What Brightness LED's for Guages?

[pete]

My tacho light no longer works and I'd also like to just go and replace all the bulbs in my instruments with LED's while it's all apart.

I've read up on Matchless' PDF to replace the bulbs with LED's and I've seen various threads on here related to this, however I haven't seen anyone mention the actual brightness of the LED's that're required.

I have four different brightness of white LED's available; 4000, 10000, 18000, and 40000MCD.

I'm guessing that the 40000 will be too bright and are better for things like running lights as Audi etc. has done.

So, anyone have any idea as to which ones I should be going for? They vary in price from $2.45 (4000MCD) each to $5.95 (40000MCD) each.

[bakalorz]

My tacho light no longer works and I'd also like to just go and replace all the bulbs in my instruments with LED's while it's all apart.

I've read up on Matchless' PDF to replace the bulbs with LED's and I've seen various threads on here related to this, however I haven't seen anyone mention the actual brightness of the LED's that're required.

I have four different brightness of white LED's available; 4000, 10000, 18000, and 40000MCD.

I'm guessing that the 40000 will be too bright and are better for things like running lights as Audi etc. has done.

So, anyone have any idea as to which ones I should be going for? They vary in price from $2.45 (4000MCD) each to $5.95 (40000MCD) each.

the mcd is the intensity within a certain angle.

A lot of times they will take LEDs with a certain amount of light and just focus it tighter to get higher mcd numbers (but only within a narrow beam ... say 10 to 15 degrees).

for gauges I would guess you want a fairly wide beam, at least 30 or 40 deg or more ... so check the beam width too.

My guess is that the high mcd LEDs are too narrow.

I would guess that other than that you want the brightest LEDS possible.
You can always easily reduce it by providing less current (i.e. a bigger resistor)

[BassCliff]

Hi,

Well that's a very good question and it may take some experimentation on your part. For example, because the indicator lights are behind colored lenses, they may take a brighter LED than those used to illuminate the gauge faces. I'm sure others will be interested in your finished project. Please keep us informed.


Thank you for your indulgence,

BassCliff

[pete]

Cheers for the replies guys.

the mcd is the intensity within a certain angle.

A lot of times they will take LEDs with a certain amount of light and just focus it tighter to get higher mcd numbers (but only within a narrow beam ... say 10 to 15 degrees).

for gauges I would guess you want a fairly wide beam, at least 30 or 40 deg or more ... so check the beam width too.

My guess is that the high mcd LEDs are too narrow.

I would guess that other than that you want the brightest LEDS possible.
You can always easily reduce it by providing less current (i.e. a bigger resistor)

Cool, while I knew it was a measure of intensity, I didn't realise it was at a certain angle, that's good to know.

Reducing with a higher resistor makes perfect sense (bit of a der moment there for me), and my concern with the 40000 is that they'll be far too bright in my face.

The other thing with beam width is that Matchless has successfully ground the dome a touch to flatten it out, although that may reduce the intensity somewhat too.

Hi,

Well that's a very good question and it may take some experimentation on your part. For example, because the indicator lights are behind colored lenses, they may take a brighter LED than those used to illuminate the gauge faces. I'm sure others will be interested in your finished project. Please keep us informed.


Thank you for your indulgence,

BassCliff

It certainly will BassCliff, although I was hoping to short circuit (pun fully intended) the experimentation bit if someone else already knew

I may get somewhere today to pick one up of each and see how they look.

Cliff brings out a very good point. Different colors have better transmission through certain color lenses.

You may do well to match colors to the lenses, if the cost isn't out of line. If not, get brighter ones knowing it will be cut by the lenses.

I'm eager to see your results.

- John

Matchless successfully used white ones in his guide behind the coloured lenses and I wanted to stick with white if I could.

There's also a discount for buying 10+ where I get them from as well which makes that option a bit more attractive.

So seeing as it looks like there's interest in this, I'll definitely keep this updated with progress, and I'll be using Matchless' guide found here:

http://members.dslextreme.com/users/storagecliff1/images/Gauge_LED_conversion.pdf

This is of course hosted on the awesome BassCliff's site for all to peruse

[pete]

One thing I neglected to mention is that this is just for the guages, I'll be trying to source "appropriate" looking LED indicators and tail/brake light to suit the style I'm trying for, so I won't be putting LED's in them myself.

Over here, lights need to be government approved otherwise it'll fail the safety certificate and I won't be able to register it.

[Steve]

If you look at places like superbrightleds.com and suplerlumination.com, you will find LED replacement bulbs that are already set up for use in instruments. No need to specify the brightness, viewing angle, any of that stuff, just get the color you want.

