> If you're running the LEDs on 120vac, the voltage drop needed is much larger.
The 60W equivalent I just took apart had a full 14 LEDs in series but still used a PWM controller. It took 80 volts DC to get the LED's to their proper brilliance. So just a small resistor will do. This is just the metal disk with the 14 LEDs all in series, no other electronics. What was interesting was that 3 came on at around 15 volts, then more and more came on as the voltage was raised. And they shifted back and forth at various levels until they were all on. Since the bulb was rated at 9 Watts, and assuming 80% PWM efficiency, then I assumed the LED's were rated at 60 mA. And that took 80 volts. All the flashing back and forth as each began to illuminate surprised me. It was almost as if there was a threshold effect. As a new LED decided to illuminate, then the series string suffered due to the greater current and so all the other LED's adjusted. Some ablve and some below threshold. All being in series, it looks like there is a significant variability in their characteristics. But once I hit 80 volts the current above that was linear. But at 80 is also where it got to 60 mA and I did not go much higher. I was using a regulated variable DC supply with no series resistor (Supply was current limited at 120 mA). PS, this divides out to be about 5.7 volts per LED. Much higher than the 2.8 mentioned? Bob _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
