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  Using LEDs in Instruments

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  LED in Dash tests

David conducted some tests looking at the practicality of exchanging incandescent bulbs in the instrument fascia with LEDs.  These tests are a rough guide only, to show what a dash might look like using LEDís, and these are his results.

The test dash is from a 1990 Granada and photographed in a semi dark room.

I used small wedge type white LEDís (286) as they were cheaper. They are very directional compared to a normal bulb. I got them to fit in the larger holders for the tests. This would not be practical for normal use. You would need to use 501 size wedge bulbs.( but not the equal to 5w ones )

 Photo 1 Ė normal bulbs x3 positioned behind 20, 80, 140. The wide angle of light dispersal illuminates the rest of the dial.

 Photo 2 Ė One LED positioned behind 80. Two normal bulbs behind 20 and 140. Here you can clearly see the blue tinge that is a minor problem with white LEDís. Also because of the LEDís being directional there is loss of illumination at 40-50 and 100.








 Photo 3 Ė Two LEDís one normal bulb.

Photo 4 Ė Three LEDís here you can clearly see the lack of illumination at 40 and 100 / 110. However to the naked eye I think it is still visible enough.









Photo 5 Ė One normal bulb, slightly over exposed.

Photo 6 Ė One LED, this time the light fall off is noticeable on the temp and petrol symbols. The pointers look fine.


Photo 7 Ė Two normal bulbs , slightly over exposed. 

Photo 8 Ė Two LEDís seem to get good illumination over all. 










 Photo 9 Ė Normal bulb in rev counter and normal bulb in battery charge light. I deliberately left this over exposed. First reason all photoís have the same settings. Secondly to show how bright a normal lamp is when concentrated in a small enclosure.

 Photo 10 Ė Normal bulb in rev counter and LED in battery charge light.



These LEDís were more directional than a normal bulb.

They were polarity sensitive i.e. if you put them in the wrong way round they will not work.

You could not use them with dimming circuits like on the Granadaís


I think the LEDís will be good enough if the correct size is used and they are advertised as wide angle. The latest LEDís are brighter still.

The 501 (large ones) size holders are easy to change the wedge bulbs for LED wedges

Donít buy the multiply LED 501ís as these are for side lights.

The smaller wedge bulbs will be difficult to change and Iíd suggest buying the holder as well.

 These site examples are where I bought the LEDís from. I have not looked else where for price comparisons or different makes (probably all from China anyway)

So in the end if they are good enough for you they should outlast the life of  the vehicle and not require taking the dash apart every 2-3 years J to replace blown bulbs

 One final thought that occurred to me whilst reading some posts on the email list about checks when starting a car after its been standing. battery, oil, petrol etc. How many of you check your warning lights are working when starting the car every day / week?

Thanks to David for the text and photos



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