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Discussion Starter · #1 ·
Brighter Instrument Lights – My Solution

If you are like me, the dim instrument lights on your early Alfa (I have a 1969 1750 Veloce Spider) are frustrating. Mine were barely readable during night driving. I began to look for a solution.
If you’re willing to disassemble the gauges, you can make large improvements. Be sure to clean the glass while apart, and be careful about fingerprints.
After numerous weekends of experimenting, below is what I found:

1. 20 watt halogen bulbs:
These were great. They just plug in to the existing sockets. (You have to file down one of the bayonet tabs to get them to fit into the stock bulb sockets.) The effect was dazzling at night. However, this much wattage in these gauges makes them nearly too hot to touch. The speedo needle even developed a flicker. Fearing mechanical damage to the gauges from the heat, as well as fading the painted face numerals, I abandoned this idea.

2. Fiber Optics:
I wanted to try a flexible light “pipe” of about 9 mm diameter that could be inserted into the bulb openings. Then I could connect it to a very bright (and hot) external light source, like the 20 watt halos. The ones sold by Bivar: http://www.bivar.com/ looked great, but I couldn’t find them in smaller than quantities of 100.
I experimented with bundles of the cheap type of optical fiber you can get on those “novelty” lamps that look like some kind of sea anemone ( a hemispherical spray of fibers that are lit on the tips). They just didn’t transmit enough light.

3. Computer case glow pipes and tapes:
These are the small, flat tapes of glowing neon (some are called neon pipes) that some of the computer gamers use to decorate their cases. They are very thin, and can be wrapped around the inside of the gauge case/can right below the face. They also just didn’t provide enough light.

4. LEDs:
This is the one that works, and very well. All the LEDs I experimented with were from : http://www.superbrightleds.com/1157.htm and are for 12 volt automotive application – intended for drop-in replacement of existing automotive bulbs.
I tried seven different types as shown in the images. You can see them on the above website better than here :
They were :
1156/57 these have 12 forward facing LEDs These were too big to fit.
7443 – have 9 forward + 6 radial LEDs (undocumented feature, two brightness levels) and must mounted in large gauges sideways (images).
WLED – built in diffuser to spread light in all directions These were too dim.
WLED-W4 - have 4 forward facing LEDs – will mount in small gauge bulb openings.
921-W9 - have 9 forward facing LEDs Too big for small gauges, too dim for large ones
4410 Festoon - cylindrical with 9 upward facing LEDs Too big for small gauges – give too uneven a light pattern in large gauges.

The final configuration that worked best is :
Large gauges: two 7443s in each gauge. 125 mA draw each. Mounted on their side with wire ties through 2 small holes I drilled in the case. (see images)
Small gauges: one WLED-W4 ( 20 mA draw each) in the original bulb socket with a home-made holder out of 15/32 in. brass tubing. ( see images)

Total current draw is : 560 mA or only about 6.7 watts at 12 Volts !!

Caution: the 7443’s have two brightness levels – an undocumented feature. Connect 12V across the two outer contacts for brightest level (there are four contacts in all). You get the dimmer level by connecting across one inner and one of the outer contacts on the unit’s other side. This will be clear as soon as you see this LED.

Results are great, as shown in the images. (coming up)


General notes:
- I had the convenience of having a spare set of gauges from a parts car to do all the “practice” on.

- All these are white LEDs. You may like one of the other colors available. I also tried amber, but didn’t like the effect.

I got the idea of how to open the instrument cases from Willie R.’s excellent website:
http://www.veloce.nu/. I opened a total of ten instruments ( my spare set + the car’s) without breaking any glass, but be careful as Willie points out.

The first case I opened mystified me as to why it was blue inside. I finally realized it was to preferentially reflect the blue end of the light spectrum coming from the bulb’s yellowish light to get a whiter color onto the gauge face. Unfortunately, this means that much of the light from an already dim bulb is absorbed, not reflected, giving even dimmer, albeit white, light.

