Hi, Tony Duell said: I built things like that too, back in the late '50s/early 60s. It was a result of acquiring a box full of ex-WD neons for a few pence. Flip-flops worked nicely, but an attempt to build a decade counter came to nothing. We tried the effect of light on them too, some oscillators wouldn't work in the dark, and I remember a magazine article that suggested using neons as cosmic ray detectors. -- Cheers, Stan Barr stanb at dial.pipex.com The future was never like this!