Hi, everybody!
I’m from Bulgaria. There is an V-TAC LED bulb brand on the market. I have bought several LED bulbs before two years. The price then was 6 EUR for VT-1864 model.
Parameters of the bulb are:
100-240V, 50/60Hz, E27, 12W, 1055Lm, 4500K, 200°, 72mA
The weight of the bulb is 160 grams.
I have measured parameters below with a PEREL E305EM5 Energy Meter
Cold Bulb | 231 V | 0.06 A | 11.6 W | cos θ=0.84 |
After 1 hour of work | 233 V | 0.06 A | 10.7 W | cos θ=0.76 |
I have measured the flicker of the bulb with a TEMD5510FX01 photodiode and Philips Oscilloscope PM3215.
Percent Flicker = 50% - quite a few.
The illumination, which I have measured by MASTECH MS6610 lux meter with a distance of 2 meters from the bulb is 100 lux.
The light is neutral white, corresponds to 75 watts incandescent bulb and the room is illuminated well…
I have measured the temperatures of the LED’s Solder-Point Temperature and bulb housing with a thermocouple K type.
Ambient Temperature - (Ta) = 17°C
Solder-Point Temperature - (Tsp)
Temperature of the Housing of the Bulb - (Th)
Work Time | 15 min. | 30 min. | 1 hour | 2 hours | 3 hours | 5 hours |
Tsp | 63°C | 76°C | 83°C | 85°C | 86°C | 88°C |
Th | 43°C | 55°C | 62°C | 64°C | 66°C | 68°C |
Ta | 17°C | 17°C | 18°C | 19°C | 20°C | 20°C |
There are 27 LEDs type 2835 on the Metal Core PCB. Every LED is made from 2 chips serially connected. The LEDs are connected in three parallel groups. Each group consists of 9 LEDs connected in series. Voltage is 54.5 V , Current is 187 mA in cold LEDs.
This is the aluminium housing covered with ThermoPlastic.
Bulb’s socket - E27 EDISON Screw.
Plastic cap on the bulb.
Top of the LED Driver. Two electrolytic capacitors are 105°C, Low ESR.
Bottom of the LED Driver. The IC on the PCB is BP2325А. The BP2325A is a high precision non-isolated buck driver with active PFC, specially designed for universal input offline constant current LED lighting.
Conclusion:
The bulbs work well for two years without any defects and problems. Heating of LEDs is within limits. No reduction of the power of light. I think this is a good and usable bulb.