Make:

• Learn about electronics: Relays 101
• How-to Tuesday: USB7 build
• SV Chronometer – a GPS based, interactive master clock
• Record your heatbeat for the neighborhood to see
• Desulfator kit
• Using a DC motor as a servo with PID control

Posted by: Doctroid on July 8, 2008 at 5:19 AM

Sorry, but the description is all wrong. It's not a watch, it's a calculator; it's not modelled on the ZX-81; and it's not an homage to Sinclair, it IS a Sinclair, vintage 1977. Google for 'Sinclair wrist calculator' for info.

Posted by: anachrocomputer on July 8, 2008 at 6:55 AM

The above comment is correct. It's the Science of Cambridge wrist-calculator, sold commercially as a kit in England in the late 1970s. I wish I'd bought one! Science of Cambridge was one of Sir Clive Sinclair's companies, somewhere between Sinclair Radionics and Sinclair Computers. The Sinclair wristwatch was called the "Black Watch" and was notorious for trouble with static affecting the chip (it had a black plastic case and no shielding). I saw one once, in 1979 or so, and again, wish I'd bought one!

Posted by: anachrocomputer on July 8, 2008 at 8:25 AM

Bah! Now I've got my information wrong! The company that built the Sinclair computers was Sinclair Research. I just checked the back of one of my Spectrum manuals, so that should be correct.

I had one of those! Might even still have it if I dig deep enough. It was sold as a kit, and as the other comments noted, it's a calculator, not a watch, and it pre-dated the Sinclair computers by years.

When I got it, I thought it was the coolest thing ever, but by the time I had assembled it, my opinion had changed for the worse. It was mechanically terribly flimsy, and it was powered by a stack of button cells that ran right along that bulge at the top, just behind the display. As you can probably imagine, that stack of batteries was very flaky, and any jolt or vibration would reset the thing.

I think I only ever used it a couple of times. 8-(

Posted by: anachrocomputer on July 8, 2008 at 5:11 PM

Hiro, I hope you find it! I was up in the loft just now, and I found an old Practical Wireless (Nov 1977) with an advert for the more advanced version of this calculator. Well, I couldn't resist scanning it:

http://www.gifford.co.uk/~coredump/sinclair_wrist_calc.jpg

I probably still have the PCB & display somewhere, but I think the case & strap are long gone.

Thanks for posting that ad, it was probably the one I replied to, as I used to read PW in those days.

Posted by: csf0137 on July 9, 2008 at 9:07 AM

it's look like this:

http://www.calcwatch.com/index.html

I just bought one %-)

Posted by: csf0137 on July 9, 2008 at 9:17 AM

http://watchismo.blogspot.com/2007/11/vintage-watching-1970-prototype-concept.html

Yes! Yes! I remember staying up late soldering together my Red LED Sinclair digital kit watch and powering it up!
I woke my brother up to show him how cool it was! That had to be somewhere around 1974? I remember that was the whole power trip of the LED watches, people couldn't see what time it was without asking you to activate it. And then you would proudly show them the time. I rememebr the seeing one of the first LED digital watches in a James Bond movie. Not sure which one that was though. Thanks for the flash-back!

-Todd

I had this back in 1979 or so. My version was more scientific (I don't know if Sinclair made more versions) but there was a slide switch across the bottom that wasn't that great. I fabbed a new one from Al, but then got too clever with the soldering iron. It's still in parts...but I have it and the manual. Gotta get it scanned!

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