Hi.
Bought this 30Watt
----> **broken link removed**
with 102 leds, supposed to be for 85 to 265 VAC; gives less light than a 15Watt fluorescent CFL.
Supposed to have cree brand leds, but they do not tell the type/model in order to measure/test if the bulb is correctly built/labeled/driven.
Two equal circuits inside are each a 1.5uF/250V capacitor in series with a full wave rectifier to 4.7uF/400V electrolytic filter capacitor feeding series of 51 LEDs, no limiting resistor.
1.5uF at 60 Hertz result in Zc = 1768 Ohms.
A series of 51 white LEDs assumed at 3.3 Vf result in 168 Vf
120V AC after the bridge rectifier and filter are supposed to yield 170V DC
Measured Vf of one LED, shows 2.82V when bulb is lit;
AC supply measured 120.4V;
Capacitor drop measured 20.4V AC.
20.4VAC in 1768 Ohms = 0.011 A
So there is 100VAC / 141.4 V peak into 51 LEDs, resulting in 2.77Vf for each.
Seems LEDs are underdriven.
Do I raise the series capacitor to 2.0 uF for Zc = 1326 Ohm ? Or more ?
Or, eliminate the mains bridge rectifier/capacitor/filter and connect the two sections of 51 series LEDs in counterparallel to mains ?
Or, short circuit a few LEDs to raise Vf and If ?
Or, could the bulb be mislabeled as for 120V and it is intended for 240V ?
Or, what would you do ?
Schematic---->
https://s588.photobucket.com/user/Innernet/media/P1010590_zpsn1ztzgxb.jpg.html?sort=3&o=0