I know that Caerbont Automotive Instruments (Smiths) have had a lot of trouble with the colour of the light from LEDs for their new range of small instruments. The oil, fuel, and temperature gauges that they made for me use 4 small LEDs on the circuit boards. These LEDs (in their uncoated state) render an almost blue light and to reduce the light to a colour temperature near to the incandescent bulbs they have coated the LEDs with a special paint.

Unfortunately the end colour is not exactly the same as the incandescent bulbs which by comparison render a light which is slightly pink.

In order to resolve this oddity I have now purchased quite a few different types of LEDs. The cost is not great but the time involved is becoming quite significant. I have now found a supplier who has LEDs which have a good colour temperature, somewhat cooler than incandescent but not far from the LEDs (coated) that Caerbont have used in the small instruments. I am still experimenting a little as to the number of LEDs which would be suitable. 4 LEDs seem too bright and my next attempt will be with 2 LEDs.

The main problem is that two different size bulb sockets are used. The original 3 in 1 instrument and the clock (if fitted) use what is known as T10 size in a push in holder and the speedo and tacho use the smaller T5 size in a twist lock holder which is hidden under a rubber cover.

So far I am modifying a small circuit with 8 LEDs to experiment but when I am satisfied with the result I will ask the supplier if they can make both T5 and T10 with the specified number of LEDs and what the minimum order quantity would be.

I will keep you posted if I am able to get a satisfactory result. If it works out I will see if I can put together a kit with fitting instructions.

PS. Dave. Going back through your photos I see that the earlier Caerbont small guages used in the Roadster use the T10 bulbs and do not have the LEDs internally mounted that my small instruments have.

Last edited by Gambalunga; 30/08/17 07:33 AM. Reason: PS
Peter

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