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
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
