Re: Dash Led's

["dmc12jp" <hidesuke@xxxx>]

Hello list,

First post to DML and probably the first post from Japan also.

I would like to share my experience of LED conversion. I replaced the incandescent 
bulbs on the A/C panel and in some of the switches on the panel to LEDs. The LEDs I 
used are not the ones from Jamstrait. They were not available when I did the 
conversion two year ago. It would have been much easier with those.

I did this conversion because I was worried about the significant heat that is produced 
by those bulbs. I thought it might even distort the panel in a long run. LEDs draw less 
current so it is good for the car. I estimated the current consumed in the A/C panel to 
be about 1.5A. By replacing them to LEDs it is reduced by a factor of 20. Another 
advantage is that once you replace the bulbs to LEDs you won't need to open it again 
for replacing the bulbs. LEDs will last almost forever. 

I am pleased with the results. It gives much crisper and clearer impression to the 
panel than the original. It is literally cool.

One thing that might be unique to my modification is the use of current limiting 
diodes. They regulate the current to 15mA regardless of the supplied voltage. This 
gives a constant brightness regardless of the condition of the electrical system in the 
car. The drawback is that the rheostat does not have much effect. It does not bother 
me, though since I do not need to worry about the heat any more.

I used 6 hyper-intensity LEDs (2 White, One Blue, One red, Two green) and 2 diodes 
for the A/C panel, One red and one diode for the Hazard switch. In some part, I used 
two or three LED in series with this diode. The voltage drop is different for different 
color of LED, so you need to take it into account when planning the combination. 

I had to cut off the tops of each LEDs a bit for the A/C panel, but I did not need to 
modify the panel at all. Replacing the bulb in a switch is a little tricky. First, you take 
out the switch and open it carefully. You then solder a LED and a diode together, and 
tailor its legs to fit the contacts where the original incandescent bulbs have been. 

I posted the pictures on the web.
http://homepage.mac.com/hokam/PhotoAlbum1.html 

I am sorry for the poor quality of the pictures. They are out of focus. At that time I 
had a very old digital camera which had a fixed focus and it was extremely difficult to 
take such kind of pictures.

Regarding the choice of the color of LED, Mike is right. I should have used a white 
LED for the temperature control part of the A/C panel instead of blue. Experiments 
showed white LEDs give much pleasing color to our eyes. I think this can be explained 
by the fact that the wavelength of color LED is almost monochromatic, whereas the 
coloring of the panel is not. By using a monochromatic light source only a small part 
of the light can transmit. Also the intended color cannot be reproduced. 

Specs of the LEDs I used. The cost of each LED is about 500 yen (= $4) here in Japan. 

White LED --- NSPW500BS
4000 mcd (TYP) 20mA, VF = 4V

Blue LED --- E1L51-3BC02
1800 mcd (TYP) 30mA, Wavelength - 465-475 nm, VF = 5V

Bluish Green --- E1L51-KC0A2-1
3200 mcd (TYP) 10mA, Wavelength - 493-498 mn, VF = 3.2V
(This LED is used for green traffic lights)

Current limiting diode - CRD-153 (15mA)

I hope this will be of some use to you.

Best regards,
Hideki Okamura
Tokyo, Japan


--- In dmcnews@xxxxxxxxxxxxxxx, "Mike" <mquinto@xxxx> wrote:
> The reason why I'm going with white for the greens and blue is, it
seems to show 
up the lens color better than using blue, amber or red led behind it.
I have these 
individual colored led's to play with, but I didn't have green so I
could tell you how it 
might look.