12 October 2018

What are the gizmos inside this sign ?

Inside the golden arches and the nameplate is a series of what appear to be aluminum plates with a regular array of holes.  I'm guessing these must be components of a lighting system (perhaps for LEDs ?), but can't figure out how they work.  Nothing important, but curious minds want to know, and I thought some reader here might have the answer.

Credit: REUTERS/Jonathan Bachman


  1. I'd guess they sandwich the point light source between them and act as diffusers. A burned out bulb would be a dim spot as opposed to a dark spot like a burned out tube light. Just a guess though.

  2. Just my kind of thing to try and research. Here is another McD's sign, and here you an see a mix of bulbs and these aluminum plates. Which leads me to guess like above that they are defusers http://photos1.blogger.com/blogger/5771/1587/1600/McD%20Cropped.jpg

  3. From the photo in the comments:
    The lamps look like 150-Watt-to-250-Watt Metal Halide lamps, which are bright white(4000-degree Kelvin color).
    The rectangular blocks on the vertical braces are the ballasts to operate the lamps.
    From the position of the remaining square perforated plate on the left, it seems that the plates are to dim and diffuse the light (and perhaps the heat) from the lamp where it is closest to the inner surface of the sign.
    Further away, the low-angle light would be more evenly distributed.
    In many signs, made of individual letters, they have historically used coated discharge tubing (think "neon"), shaped to fit inside the outline of each letter. Now, the obvious trend is toward LEDs....
    I would expect that these signs will be rebuilt with LEDs, as those require less than half as much power, and last over twice as long as Metal Halide lamps!

  4. From Wikipedia:

    "An electrical ballast is a device placed in line with the load to limit the amount of current in an electrical circuit. It may be a fixed or variable resistor.

    A familiar and widely used example is the inductive ballast used in fluorescent lamps to limit the current through the tube, which would otherwise rise to a destructive level due to the negative differential resistance of the tube's voltage-current characteristic.

    Ballasts vary greatly in complexity. They may be as simple as a resistor, inductor or capacitor (or a combination of these) wired in series with the lamp; or as complex as the electronic ballasts used in compact fluorescent lamps and high-intensity discharge lamps."

    Thank you to all. I'm always amazed by the readership of this blog. You help me "learn something every day."

  5. Other topic comment. The map in your 'Borderline behavior' post does not include 100 mile radiuses around each international airport. As far as I understand CBP feels those count as well.

    1. from the article at the link: "CBP’s activities “are not geographically restricted by law.” Even beyond the border zone, the spokesperson asserted, Border Patrol agents have the authority to question individuals and make arrests."


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