 |
 | Home | Contact Us | FAQ | Search & Site Map | Link to Us |
 | Sign In | Join | Other 45 Sites in Network |
Car Forum / Porsche / Porshe 944 / January 2006Replacing 944 clock bulb with LED - problems dimming?
1986 n/a 944 OK, I did a bit of research - I know you can reach the bulb for the LCD dash clock by removing the glove box liner. And I know I can replace the bulb using an LED with a mini-flange base (I'm thinking blue or red would look nice) by finding a replacement for bulb #2721 . What I don't know is this - The standard setup dims the bulb when the headlights are on (or so I've read; my clock bulb was dead when purchased). What would happen to the LED? Does it dim, does it stay normal, or does it simply not light up? Or does it depend on the LED? Or can I work around by by changing a few things, eg cutting the connection to the headlight switch or something. Thanks for any experiences you can share. I have your answer...the bulb is simply on/off. It actually turns on when the lights are on, because it's purpose is to illuminate the numbers. During the day, with the bulb off, you can see the clock just fine under natural light. So, to answer your question...the led should work fine. > 1986 n/a 944 > [quoted text clipped - 17 lines] > > Thanks for any experiences you can share. > I have your answer...the bulb is simply on/off. It actually turns on when > the lights are on, because it's purpose is to illuminate the numbers. During > the day, with the bulb off, you can see the clock just fine under natural > light. So, to answer your question...the led should work fine. The bulb should come on at full brightness with the ignition, when you switch on the sidelights the backlight should dim slightly. I found a similar bulb but without the plastic holder so I used the holder from the old bulb. Fiddly but not that difficult, just be careful not to break the wires. I bought a pair & used the other to replace the ashtray bulb. Malc. > > 1986 n/a 944 > > [quoted text clipped - 17 lines] > > > > Thanks for any experiences you can share. > "Devils944S2" wrote... > > I have your answer...the bulb is simply on/off. It actually turns on when > > the lights are on, because it's purpose is to illuminate the numbers. During > > the day, with the bulb off, you can see the clock just fine under natural light. Not in the OEM dash clock for a 1986 - dunno if the S2 is different. It's too dark to read, unless you're inches away (hard to drive like that!) > The bulb should come on at full brightness with the ignition, when you > switch on the sidelights the backlight should dim slightly. Right, that's how lit clocks and lit instrument panels in cars normally work. Normally bright so that it's visible with more ambient light, dims at night (when headlights are on) so they're not glaring. > I found a similar bulb but without the plastic holder so I used the holder > from the old bulb. Fiddly but not that difficult, just be careful not to > break the wires. I bought a pair & used the other to replace the ashtray bulb. Yeah, I may be forced to replace it with a regular bulb. But if an LED will dim properly, I'd rather pay a bit extra for the longevity and color :) If you've replaced your dash instrument lights with LEDs, what happens when you use your dimmer? All I've read are something like "you may have problems dimming them" but no detail. I suspect that they won't dim - at a certain threshold, they'll just cut off and I want to confirm before I buy and replace. > > > 1986 n/a 944 > > > [quoted text clipped - 17 lines] > > > > > > Thanks for any experiences you can share. > If you've replaced your dash instrument lights with LEDs, what happens > when you use your dimmer? All I've read are something like "you may > have problems dimming them" but no detail. I suspect that they won't > dim - at a certain threshold, they'll just cut off and I want to > confirm before I buy and replace. LEDs require much less power than a bulb so may remain virtually as bright when the dimming circuit is active. Good luck if you decide to go for it, but imo it's a whole lot of hassle with virtually no gain. The ordinary bulbs last for years & aren't that hard to replace. If you want a colour change or something try a sweetie wrapper or something similar (as a coloured filter) behind the LCD of the clock. Malc. the information in the reply to you is entirely wrong. I have successfully replaced the bulb with LED, I used red because it's better for night vision, butyou can use any color you want. ' The clock has two lighting circuits but one bulb. when the headlights are OFF and the ignitoin on, the bulb is at full brightness and gets connected directly to the 12V power. when the headlights are on, a dropping resistor is inserted in series with the bulb to make it dimmer. I removed the clock, soldered in an LED and dropping resistor, and it has worked for the past 9 or 10 years. this is a lot harder than just replacing a $3 bulb though. >> "Devils944S2" wrote... >> > I have your answer...the bulb is simply on/off. It actually turns on when [quoted text clipped - 47 lines] >> > > >> > > Thanks for any experiences you can share. Bill www.wbnoble.com to contact me, do not reply to this message, instead correct this address and use it will iam_ b_ No ble at msn daught com > the information in the reply to you is entirely wrong. I have > successfully replaced the bulb with LED, I used red because it's > better for night vision, butyou can use any color you want. ' I may be wrong but I thought red is poor for night vision and that green is better? IIRC the human eye collects more information about contrast from the green part of the spectrum which makes stuff easier to interpret against a dark background. It's also the logic behind digital cameras etc using a repeating square grid of one red, one blue & two (diagonally opposed) green pixels. Red dash lights do look cool on Audis though ;-) > The clock has two lighting circuits but one bulb. when the headlights > are OFF and the ignitoin on, the bulb is at full brightness and gets [quoted text clipped - 5 lines] > has worked for the past 9 or 10 years. this is a lot harder than just > replacing a $3 bulb though. If you get the chance do you think you could post a list of components? Or maybe a link to a pic of the back of your clock so we can see how you mounted it? Cheers, Malc. 1, red is best for night vision - you can do the research to verify - the cones are more sensitive at 560 angstroms, a greenish yellow color, but that's not the issue - you want to maintain your dark adaptation, so you want a color that doesn't cause the rods to shut down - that's why submarines and aircraft and whatnot use red for nighttime gauge illumination. 