Thanks Lad,

I say that as it appears your about 4 years younger than me.

I knew someone would have sussed this all out as these things have been around for ages.

It appears I have a BCD version which transmits the seven packets of 4 bits.

I had already sussed out the odd bias that earths the +1.5V butten cell to the metal parts and that the clock and data lines go negative from this reference.

The links you provide will save me loads of time particularly the different protocols.

I'm surprised no one is knocking out cheap displays and cables for these caliper scales? What has happened to your prototype? Has it stayed in that breadboard form or have you advanced its build state? I would be interested to know what processor/controller you used for the decode/display driver.

I'm not too fussed about a connector to the gold contacts if they are not readily available as I would have just soldered wires onto the board. its not worth messing around for a £9 scale is it.

Have you managed to successfully transfer the scale head of these things onto a longer bar for machine mounting? I'm not clear how accurate one needs to emulate the original caliper slide bar as far as materials and texture need to be. Your comments on this mechanical aspect would be appreciated.

I will look at my other caliper recently purchased to see what remote display protocol it uses.

Thanks for you help so its been so refreshing to get expert advice for once.

Cheers,

John