I had some success making a pointer device for a trust digitiser last
year. I didn't actually need one for that device, I was using it for
investigation.

The tablet I need a pointer for, because they're very expensive to buy,
is a Calcomp DB3. When I came to investigate this board, I couldn't
find the HF signal to feed the pointer as in the trust device.

Of course it's possible the calcomp doesn't work, I got it in an
auction with some other kit 10 years ago!

Anyone have any experience with these?

Cheers,
Alex