2. list of components - I used a couple of red LEDs (this was a while ago when they were less bright than now) with a resistor in series with each one - exact value depends on the rated current of the LED and the type - for red, there is a 0.7 volt drop across the LED, and I wanted 20 ma, so that's 20ma, 13 volts, and r-e/r = 13/.02=650 ohms - so use 1K or thereabouts to be safe. 560 is another common value if you want to run closer to 30 ma. 3. I disassembled the clock, and glued the LEDs to the plastic light diffuser inside - I did not make them dim when headlights came on. 4. you can now get LEDs with an internal constant current source - these will require no resistor, you can just hook them up to the old light socket. 5. red looks cool, I'd avoid green, you can use white though and it will be kinda like OEM, or one white and one yellow and it will be closer to OEM >> the information in the reply to you is entirely wrong. I have >> successfully replaced the bulb with LED, I used red because it's [quoted text clipped - 24 lines] > >Cheers, Malc. Bill www.wbnoble.com to contact me, do not reply to this message, instead correct this address and use it will iam_ b_ No ble at msn daught com Thanks for the info! > 1, red is best for night vision - you can do the research to verify - > the cones are more sensitive at 560 angstroms, a greenish yellow > color, but that's not the issue - you want to maintain your dark > adaptation, so you want a color that doesn't cause the rods to shut > down - that's why submarines and aircraft and whatnot use red for > nighttime gauge illumination. It's true, red is best for not losing your dark adaptation and the US Army used to use them in field flashlights. > 4. you can now get LEDs with an internal constant current source - > these will require no resistor, you can just hook them up to the old light socket. I was thinking about one of these to make it simpler. Basically, it would be at full brightness, regardless of whether the headlights are on or not? or should I remove the existing dropping resistor? > 5. red looks cool, I'd avoid green, you can use white though and it > will be kinda like OEM, or one white and one yellow and it will be closer to OEM I was about 90% likely to go with red for both the clock and instrument lights (figuring that if the instrument lights couldn't dim with LEDs, at least my eyes would still be adapted to darkness. For the cool factor, 10% thinking about blue :) Last weekend I took advantage of the holidays and replaced my dim OEM instrument cluster lights with white LEDs. Looks VERY nice indeed! The dimmer dial is basically useless, as indicated above. It seems to make for two settings: full bright and if I turn it all the way down 90% bright. I've done a bunch of night driving now and while I do get a bit of a reflection on my windshield, it isn't anything that causes appreciable impairment. Based on that, I would say doing whatever you feel will be coolest is probably the way to go. One bit of advice: they say you don't have to pull the steering wheel off on a 944 to replace the instrument cluster. While technically true, the project is MUCH eaiser and faster if you do. Ok, a second bit of advice: Go with the red or white, avoid the blue, unless this is to be a show car. My CD player has selectable LED lighting. Blue is highly distracting at night out of the corner of your eye. Other colors don't seem to have the same adverse effect on me. > Last weekend I took advantage of the holidays and replaced my dim OEM > instrument cluster lights with white LEDs. Looks VERY nice indeed! [quoted text clipped - 13 lines] > lighting. Blue is highly distracting at night out of the corner of > your eye. Other colors don't seem to have the same adverse effect on me. Cool, thanks, and cheers for the tips. Where did you get your LEDs? So far, superbrightleds.com seems to be the a major player. it's your car, of course, but I find that I usually drive with the instrument lighting as dim as possible, so I can just barely see the instruents - I really don't like it when they are brightly lit. Take this into consideration - the bright instruments and the very dark roadway - you won't see the roadway as well because the instruments will basically partly blind you (or prevent dark adaptaiton) - the clock is a special case, it's far away from your normal field of view, and you can use red and adjust brightness once by changing the dropping resistor (if you use one) or hte LED type. I'd be very reluctant though to have a bright gauge cluster. >> Last weekend I took advantage of the holidays and replaced my dim OEM >> instrument cluster lights with white LEDs. Looks VERY nice indeed! [quoted text clipped - 16 lines] >Cool, thanks, and cheers for the tips. Where did you get your LEDs? >So far, superbrightleds.com seems to be the a major player. Bill www.wbnoble.com to contact me, do not reply to this message, instead correct this address and use it will iam_ b_ No ble at msn daught com > it's your car, of course, but I find that I usually drive with the > instrument lighting as dim as possible, so I can just barely see the > instruents - I really don't like it when they are brightly lit. Take > this into consideration - the bright instruments and the very dark > roadway - you won't see the roadway as well because the instruments > will basically partly blind you (or prevent dark adaptaiton) - I find that the instrument lights are fine as is for night driving on highways through unlit areas. But in my parking garage, or on city streets (or dawn/dusk when there is still ambient sunlight) it' s difficult to read the gauges - too much light from outside, not enough on the inside. I'll try re-silvering the light tunnels first, and maybe replace the bulbs. > the clock is a special case, it's far away from your normal field of view, > and you can use red and adjust brightness once by changing the > dropping resistor (if you use one) or hte LED type. I'd be very > reluctant though to have a bright gauge cluster. I ended up buying a standard (2721) incandescent Sunday (they're cheap, $2.50 US for two bulbs), will pop it in and see how it looks (the bulb was out when I got the car, so I've never seen it in working condition. I might still go red LED later, though. Thanks for the info and comments! |
Reply to this Message |
 Sign In
 Join
 My Latest Posts My Monitored Threads My Blog My Photo Gallery My Profile My Homepage Start New Thread Enable EMail Alerts Rate this Thread
|
©2008 Advenet LLC Privacy Policy - Terms of Use
This website includes both content owned or controlled by Advenet as well as content owned or controlled by third parties.