Thanks Peter
Sounds a good piece of advice. I must admit I started off without thinking about opto isolators but have got a bit 'windy' - hence the question. I am debouncing the 'clock' inputs for the lap counter in software but these remote panel selectors are far less fussy, so I'll try the simple way first. Thanks for your advice. By the way we have an Australian visitor staying with us at present - he flew over to the UK to take part in some model team race flying National event we have here each August. He is from Parkville in the centre of Melbourne

Regards


Adrian