THE BIGGEST SINGLE (AND CHEAP) IMPROVEMENT YOU CAN MAKE IS TO MAKE THE INSIDE OF THE GAUGE CASES REFLECTIVE. Just how much difference this makes can be seen in the images. I foil-lined them as well as the backs of the dial faces and retainer plates, as shown in the images following.
This greatly improves reflectivity. Be sure not to miss the back, sides, and edges of the retainer plate (small gauges) and retainer ring (large gauges). This is the piece just below the glass, (not the dial face with the numerals on it). All surfaces which “see” light need to be treated. The edge of the retainer plate/ring is stepped in appearance and is where much of the reflected light turns the corner onto the outer face of the gauge.
The foil I used is actually foil tape with an adhesive back from Home Depot and is intended for HVAC use, but any highly reflective coating will work. I considered painting the insides with chrome paint, but decide against since this is irreversible.

The low-light images are valid comparisons of relative brightness. To make them, I set the digital camera on manual mode and used the same exposure (f2.8, 1.3 sec) for all images. There is a huge range of brightness from the original stock configuration to the others – its for real, and not exaggerated by the camera.

I ran the ground wires from each LED to a new ground “rail” wire which was firmly connected to a clean ground screw on the body. This gets around the issue of relying on the multiple contact ground path in the original bulb design (through the instrument case to the mounting bracket, etc.), which is prone to corrosion and electrical resistance.

The small gauges use a single WLED-W4 (white) each. These are mounted in 15/32 in. thin-walled brass tubing I got at Ace Hardware. This tubing slips perfectly into the existing bulb socket. The WLED-W4 also slips perfectly into the tubing. A fortunate pair of circumstances ! A drop of hot glue will hold the WLED-W4 in place in the tubing. No glue is necessary to hold the tubing in the instrument case socket. I also inserted a rubber wire grommet into the end and sealed the opening with hot glue.
Warning !! : do not insert the tubing/LED assembly too far into the socket. If you do, you will crush the foil cone you have fabricated on the back of the dial face. (images) It is there to disperse the “straight-on” pattern of the WLED-W4, which is aimed right into this cone. Rather, mark the maximum depth of insertion before you assemble the gauge with a marker on the outside of the brass tubing. See the images for an explanation.

Well, I’ll stop here for now. Hope this may be of some use for others who want brighter instrument lights, or at least provide ideas that can be improved on.

Cheers
 

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Discussion Starter · #3 ·
Cont.-Brighter Instrument Lights – My Solution

Had to cut this one down to post it. Its supposed to be the fifth on in the sequence.
 

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Dash Lighting

Thanks for sharing the interesting write up. It looks like a lot of work, but it sure would be nice to see my oil pressure and water temp gauges at night. R2
 

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What an awesome write up. Excellent work. I will add that one thing that I did that greatly improved my gauge lighting on my 78 was the addition of a late model higher amp alternator. But even with that, the gauges don't look near as good as these.

Best Regards,
John M
 

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I'm curious, how do LEDs react to the dimmer knob? (I don't have a dimmer knob in my '71; like I said, I'm curious.)

I'm someone that's always turning down the instrument lights in other cars. With the Alfa I wanted more light, but I found that cleaning the contacts and connectors brought the illumination up an appreciable degree, to the point that I like the large gauges where they are. It's nice, though, to have options, and adding the foil is very tempting. Excellent write-up and clear photos. Thanks!
 

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Great tip! I definately need better instrument lighting at night with my eyes. I don't understand the foil bit though. I understand lining the case with reflective foil, but what about the back of the dial face (6th picture on right). How does the light get through to the front of the dial face if the back of the dial is covered with foil?

John
 

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How does the light get through to the front of the dial face if the back of the dial is covered with foil?
It's not coming through the dial, but rather around the edges of the dial and illuminating the front from there. The foil reflects more and lets it come around to the front rather than be absorbed into the back.
 
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Thanks, That is what I thought it might be (iluminating around edge). I am going to just try the foil for now (cheap fix, the LED bulbs list for $6 ea). Any improvement would be a good thing. I need the same fix for my 99 Honda Valkyrie. **** these eyes! too late! (Young Frankenstine).

