WE NEED SPECIFICATIONS
FOR COLORED LIGHT BULBS


WHAT DO WE NEED?

We need the ability to measure standard values for colored light:

We also need to know what kind of power supply the bulb has or needs:

We also need a measure of the life of any lightbulb - one that actually works:


WHY DO WE NEED IT?

People do not know what they are getting when they buy a colored light bulb.

There are a lot of uses for colored light bulbs other than illumination at a party:

Many of the colored light bulbs offered for sale do not produce light that is usable for many of these purposes. The page author has found at least 4 different kinds of colored LED light bulbs on the market:


WHAT CAN BE DONE?


WHAT CAN BE USED?

There are several ways this information can be measured:

CIE map

Color Map


THE BULBS

Appendix 1: Comparing Colored LED Bulbs

Here are the approximated values of various brands of colored LEDs:

COLORED LIGHT BULB PROPERTIES

BRANDLABEL
COLOR
BRIGHT
chromen
HUE
nm or K
SAT. %
or CRI
PSEUDO SPECTRUM SUPPLY OR
BALLAST
COMMENT

                                                     

Feit Daylight 450 lm 5000 82

                                                     

Switching Reference white LED (note spectral gaps)
Feit Red 115 610 90

                                                     

Switching Useful as primary red
Illumin8 Red 68 620 95

                                                     

  Narrow band - useful as primary red
Utilitech Red 63 620 95

                                                     

  Useful as primary red
Zilotek Red 104 620 80

                                                     

  Wide-band simulation of incandescent
Christmas Valley Red 4 620 97

                                                     

Bridge Narrow band - useful as primary red
Great Value Red 79 595 30

                                                     

  Filter cap on white LED
Feit Orange 103 590 85

                                                     

Switching  
Illumin8 Orange 45 590 95

                                                     

  Narrow band
Utilitech Orange 56 590 95

                                                     

   
Feit Yellow 131 577 80

                                                     

Switching  
Illumin8 Yellow 47 580 95

                                                     

  Narrow band amber - dichromat simulation use
Utilitech Yellow 63 575 90

                                                     

   
Christmas Valley Yellow 4 577 95

                                                     

Bridge Narrow band - useful as monochrome yellow
Great Value Yellow 435 575 30

                                                     

  Filter cap on white LED
Feit Green 182 520 90

                                                     

Switching Useful as primary green
Illumin8 Green 123 500 90

                                                     

  Narrow band - useful as primary green
Utilitech Green 156 500 90

                                                     

  Useful as primary green
Zilotek Green 113 530 40

                                                     

  Wide-band simulation of incandescent
Christmas Valley Green 12 510 90

                                                     

Bridge Narrow band - Useful as primary green
Great Value Green 51 500 30

                                                     

  Filter cap on white LED
Feit Blue 79 480 70

                                                     

Switching Useful as cyan
Illumin8 Blue 64 470 80

                                                     

  Narrow band - useful as primary blue
Utilitech Blue 42 470 85

                                                     

   
Zilotek Blue 17 440 35

                                                   

  Wide-band simulation of incandescent
Christmas Valley Blue 5 460 87

                                                     

Bridge Primary blue - Case fluoresces dimly yellow
Great Value Blue 28 440 20

                                                     

  Filter cap on white LED
Utilitech Purple 76 -560 55

                                                     

   
Utilitech Pink 113 -500 50

                                                     

   
Great Value Pink 113 -500 50

                                                     

  Filter globe on white LED
BRANDLABEL
COLOR
BRIGHT
chromen
HUE
nm or K
SAT. %
or CRI

                                                     

SUPPLY OR
BALLAST
COMMENT
PSEUDO SPECTRUM

For white lights:
- The BRIGHT column contains lumens, not chromens.
- The HUE column contains color temperature, not wavelength.
- The SAT column contains the Color Rendering Index (CRI).

For colored lights:
- The HUE column is negative if the hue is nonspectral. See the CIE color map above.

Other brands:
- The Enchanted Forest C9 and C7 lamps are the same as the Christmas Valley C9 and C7 lamps.


