I was going through some of my old parts

I’m not sure if these are the same kind. The ones I have aren’t neon either.

We knew them as “grain of wheat bulbs”.

firefly?
rice?
wheat?

Reminds me of the neon bulbs found in the old type of voltage testers that glowed orange

How old are you Allan?

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.)

Looks like a heat sink for TO-5 transistors…

Thats a heatsink for the bulb…?

I thought you might be the one to get it.

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.

I will post another tomorrow.

I also knew what a grain-of-wheat/rice bulbs was… :party:

Now what’s this little beastie (BTW, I’ve actual used them before)…

I like this thread.

texaspyro, is your lab full of lightning conductors, knife switches, oscilloscopes and rotary steam balance valves? and do you have an igor?

That looks like a mercury rectifier.
Sadly, I had not yet the opportunity to see one in real life.

However, It looks like a lightbulb designed by Benoit Mandelbrot :bigsmile:

I gotcha! :wink: That heatsink does sorta look like a pill for an LED! When I came across that the other day, that is EXACTLY what crossed my mind!

The rules are, before someone can post another pic, the previous pic has to be identified.

I’m 67 years now and have been working with electronics since the mid 1960s.

And the next picture does look like a mercury rectifier. We had many of them in motor speed controls for Navy surplus Monarch lathes.

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.

Embedding disabled on the Mercury Arc Rectifier video
http://www.youtube.com/watch?v=yjMZ5qtyCU

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):

-Garry

It amazes me how sometimes “old tech” has an ability to hang in there when you would think something else would replace it.

Well this is typical in the mining industry (at least this is what I see and hear). Many things are still done the old fashioned way with old technology. Even when you try to push the new technology as being better, more productive, less downtime, etc . . . they are still reluctant to change! My co-workers now use Li-Ion powered LED cap lamps. I haven't seen them yet, but from what I hear the battery is built into the cap lamp assembly and is charged inside (i.e. battery is not removeable). I think they only put out about 150 lumens (I couldn't find LED cap lamps certified for u-gnd use which had higher output), but they are rated for over 8 hours continuous use which is the most important consideration. I would love to see these new ones and see what the beam is like and what the tint is like. I'm willing to bet it's a very throwy beam with nasty cool white tint! One of the issues is that sometimes (not all the time) the cap lamps need to be "certified" for use u-gnd and therefore your stuck with what is available!

-Garry

I would think the biggest concern in a mine would be sparks. With all that coal dust and perhaps flammable vapors. Lead-acid batteries just don’t sound that safe to me. I would think that what you would want is an integrated light and battery, perhaps hermetically sealed so that there would be no sparks. Charging would be done above ground.