Cheap LED and incandescent light bulb comparison

In a hope for cutting electical energy bill a little and for test purposes I've bought recently few cheap ($7 including taxes) LED lamps. They are direct replacement for 230V E27 and E14 light bulbs. They are produced (or distributed?) by TelForceOne, known in Poland for cellular phones batteries and other accessories and branded as forever light.

Declared parameters:

  • 24 LEDs SMD5050 (easiest to verify)
  • 370 lm light stream
  • 50000 hours lifetime
  • weight: 80g - they seem heavy (especially considering small size) and solid indeed, white collar is made of ceramic material, bulb is made of glass (or at least very similar material)
  • 120 degree light angle (solid angle units in description would be more proper but less comprehensible)
  • 5W power consumption
  • intended to replace 40W incandescent light bulb

Here is quick comparison of light generated by 60W incandescent bulb and LED lamp. Each set is made with same time/aperture/ISO set (but these settings are for comparison purpose only). Unfortunately I forgot to switch white balance to manual, so these photos could not help with comparing light spectrum.

60W  incandescent bulb:


Difference in light angle is clearly visible above.

40W incandescent light bulb (E14, matte) vs LED lamp:
40W incandescent:


In my personal perception I would rate these LED lamps slightly lower that as 40 W incandescent light bulb replacement. That may be effect of narrow angle though, single LED lamp with narrow angle could not illuminate room in a similar way that traditional bulb does, there is high contrast between front and back side of LED lamp and in general I think they are worth a try - I'm going to use them in combination with "normal" bulbs.
Of course they can not get hot, but they can reach moderate temperature - I would suppose that 1-2 W is dissipated as heat.
Direct photos of LEDs at work:

While taking last photos I was clearly seeing flickering on camera screen. Light flickering is not visible by naked eye, but I recorded it with oscilloscope using (oh irony) LED as a photosensor/photogenerator:

Flickering is clearly visible and it's frequency is 100 Hz. GND level is in the middle and this is DC coupling, so flickering variation is nearly 100% of maximum output. I assume that these lamps are not using any DC/DC converter (which may be a plus when considering expected lifetime), but LEDs are connected in series and driven directly by full bridge with some current limiter. Flickering may be another reason for using these lamps in combination with traditional incandescent bulbs. If you're interested - with same method no flickering is recorded when using incandescent bulb.

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