That’s like the bulbs used in backlit displays. I have some that are smaller than 3mm LED lighting one display. It reminds me too of EL backlights which were also quite common.
Yes, they were used in a lot of the items you all mention. Medical equipment, model railroad locomotives, panel lights…. But if you were to walk up to a counter at an electronic supply house, what would you ask for?
These bulbs were used back when there was no other option for a very small light source.
These bulbs are not to be confused with a “Wheat Lamp”, named after it’s inventor, Grant Wheat.
Those lamps were designed for underground mining. Here is the Wikipedia Article on the Wheat Lamp.
Yes, this is a heat sink. The question is, were was the heat coming from and how was this used.
(I could be wrong, but I don’t think Google will help you on this one.)
Before I posted that pic I searched the Internet as though I didn’t know what it was. I could find nothing. Congratulations on your voluminous knowledge.
Creepy looking thing, isn’t it? I can’t imagine that they’re terribly durable. It says these were used in electric railroad locomotives… seems like a harzardous cleanup in the event of a collision.
:weary: For some reason I thought you were saying the heatsink was used with the bulb. As odd as that would be.
Of course I was reading things you never said.
I believe we have some of those lamps at my company's other office. They were still being used up until late last year! I was trying to push them toward a more modern cap lamp so as to drop the weight of that darn big battery on their side! Here is a pic of the lights and the charging station at our other office (pic taken 1 1/2 to 2 years ago):