Posts Tagged ‘Acriche LED’

There remains an issue of flicker and its issues that has been drawn out by a lack of action on the part of our standards and professional organizations. The topic of flicker has been turned into years of discussion, consternation, regurgitation of old information, tests to prove what has already been known for years, and avoidance of conflict. One of my best selling products from the Lumenique Product Center is the Flicker Machine, as simple device for visually detecting and confirming that visible flicker exists within a space or from a source, indicating there is a desire of individuals to know more. I presented a bit on this device and its use here some time ago.

This little spinning wheel tells the story. If you see banding and colorful rainbows, the lights are a flickerin'

This little spinning wheel tells the story. If you see banding and colorful rainbows, the lights are a flickerin’

I have invested my personal time exploring this topic, including participation in the IEEE 1789 committee addressing the risks of flicker, presentations at DOE and other conferences, working with various manufacturers on their line voltage, non-driver products, and personal testing, experimentation and actively living with and under AC LED products.  After more than 6 years of this, one simple question surfaced for me.

If DC and high frequency (>2,000Hz) PWM driven constant current LED solutions produce no visible flicker, why consider a source with greater flicker presence? (more…)

An LED that runs from 120V AC (o0r 240VAC) is an inciting item in the solid-state low voltage DC universe. No driver, no transformer. Just plug it into the house current and let ‘er rip! Available in 2W 65l  (3000K) / 80l (6300K) and 4W 150l (3000K) to 195l (6300K) versions, these devices are fairly powerful and generate good efficacy (between 32 and 40 lumens per watt), not bad, considering there are no other power losses involved from voltage conversion and driver/conditioning. This is roughly the performance of a 50l/w 24VDC CC device operated from a balanced and high efficiency driver/power supply. Not bad.

Color rendering index is 70. At the low end of the good range, and is caused by a weakness in the red end of the spectral distribution. Further, the peak power is virtually right on top of the 575-600 nm of photopic vision.  The result is that the 3000K light looks a bit “White” and less “warm” than one might expect.

To put these to the test, I retrofitted a pendant (in my office), which was originally illuminated with 4 – 75 W Halogen lamps (300 watts for the fixture). I used a total of 8 – 4W PCB Mounted Acriche LEDs mounted to 5W radial heat sinks (32 watts). One set of (4) LEDs are aimed up at the ceiling with customized diffuse parabolic reflectors, the other (4) were aimed down into the glass pyramids. Between the two is a metal plate, painted white. The LEDs were then simply wired into the original luminaires wiring, without even taking it down from the ceiling. The original lamps were housed on glass diffusers, within the glass pyramids and topped by sand etched glass plates. All the remains of this are the pyramids, so the retrofit suffers less diffusion loss.