John Reinschmidt
76 Spider, Austin Tx
 

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Discussion Starter · #10 ·
Brighter Instrument lights reply

Thanks for the comments guys.

Farace, you are exactly right. The light is reflected around the edges of the faceplate. The idea is to keep as little light as possible from being absorbed by internal surfaces, and keep it "live" and bouncing around till it finds its way around the edges. Thats why the foil along makes such an improvement.

Someone asked about a dimmer. My car doesn't have one, so I can't say from personal experience. However, these LEDs are for automotive application and there is a whole group they sell just for instrument clusters and dashes. (The WLED series is one of them.) Since modern cars all have dimers, I guess I assume its O.K., but its a good question.

JJB
 

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Would it be possible to coat in the inner surface of the glass faces with a reflective tint to bounce the light more around the face of the dial? I am thinking that you could use a mirror tint (IE one way mirror) which would allow you to see the dial but may make the face brighter?

Kelly
 

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about the LED's and dimmers, because LED's are in fact Light Emitting Diodes, I expect there is some threshold voltage for them to conduct. this is normal for all diodes and probably around 3-5V for the white ones here. Before that voltage there will be no conduction, and after that voltage current will develop exponentially with respect to voltage. (like picture 1). so once they're lit, they're practically at full intensity right away. This makes them hard to dim , unless you have a very precise control of voltage right in the transitional area of the graph.


Fear not! if you add a resistor in series to the LED you can "stretch" the voltage current relationship out. While the relationship isn't perfectly linear (ie. a little more voltage gets you a little more current in a constant relationship for any value). it requires less precise control of voltage to see a varied response to current. (like picture 2). The resistor will decrease the efficiency of the circuit, but that the price you pay.

About the LED threshold voltage, if you have four LED's in series then you'll need four times the voltage to get them lit. It'd take some calculation, or fooling around, to figure what the threshold voltage of one of those bulbs is, if all the LEDs are in series or what. then you'd have to size your resistor so that the 0-12V coming from your dimmer translates to a voltage range that'll effect the LEDs. if They're working out of the box with a 12V supply, then chances are they they won't work at all with much less, dimming might be possible in a 11.5-12V range. Of course there might be a resistor already in the unit. which would also effect the range.

All in all I think it'd be possible, your dimmer probalby wouldn't work over its enitre range, and you may have to play with the circuit a bit to get things working.

Not straightforward perhaps, but possible for sure.
 

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The dimmer knob on my car only controls the accessory lights, not the instruments, so it should not affect the leds, unless there's something wrong with the wiring of my car.

Andre
 

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you can use the dimmer switch to control the LED's but you'll find the adjustment isnt linear like with a standard filliment bulb, although it does serve to reduce the brightness from blinding to tolerable :)
 

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Thanks, v. informative. Being an electrician for the last 22 yrs. I find that all v. interesting...but time consuming. I had the same condition w/ my 67GTJR. I contacted my local electrical supply house and ordered 6w bulbs. Both GE and westinghouse have a special order dept. and are glad to oblige.
 

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Thanks for all your work sharing this with the group. I just have all my gauges closed again after cleaning them, and I am afraid I do not want to open them back up again :eek:
What is the effect with the 6 watt bulbs? Are they the big ones, or also for the small gauges? No overheating or anything? I need to order new bulbs, and would love to go that route, if I knew exactly what to order :confused:
 

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with the help of Bob Farace I was able to locate this thread...

in here it mentions using "Large gauges: two 7443s in each gauge. 125 mA draw each. Mounted on their side with wire ties through 2 small holes I drilled in the case."

since he had to modify the cluster to install these bulbs, what is the stock bulb size? Im afraid to drill into the cluster, but would like to change my stock bulbs to red LEDs...also, what about the lights for the power windows, fan controller etc? how many/what size lights are available for those?

thanks everyone!
Joe
 
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