.

[pete]

If you look at places like superbrightleds.com and suplerlumination.com, you will find LED replacement bulbs that are already set up for use in instruments. No need to specify the brightness, viewing angle, any of that stuff, just get the color you want.

.

Very true Steve, although for us suckers here in Aus, the price of things like that becomes expensive (apparently we believe in selling far fewer quantities for a much inflated profit than selling higher quantities to make them more affordable), and if you add postage to the ones from the US, it still gets a bit expensive, which is why I'm looking at doing the conversion myself as Matchless has shown.

On another note, I found the spec's of the LED's I'm looking at and the 4000MCD viewable range is 30 degrees whereas the others are 20 degrees which may be ok.

Anyway, I'll try to pick up one of each today if I can and see how they look.

[pete]

I picked the LED's up today, although what is on the shelf in store is different to their website...

Ended up with 1500, 8000, and 20000 I believe.

I also realised I have my old laptop power supply in the garage which I'm not using any more as the HDD carked it. It's 20v DC at about 2 amps, so will make a good power source for testing without jumping off the car battery all the time.

[pete]

I did a little with this tonight finally, but I'm posting all the details in my rebuild thread to try to keep things together... linkage in my signature below if anyone's keen to follow.

[Indysteve]

Hey Pete,

I just ran across your thread on the LED's and thought I would throw my 2 cents in

I was searching ebay the other day trying to scare up some of the old suppliers I used to get LED's for my HO trains.
I found a Chinese supplier selling 12V 10000 MCD bright whites for a reasonable rate.

A couple things to keep in mind, they sell an LED that does a more incandescent look if you want to mimic the original bulb.
If you tie all the grounds together you can use a single resistor on the ground leg to save money if you are using a lower voltage LED, although resistors are fairly cheap.

I tested a 10000 MCD with a 30 degree rate and found it to be a really close match to original.

Hope that gives you some help!

[pete]

Cheers Steve, all that makes sense for sure.

My quick testing showed me I wasn't quite happy with 8000, so 10000 or 13000 will be the go, and the viewing angle is definitely critical.

I'm just going to peek around eBay and see what's best. Some are being sold with free resistors also.

I notice they also have some flat top ones with 120 degree viewing angle, but I've only seen them in 1000 quantities so far which is far too many.

[pete]

I ended up ordering 20000mcd flat top LED's off eBay, dirt cheap in a bag of 100. Also ordered 100 470 ohm resistors to go with them.

Viewing angle should be 120 degrees so they should in theory go well.

Apparently I'll have them in 10 to 21 days...

[pete]

Same old story, Fast OR Cheap.

Can't wait to see your results!

- JC

So true! The price difference is obscene though, $US4.50 for 100 LED's and 100 resistors, meaning for me it was about $AU4.00 and in fact the postage was dearer.

If they had them locally I'd be paying something like $1 - $2 each for the LED's by themselves.

I can't wait to see the results either actually

[pete]

Ok, got the LED's and resistors today, so made a start.



So, just replaced the 6th gear bulb first, and compared with the 4th gear still as a standard bulb:



The LED looks a little dodgy in that photo, but it looked good enough in person to keep going.

So old bulbs out:



This was my first LED in for 6th gear which is what I used for the first test pic above:



And then I got all six done:



To get the LED lead length right, I just held them up against one of the bulbs and clipped them at the same length. While playing around I noticed if you held them too close to the number cutout, it would clearly show the outline of the LED and really cut the light output, whereas if you dropped it back to the same height the bulb sits, it made it much brighter and not so obviously a LED in there.

The viewing angle on these flat tops is great too, much better than a standard domed LED. Listed as 120 degrees and they're probably right.

So next I needed to wire in a 470 ohm resistor, which I did by desoldering the orange power lead and soldering the resistor in where it joined the circuit board, then soldering the orange power lead to the resistor.



Given the backing plate underneath clamps all the leads in place, there shouldn't be any vibration issues there either.

And got it all back together:



And here's a crappy little video of it working, and you can see that they appear quite bright. Real test will be daylight of course. The unsteadiness and wavering is me holding the negative lead from my power supply on each pin in the plug:



Next time I'll get onto the gauge lights themselves, but I think I'll end up with two LED's to replace each bulb, have to see how they look first.

Also, I realise Matchless' PDF guide has everything I'm doing covered off and what I'm doing here is essentially duplicating his guide, but this way it gives me a little entertainment also...

[Matchless]

I found my gear indicator with one LED perfect for daylight and night riding. With the bulb I could not see some of the numbers in sharp daylight.
You will be very happy with those! They look perfect in the video.