Battery charger

Some time ago, I bought a 1940's style battery charger at a Wessex SEC crank
up. The intention is to run it off an appropriate stationary engine & dynamo
(110 volt) It is very pretty and looks far older than its years, the style
being early thirties.
I gave it an initial clean up and check over, noticing that the rectifier
valve was missing, but otherwise it was very complete & certainly worth
further investigation. On the front was a little badge that said "Ray
Engineering, Bristol." Now, I knew where they were as I did my time in
engineering at a small factory just up the road from them. Passing by, I saw
they were still there and returned with the battery charger in the hope of
finding a circuit diagram. After an initial "we make plastic knobs, not
battery chargers", someone a good deal older was found who knew that they
had done so long ago & I was ushered into the foyer to await developments.
There on the wall was another, identical except for the pristine paint,
polished brass and tag saying "Battery charger, Circa 1952")
The MD appeared, enthused, said decisively that all the paperwork had long
since been chucked away - but they did have a box of left over bits from the
restoration of the one on display, So over I go again this morning to
collect same. A useful lot, including a valve, some terminal knobs and a
switch that I needed.
Still no circuit diagram though. Is there perhaps a generic source for such
things ? I know you can get books of circuit diagrams for old TV/s.
Regards,
Kim Siddorn