SINCLAIR BLACK LED 1976
If you have ever heard of the ZX Spectrum, one of the first personal computers from the 1980's, then you will appreciate that the Sinclair company was into electronics much much earlier. Sir Clive was a quirky inventor and entrepreneur manufacturing radios, calculators, TV's and remote controls and he had definitely more technical brains than economic flair. Except the ZX Spectrum quite a few of his inventions proved to be a complete bust and the Black LED watch was one that almost bankrupted the entire company. Developed solely inhouse it was marketed during the golden age of digital watches in 1975-76 as a self-assembly kit for the hobbyist at 17.95 or a complete watch with box for 24.95 pounds. Sadly many malfunctioned and were returned for repairs and the Sinclair company had to be rescued by the British government.
The watch was cheaply made from light-weight ABS plastics providing absolutely no water resistance and being quite flexible when operated. This flexibility was intended as the command buttons/pads were on the top of the case flexing just a few microns whenever pressed with a finger. On the inside of the case the button locations were fitted with thin foam pads covered with aluminium foil which, when pressed, shorted the traces on the module thus activating a display read-out: 2 pads on the front and 1 on the back for setting. Many modules died of rapid battery exhaustion when the button pads remained in their shorting positions, mainly due to the module not perfectly secured in the case as it was only bolted in the case with 4 metal pins but the case still flexed under pressure when depressed.
Further issues were caused by the battery clamp being held in place with only a plastic divider and the batteries also moved a bit in the case increasing the risk of short-circuiting. The final success of the watch was heavily dependant on the qualifications of young hobbyists assembling poor quality parts at home so this shouldn't be a surprise that the repair backlog at Sinclair HQ reached 2 years at one time. Several upgrades were made as technology progressed and modules fitted with 4 or 5-digit displays (date and/or seconds). As pictured, some early versions were completely sealed in a copper foil cage with large IC packets by ITT Semiconductors (dated week 10/76) while other had small integrated Intel microchips (dated week 08/76) hidden under a piece of grey plastic serving as a platform for the touch pads.
The user manual on some versions explained that the two touch buttons/pads (showing time or date on many models) were used to get a normal or increased brightness on the display but to me they both displayed the same. Most if not all suriving Sinclair Black Watches will be non-operational with battery leakage and damage to the battery terminals printed on flexible foil. You are likely to be lucky if you clean the leakage and rewire the terminals but chances are below 50%. Black plastic was used for most watches and sold with leatherette straps or black-coated stainless steel bracelets. Some limited editions were sold in grey or white plastic and are very hard to find.
Keywords: sinclair led, black led watch
Market value: 100-300$ (condition, factory built or kit, box)