Appendix 2: Measuring LED Bulbs

Here us the procedure to measure the various parameters of colored LEDs:

Preparing:

  1. Get the needed equipment:
    • A computer with a spreadsheet (for recording the data and making the calculations)
    • A room that can be darkened
    • An adjustable lamp or stand with the socket for the bulbs to be tested
      (it should be capable of being rotated to present different parts of the bulb to the light meter)
    • A light meter that reads footcandles or lux
    • A small light used to read the light meter, placed where it will not affect the reading
      (the page author used light from the computer monitor and a cardboard baffle to keep this light off of the photocell)
    • A measuring stick calibrated in US and metric units.
    • A pair of Diffraction Grating Glasses (sold in science and novelty stores)
    • If measurements of how much power the bulb consumes are needed, a wattmeter is a good idea. A good choice is a Kill-O-Watt consumption meter. It can measure watts, volt-amps reactive, and power factor.
  2. Set up the equipment:
    • author's setup Determine whether or not the light meter uses footcandles or lux.
    • Determine which method will be used to measure and calculate the amount of light.
      • Meter uses footcandles, set up for footcandles
      • Meter uses lux, set up for footcandles
      • Meter uses lux, set up for lux

      Setting up for footcandles makes the setup much smaller.

    • Find out whether the sensor of the light meter will face horizontally or vertically when it is placed on a stable surface.
    • Arrange the light meter and the lamp so the lamp is the proper distance away and is located perpendicular to the surface of the photocell on the light meter:
      • Space them horizontally if the meter looks horizontally.
      • Space them vertically if the meter looks vertically.
      • Space them exactly one foot apart to set up for footcandles.
      • Space them exactly one meter apart to set up for lux.
      • Place a wedge, box, or prop under the light meter if the meter looks horizontally and the lamp is higher than the meter.
    • The page author's setup is shown at right.
      • The page author was lucky to find in a flea market a working Weston Electrical Instrument Corp. model 756 footcandle meter. It was manufactured in the 1930s and 1940s for stage lighting use.
      • It has a separate sensor head on a cable. Two 1.5"-diameter color-corrected selenium cells are in the sensor head. Amazingly, it has retained its calibration after all of these years.
      • The carpenter's square is bolted to the board. It holds up a clamp-on light (with reflector removed) and shows the height of the bulb above the sensor.
    • Make sure the light from the computer monitor and the light from any light used to read the light meter do not illuminate the photocell.

    Be sure the area can be darkened.

  3. Calibrate your setup with several known bulbs:
    • Calibrations (sample using footcandles)

      Use the procedures below under the headings:
      - Get information from the bulb
      - Take readings from the bulb
      - Do the calculations

      Calibration: Meter uses Footcandles, Set up for Footcandles
       A BC D EF GHI
      1PRODUCT fccd nom lm or cr shad angsphere difference unshaded partbright portionlm or cr
      2FEIT 40 DL 450 lm 5757 716 1500.741181 7.909390.62941451
      3Formulas for above 57= B2 = C2 * 4 * PI() 150= 1 - COS(E2 / 2 * PI() / 180) = 4 * PI() - 2 * PI() * F2= G2 / 4 / PI()= D2 * H2

      The results match the bulb within a small error.

    When in doubt, experiment. Adjust the lamp angle and the entered shadow angle.

Collecting the Data:

  1. Get information from the bulb:
    • Read the bulb package for brand and product identifying information.
    • Read the package for any luminance, color, and power consumption information.
    • Measure the angle θ, with the vertex at the center of the bulb globe or light emitter (if visible), of the portion that does not emit light (the base) from edge to edge.
  2. Take readings from the bulb:
    • If reading power consumption, connect the bulb to power through the wattmeter.
    • Adjust the orientation of the bulb so the direction to the photocell is approximately halfway between the edge of the base and the apex of the bulb. This usually gives the best reading.
    • Adjust the location of the bulb so the nearest light emitting part is the required distance to the light meter.
    • Take the reading.
    • Take readings from the wattmeter (if used).
    • Look at the bulb through the diffraction grating glasses from a distance of at least 10 feet and note any gaps or bright lines in the spectrum. Compare it to the spectra on this page.
  3. Do the calculations:

    Put one bulb in each row of the spreadsheet.

