tim_ber
Well-Known Member
Thanks to everyone for the valuable input .
"You will notice the pins on the assembly are labelled "+" and "-", so the complete light is polarised and won't work if wired backwards. Most LEDs will only tolerate a relatively low reverse voltage, but I guess the series connection means they should survive reversal at 12V, so ne need for any diodes.
Hope this helps."
Yes, that makes a lot of sense and explains something else. Last year when I bought a Chinese LED cluster (or a few because they are so cheap) it was sold as a rear tail light.
Of course I discovered it was positive earth so not much good for UK cars.
I opened it up (out of interest as usual) and it was a totally different configuration from the LEDs discussed here - which are as I think (was it Ole Will or Will mentioned?) amazingly summed up correctly (I think - I am still scratching the paint off so I can trace all the copper pathways - but looks like as he has described).
It had two main 'legs' one with a resistor on it and one with an ordinary diode (and this was because - as you have just explained - the configuration was totally different - not a series config - reversing the polarity on that cluster would have damaged it I guess which is why the designers used the ordinary diode).
I never used it in my car because I did not know about resettable fuses at the time (that I learned from this forum) and constant current devices (req'd for when the alternator charges at 14.5V etc that I also learned from this forum) and I wasn't going to risk a fire by using a dodgy LED with no current protection.
I did take the resistor out of it though and used it to replace a filament bulb in a torch. It was run from a source of 6V and I had to stick a resistor in obvioulsy (I used one of the online LED resistor calculators).
Learned a lot here. Many thanks as usual, guys.
"You will notice the pins on the assembly are labelled "+" and "-", so the complete light is polarised and won't work if wired backwards. Most LEDs will only tolerate a relatively low reverse voltage, but I guess the series connection means they should survive reversal at 12V, so ne need for any diodes.
Hope this helps."
Yes, that makes a lot of sense and explains something else. Last year when I bought a Chinese LED cluster (or a few because they are so cheap) it was sold as a rear tail light.
Of course I discovered it was positive earth so not much good for UK cars.
I opened it up (out of interest as usual) and it was a totally different configuration from the LEDs discussed here - which are as I think (was it Ole Will or Will mentioned?) amazingly summed up correctly (I think - I am still scratching the paint off so I can trace all the copper pathways - but looks like as he has described).
It had two main 'legs' one with a resistor on it and one with an ordinary diode (and this was because - as you have just explained - the configuration was totally different - not a series config - reversing the polarity on that cluster would have damaged it I guess which is why the designers used the ordinary diode).
I never used it in my car because I did not know about resettable fuses at the time (that I learned from this forum) and constant current devices (req'd for when the alternator charges at 14.5V etc that I also learned from this forum) and I wasn't going to risk a fire by using a dodgy LED with no current protection.
I did take the resistor out of it though and used it to replace a filament bulb in a torch. It was run from a source of 6V and I had to stick a resistor in obvioulsy (I used one of the online LED resistor calculators).
Learned a lot here. Many thanks as usual, guys.
