problem - input is 16v AC.
To convert it to DC I used one of these:
https://www.ebay.co.uk/itm/264940437804?hash=item3dafae412c:g:VDgAAOSwZzxgyVLF
then used an LM7812 voltage regulator to give a steady 12v output. The rectifier above has an output of 22v DC from a 16v AC input, so a bit high :).
The 12v DC output from the LM7812 then goes in to one of these:
https://www.ebay.co.uk/itm/193312727515
which controls the voltage to the track. It has an "off" position on the pot. which is handy.
The track output goes through a DPDT switch to reverse the polarity and give forward and reverse control.
I got the bits from AliExpress - with a bit of a wait - for a good bit less than Ebay sellers want for them. This was however well pre Br%xit so import charges may well be a factor now.
Hope this helps,
Les