    Enter the following in the spreadsheet:

    • Cell A - The make and name of the lamp
    • Cell B - The light meter reading (in footcandles or lux)
    • Cell C - Calculate the number of candelas.
    • Cell D - Find the nominal lumens of a spherical source by multiplying by 4π.
    • Cell E - The "shadow" angle of the nonluminous zone from edge to edge
    • Cell F - Find the sphere difference by subtracting the cosine of half the shadow angle from 1
      (the spreadsheet requires radians, so the angle is multiplied by π / 180).
    • Cell G - Find the unshaded part by subtracting 2π times the sphere difference from 4π
    • Cell H - Divide the unshaded part by 4π to get the bright portion.
    • Cell I - Find lumens by multiplying nominal lumens by the bright portion.

    When dealing with colored light, substitute the proposed chromen unit of measure for the lumen.

    • Footcandle Calculations

      The setup was purposely designed so the number of footcandles is equal to the number of candelas.

      Meter uses Footcandles, Set up for Footcandles
       A BC D EF GHI
      1PRODUCT fccd nom lm or cr shad angsphere difference unshaded partbright portionlm or cr
      2FEIT 40 Red LED 14.514.5 182 1500.741181 7.909390.62941115
      3Formulas for above 14.5= B2 = C2 * 4 * PI() 150= 1 - COS(E2 / 2 * PI() / 180) = 4 * PI() - 2 * PI() * F2= G2 / 4 / PI()= D2 * H2
    • Lux Calculations

      The setup was purposely designed so the number of lux is equal to the number of candelas.

      Meter uses Lux, Set up for Lux
       A BC D EF GHI
      1PRODUCT lxcd nom lm or cr shad angsphere difference unshaded partbright portionlm or cr
      2FEIT 40 Red LED 14.514.5 182 1500.741181 7.909390.62941115
      3Formulas for above 14.5= B2 = C2 * 4 * PI() 150= 1 - COS(E2 / 2 * PI() / 180) = 4 * PI() - 2 * PI() * F2= G2 / 4 / PI()= D2 * H2
    • Lux Meter With Footcandle Setup Calculations

      The setup was designed so lux must be converted to footcandles to get the number of candelas.

      Meter uses Lux, Set up for Footcandles
       A BC D EF GHI
      1PRODUCT lxcd nom lm or cr shad angsphere difference unshaded partbright portionlm or cr
      2FEIT 40 Red LED 15614.5 182 1500.741181 7.909390.62941115
      3Formulas for above 156= B2 * 0.0929 = C2 * 4 * PI() 150= 1 - COS(E2 / 2 * PI() / 180) = 4 * PI() - 2 * PI() * F2= G2 / 4 / PI()= D2 * H2

    When in doubt, again experiment. Adjust the lamp angle and the shadow angle. The lamp may have an unusual emission pattern.


Appendix 3: About Footcandles, Lux, Candlepower, Candelas, and Lumens

candelas and lumens Here is the explanation of these units of measure:

COMPARING UNITS FOR MEASURING LIGHT
VALUE UNIT ABR QUANTITY MEASURED SYSTEM QUALIFYING FACTS RELATION
Illuminance Footcandle (fc) Light striking a surface US   lm/ft2
Illuminance Lux (lx) Light striking a surface Metric   lm/m2
Luminous intensity Candela (cd) Light emitted in one direction Both Emission in 1-steradian cone lm/sr
Luminous intensity Candle (cd) Same as Candela US Alternate name cd
Luminous intensity Candlepower (cp) Same as Candela US Alternate name cd
Luminous flux Lumen (lm) Total white emission in all directions Both Restricted to white light cd sr
Chrominous flux Chromen (cr) Total color emission in all directions Both Proposed unit for colored light cd sr
Luminous Emittance Footcandle (fc) Light emitted from a surface US Includes surface-reflected light lm/ft2
Luminous Emittance Lux (lx) Light emitted from a surface Metric Includes surface-reflected light lm/m2

Understanding the relationships between these units is essential.



LINKS