Lotus Elan

Instrument Illumination

PostPost by: bcmc33 » Sat May 26, 2012 11:58 am

elansprint wrote:Brian looking at the LEDs fitted into std lamp configuration they have LEDs mounted around the edge as well as facing forward this should help as LEDs tend to have narrow veiwing angles in comparison to incandescent lamps
Ian

That's exactly what I said was required after I bought the useless forward facing ones.

I'm sure I was not the first person to tell them that these bulbs needed side facing illumination.
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PostPost by: simonknee » Sat May 26, 2012 3:50 pm

If anybody has (or does) tried the stop/brake light units from these guys then please let us know how they are. I am pretty paranoid about people not seeing the standard incandescent ones on my S3 these days and would love something super bright to startle tailgaters.
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PostPost by: Galwaylotus » Sat May 26, 2012 5:06 pm

Not sure about the UK but you want to check that whatever lights you install aren't too bright to pass the MOT test.
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PostPost by: holywood3645 » Sat May 26, 2012 6:00 pm

On my S4, Its the Speedo and Tacho have the issue. The oil/water and fuel are fine (better) Is this the same on the other series of elans?
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PostPost by: Frank Howard » Sat May 26, 2012 6:16 pm

James,

It's because the Speedo and Tach use the same puny 2.2 watt lamps as the small gauges. Because they're larger, they're even dimmer.
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PostPost by: Galwaylotus » Sat May 26, 2012 8:59 pm

UAB807F wrote:
Galwaylotus wrote:Make sure to get "superbright" LEDs and you need an in-line (series) resistor sized to the LED characteristics. I've done all indicators for my Mini as well as the illumination for the speedometer. I probably should have gone for a brighter LED for the illumination but it is readable and whiter than the normal bulbs. For my low oil pressure idiot light I bought a 10 mm flashing red LED which works well. The flashing LEDs have built in circuitry which obviates the need for a separate resistor. Good luck.


Hi there,

Any chance of posting a diagram and/or shopping list for us non-electrical numpties ? (being selfish it would be even better if it was a Maplin shopping list :wink: ) I'm quite happy soldering things together but know nothing about working out a circuit for LEDs and I quite like the idea of lower power consumption & presumably less heat generation.

Brian

Brian,

The bad news is that I did this a few years ago and cannot find my notes; however, the good news is that the LEDs came from Maplin and they just need a resistor in series to operate correctly. I think the Maplin catalog has some information on the proper resistance for each LED. I built a fibreglass instrument panel for my Mini and used LEDs for the relevant lights (directional indicators, main beam indicator, etc.) and to illuminate the speedo. The latter wasn't as successful for the reasons mentioned on this forum but If I tried a bit harder I probably could have resolved that one too.
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PostPost by: simonknee » Sat May 26, 2012 10:32 pm

Galwaylotus wrote:too bright to pass the MOT test.


Have you seen the Christmas display festooned across the rear of most modern vehicles these days!! :D
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PostPost by: Frank Howard » Sat May 26, 2012 10:42 pm

I started this thread with a straightforward, easy inexpensive fix to the instrument illumination problem. Call me old fashioned, but why do some people feel compelled to add on a complicated alternative solution that introduces a whole new set of problems?
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PostPost by: ricarbo » Sun May 27, 2012 8:27 pm

Using LED's is not difficult. They drop 1.2 volts and draw about 20 milliamps (0.02 amps). so the calculation is (for one LED)

supply voltage minus 1.2 (let's say 14.2 - 1.2 = 13).
then, using ohm's law

13/0.02=650 ohm resistor - use nearest standard value of 680.

two led's in series drop 2.4 volts, so
11.8/0.02 = 590 ohms - use nearest standard value of 610.

the important thing is not to put too much current through them. extra current blows them, but in practice they are just as bright with lower current, unless you go so low they completely fail to light. perhaps 4 milliamps. you can't adjust the brightness by changing the resistor.
in practice, it's ok to use a 1000 ohm resistor (1k) for 1 or 2 leds.

as they are 'narrow angle' light emission, you need to fiddle around to get the result you need, but once you've done it, they are extremely reliable and run cold, so don't damage the paint inside the gauges.
you may not like the whiteness of the light, compared to the original lamps.

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PostPost by: Sea Ranch » Sun May 27, 2012 8:38 pm

Excellent thread; glad the discussion has been renewed.

I'm wondering if part of the problem with the factory setup is the voltage regulation and lack of full voltage to the lights due to grounding or worn-out/improperly adjusted voltage regulator??

Just a thought . . .

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PostPost by: Frank Howard » Sun May 27, 2012 9:41 pm

ricarbo wrote:...they are extremely reliable and run cold, so don't damage the paint inside the gauges...

I had no idea that the incandescent lamps were damaging the paint inside the gauges. I'll have to check mine to see how much damage I've caused. :wink:
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PostPost by: UAB807F » Mon May 28, 2012 6:25 am

ricarbo wrote:...an excellent guide...
Richard


Richard, thank you for the info, it's all embarrassingly simple, logical and I really should have worked that out for myself. My only feeble excuse is that it's been a long time since my Physics O level. :oops: I wasn't thinking of instruments if I'm honest, I was wondering about the number plate lamps at the back.

Galwaylotus, thanks for the pointers as well. Maplins recently sent me a catalogue resembling the old telephone directory so again with some application I should make progress. (ironically, when Maplins send 4/5 page leaflets I tend to read the lot but with the magnum opus they sent last time I just put it in the shelf with the other references, never to be opened !)
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PostPost by: simonknee » Mon May 28, 2012 8:57 am

The "old fashioned" here are looking for http://www.cp-lighting.co.uk/10X28-12V-4W-330mA-MES

I found this by using the new-fangled google to search for "mes bulb 12V 4W". If that is not quite the right style it looks like cp-lighting will have something that suits (no I have not used them but they are now bookmarked). Since google displays local suppliers perhaps the same search in your neck of the woods will pull something up a bit nearer than Surrey!

MES = Miniature Edison Screw
See: http://en.wikipedia.org/wiki/Edison_screw#Types

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PostPost by: Higs » Mon May 28, 2012 10:42 am

And even 6 watt ones here......

http://www.autoelectricsupplies.co.uk/product/499/category/92

So we have enough bulb types to set up a side by side test for brightness, whiteness, paint degredation(ess) etc..

I look forward to the fullsome report!

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PostPost by: Frank Howard » Mon May 28, 2012 2:41 pm

Simon & Richard,

Good find! And as I said in my initial post, if you install the 4w bulbs in the smaller gauges and the 6w bulbs in the larger ones, the brightness will be close to the same for all 4 gauges. More importantly, all 4 gauges will be legible at night :!: I know this first hand because I have yet to convert the bulbs in my Europa. There is a significant difference as I can read one set at night but not the other.
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