gauge backlighting

Go LED. Much brighter, cooler and last about forever. I got tired of the burned out button lighting on the radio in my truck and after tearing it apart, I replaced the burned out incandescents with white LEDs.

Do they dim down OK or just drop out? I've got the same unit and was thinking about red LEDs. Then maybe doing the dash over the same way.

Has anyone found LED "bulbs" that work with indirect gauge lighting? I tried some on the Porsche and they were dimmer than the stock incandescents.

In fact, I've been pretty disappointed in all the LED products I've tried; I bought some LED 1157 bulb "replacement" and they were hopelessly dim from straight on and worse from an angle

nate

They dim, but not much. they pretty much stay at full brightness more or less all the time. I have LED's on the Porsche (not the bulb replacements, a full kit replacing the bulbs, "light guides" everything) and they are fantastic in terms of actually being able to *see* the gauges, but dimming is not so good.

nate

I wondered about that as well, but since I never change the dimming level I figured it wouldn't matter anyway. As it turns out, they track the brightness of the rest of the dash incandescents pretty well.

Those are the Digi-Key P/N 160-1734-5-ND White T1 1100MCD LEDs running at about half their rated current with 1K ohm resistors P/N 1.0KEBK-ND.

You might have some issues if you went with a color like red. The buttons and other display areas already have greenish color filters on them since they were designed for the white/amber incandescents. With the white LEDs which lean towards bluish, the radio buttons ended up somewhat blue as you can see in the pictures, which works fine. With red LEDs I'm not sure the results would be pleasing. Easy enough to experiment though.

No problem at all on the radio buttons, indeed they are quite bright and I'm running them at about half their rated current.

If you have a situation where the light guides are relying on side output from and incandescent, I'd use surface mount chip LEDs and arrange three of them standing up in a cluster facing outward to get the correct light distribution.

If you're replacing larger bulbs like the 194s then just use the T1 LEDs arranged the same way. All the LED specs are on the Digi-Key site, as well as those for most incandescents, so it's pretty easy to compare the MCD ratings.

Not the ones I used. I thought that might be an issue, but it turns out that they track the brightness of the rest of the incandescent dash lighting just fine. The LEDs I used are rated 1100MCD at 20mA, and I'm running them at about half power.

Sounds like those LED kits weren't designed very well.

Good to know they will dim. I usually cut the dash lights down a good bit at night. I noticed the 1K dropping resistors. Looks like some more things to play with...

That's exactly what I did; I was using 194-format bulbs in the dash of the Porsche and bought some that sound like you describe I think from superbrightleds.com - they *were* red FWIW but the light output was very disappointing.

for my current issue I found some 1816s at my FLAPS on my lunch hour, I'll try those in place of the unlabeled bulbs in the Sunpro gauges (they appear to be 53s or something similar) and see if they provide acceptable lighting after dark.

nate

Followup: the 1816s did improve the lighting, but the design of the Sunpro gauges is simply inferior to the VDO. Now I think the bulbs are roughly comparable (the 1816 draws 4.29W while the 158 used in the VDO gauges draws 3.36W; the bulbs originally in the Sunpro gauges were unmarked but look like a 53 and were pretty dim) but the VDO gauge has an extra reflector behind the bezel to deflect more light onto the face of the gauge, while the Sunpro gauges do not - so when you look at them at an angle (say, when they're mounted in an under dash gauge panel) you see a bright crescent of light at the edge of the gauge but the face still isn't as well illuminated. Plus the 1816 is simply the brightest bulb I could find in that format; the 158 in the VDO gauges could easily be replaced with, say, a 194 or W5W if I needed to make it brighter relative to the dash panel so that I could dim the dash panel to a comfortable level and still have the auxiliary gauges legible.

Lesson learned; next time I'll spend the extra $10-20 a gauge to get the VDO. I figured "hey, it's just an old work truck, cheap gauges will be fine" but sometimes nice stuff really is worth it.

nate