When braking, the brake bulbs glow all the time and are bright enough. But the turn signal bulbs ? even in my 2- bulb-chambers-setup (see foto 3) ? need too long to glow up and fade too fast. This proved to be too weak in bright sunny days to be considered safe. I had a couple of bad traffic situations because of this. I now wanted brighter LED brake and directional lights.
I got my car 6 V / minus grounded. In fact, the regulator / generator combo delivers between 8.5 and 4.8 V depending on rpm, load and temperature of the regulator unit. Because of this, a simple resistor and LED setup proved impossible: I tried 3.5 ohm and had the resistors melting their solderpoints ? even if soldered to a big cooling brass sheet.
(Picture 1 + 2):
Only a voltage regulator could deliver constantly 2,6 V with any entry from 9 to 4 V.
(Picture 3)
Earlier, our authorities had me to separate back lights and brake lights to get enough brightness. So I changed to 2 bulb sockets with a brass separation wall and aluminium foil reflector (beware of shorts!!). To avoid making new holes, I fixed these with 2 copper stripes with the original skrew.
(Picture 4):
I bought some inexpensive 12 V additional brake lights from a car parts shop to get 60 LEDs. I cut perf board stripes to fit into my brake light chamber and put 5 LED in 6 rows for each side with their respective resistors. I soldered all together with a strong copper wire being sure to get a curve and angles between the LEDs.
(Picture 5)
In the free room, I fitted the LED brake light assembly. It is easily removable by 1 skrew (through eye and in nut) plus a plug. The heat sink slips under the bulb socket.
The original sockets with their bulbs are now fixed and wired under my dashboard: Without this, the direction relay gives a much too high frequency as if one bulb where burned?LEDs don?t draw enough current. Above this, with an LED device failing, I just can take the bulb back to its fender socket.
The values of R 1 and Poti have to be tried out.
(foto 6, near Monte Caelo summer 2007)
As I had a spare additional 3rd brakelight, I changed resistors and print board for 6 V use and can just clip it under the trunk lid. There is a plug wired to the brake light cable. For our autobahn speeds, this is necessary against the 140 mph Porsches!
It was a long weekend to try all this out and getting it nicely under bezel and lens.