Can't see them listed at the moment but a short while ago I got two of these Unilab Counter Modules off eBay. They must be classroom demo stuff that's now been superseded. I bought them to include in a pendulum clock I'm building. I have managed to change the count to 15 but I'm working blind and need to know more about the circuit.
Can't find anything on the internet. So I'm wondering if anyone here has a circuit diagram or knows where I might get one...

 

Shouldn't be very difficult to trace it and make your own schematic. Why did you need to change it to count to 15? It's a binary counter.

EDIT: Googled and found that it's still being sold. http://www.philipharris.co.uk/product/MFA-Counter-Module-B8H28079
You might try contacting them to see if you can get a schematic.

 

Yes, it is the top board in that advertisement..But the ebay seller I bought from had several quite recently and the BIK price was £4.50 !
I needed to change it to /15 because it's part of a clock I'm building. It will need to be fed from a /2 (4013) and will count seconds to drive a clock dial that needs an impulse every 30 seconds.
Circuit tracing would be a problem for me (analogue bloke really) and there's a chip on it (cd4019) that I just can't get my head around.
Although since my original post I think I know why it's there and one problem has been overcome.
I will try emailing the seller you linked to - good suggestion.
A blog about the clock construction is current at www.rogerj.co.uk/clock.htm is anyone is interested in such things