I bought this Philips lamp expecting it to have a switching converter inside to drive the LEDs, but it actually uses a fairly chunky capacitive dropper to limit the current through four large LEDs that I think contain four chips each. The most unusual things about this design are the use of two parallel current limiting capacitors to make up an odd value to suit the load, the four chip LEDs and the use of a small inductor for transient suppression.
I'll apologise for inadvertently saying the 56 ohm resistors were in series when they're in parallel to make an equivalent resistance of 28 ohms. I also managed to give the inductors rating in Farads at one point. DOH!
I'll apologise for inadvertently saying the 56 ohm resistors were in series when they're in parallel to make an equivalent resistance of 28 ohms. I also managed to give the inductors rating in Farads at one point. DOH!
Doesn't the inductor also contribute to the voltage divider as an inductive dropper (please check the values)? Else I could imagine that it shall reduce idle power by pushing in the opposite direction than the capacitors.
Thank you Clive, I always enjoy seeing your earlier videos.
Mask the front of the LED array. Use polarized filter on magnifying element. You can count bands to get # of LEDs.
Philips to me is a bad bad brand. But only as far as CFL's go. So they've been on my do not buy list for quite some time. GE no problem but Philips CFL's? 2-3 months tops. So far longest lasting Vanity CFL's were from "Globe" that was the brand until our local HyVee re labeled them to HyVee and then they didn't last as long either 🙁 so now TCP or Feit and those are going bye bye for TCP LED vanity's. But everyone has their lemons and not all are the same either 🙁
I've got 2 of these lamps. One of them already died within a year. I took it apart and checked the components. There where no visual defects, but the 10 ohm fuse resistor was not conducting. It seems that it is blown.
Bigclive, correct me if I am wrong but I regarded these dropper circuits as cheap dangerous Chinese power supplies.
If Philips think it's a good circuit idea then it must be safe to use ?
I can't understand the purpose of using 56-ohm resistors, I mean why using them if the capacitors already doing the job?
Could you do a video working out the values in reverse? So start with an LED and then calculate the values.
By the way i am trying to make 12w bulb with 0.2W led 60Nos. and Mpet value-2.2uF/450V and ELcap value-47uF/250V
I Have 60Led in series circuit. can you please tell me which mpet i should try. I am currently using 2.2uF but my both capacitor burnout in 2-3 Months. I want this circuit to work more time can you please help me with some calculation about which Mpet and Elcap i should use.
choke is to make power factor close to 1
Very interesting – I have a led light pcb with 26 leds and I measured a voltage drop of 70v and a current of 100 mA but how can I test it without blow up everything.
have you any idea where is it possible to buy such a small capacitors? I check on ic supplier and all capacitors (X2) are bigger then those.
Thanks for this – interesting. I have measured the actual power consumption of these lamps and they appear to far exceed the 2W stated consumption. It seems a decent switching converter would be far more efficient?
you can just do a decap on the phosphor slicone and find out how many chips beneath.
I think, that coil is for reduce reactive power .
I think the inductor is to limit inrush current if the lamp is turned on at the peak of the mains cycle. You have quite a high value dropper capacitor and only a 10 ohm resistor in series which won't limit the inrush current by very much.
Yellow purple brown on an inductor is 470uH.