Yesterday, 12:26 PM
(10-01-2025, 10:24 PM)John Cornforth Wrote: Regarding LED stop and tail lamps. The ones from some suppliers consist of a single LED, with two different value series resistors to give a high current for stop and a lower (= dimmer) current for tail. That's all fine and dandy, but there is an increased chance of backfeeding and odd effects with this simple setup, especially if the car has a mix of LEDs and filament bulbs. In my setup, I resorted to adding series diodes in the wiring to prevent back feeding.The reproduction Ruby rear lights we have were so poorly made that the contacts - even with filament bulbs - were hopeless. I ended up soldering the wires to the bulbs using a short length of cable connected to the loom with a "screw connector" so the bulb could be changed easily. I once had a similar problem with a set of trailer lights - not the contacts but the badly-made bulb holders breaking away from the housing. The cable and solder trick solved that one, too.
Another effect is that if bulbholders are not in the first flush of youth, their slightly tarnished connections may work fine with filament bulbs as the higher current tends to "wet" the contact. I'm uncertain of the exact mechanism, but possibly a bit of micro-arcing burns through the tarnish. If you use lower current LEDs contact may become less reliable, especially if the "bulbs" have hard nickel contacts rather than the traditional more accommodating soft solder. The cure is thorough cleaning or using new holders.