"Most of what passes for legitimate entertainment is inferior or foolish and only caters to or exploits people's weaknesses.
Avoid being one of the mob who indulges in such pastimes. Your life is too short and you have important things to do. Be discriminating about what images and ideas you permit into your mind.
If you yourself don't don't choose what thoughts and images you expose yourself to, someone else will, and their motives may not be the highest.
It is the easiest thing in the world to slide imperceptibly into vulgarity.
But there is no need for that to happen if you determine not to waste your time and attention on mindless pap." - Marcus Aurelius
...someone has finally clarified this phenomenon! Now I understand why I've had an aversion watching TV and movie-going for several decades, even though I myself never understood it. It's bullshit time-wasting entertainment, with very little value for self improvement. Marcus Aurelius finally helped me to grok it.
One of my colleagues mentioned that his son-in-law was cleaning out an old shed on his grandpa's property, and found a radiation detector inside the shed. He asked if I was interested in it and showed me a photo. After a quick look at the image, I said "hell yeah!" (because I'm a fool for old techno-junk), and we agreed on a reasonable price.
The title of the post is a bit misleading - the detector is not new, it's just that I am the new owner. The radiation detector is a 1955 vintage "Professional Model 107B" Geiger Counter. In the original box! The cost of one of these new in 1955 was $138. This would cost $1395 in 2022 dollars - which is a fair bit of cash.
Below: As delivered. It needs a little work outside to be ready for the knick-knack shelf in the office, and a bit more work inside to see if it would actually work.
Below: Yep it's a Model 107B.
There is a nice single-speaker headset to plug into the chassis so you can hear the clicking, complete with cloth cord. The cord is covered with some kind of fuzzy dust at this time.
Below: On the side is a small disk clipped to the chassis. I suspect that this is a radioactive source which would have been used to test and/or calibrate the instrument. I'm leaving this out in the garage until I take some readings on it with a modern radiation detector.
The G-M (Geiger-Mueller) tube is really old-school. The tube is enclosed in a very heavy chrome-plated shield to prevent beta particles from entering. If desired, the top portion of the tube can be rotated after loosening a thumb-screw. This exposes the tube, and allows beta particles to enter it. If the window is closed, the detector will only measure gamma radiation. If the window is open, it will measure gamma plus beta.
The guts of the detector are a bit primitive. Some of the wiring is point-to-point, and other bits are on a circuit board. It was made during one of those periods in time where things were still hand-assembled, but also moving in the direction of modern circuits.
Below: Yes it uses vacuum tubes! It also uses a 22.5 volt battery, two 45 volt batteries in series to get 90 volts, and two "D" Cells. There is an issue at the bottom right of this photo...
Unfortunately at some point, one of the "D" cell batteries leaked electrolyte and destroyed an end of one of the battery clips. The left battery holder should also have an end clip at the top. I'm pretty sure that I can use the right battery holder as a template and make a replacement from sheet metal.
It came with the battered bottom half of the original box, which is also sorta neat. You can find these in pristine condition for a very reasonable amount of money, if you are inclined to have your own working vintage radiac. The real problem would be locating batteries. I'll probably just rig up temporary 90 volt and 22.5 volt DC power supplies to see if it will work, then put it on display in the office museum.
I was able to locate a Model 107B user manual (pdf) without too much difficulty, and it also contained wiring diagram, so that was nice! It should not be a big deal to get this working - pretty simple circuits.
Any work I do on this thing will probably be post-retirement. I've got many other projects closer to the front burner, so this will go under the work bench for right now, next to the old vacuum tube tester. If you are inclined to own one of these vintage devices, you can find one in a variety of conditions and prices on eBay.
UPDATE 18 October 2022:
Yes, that little disk is a radioactive test source. It was giving a reading of 80 counts/minute on contact with the little detector. Not exactly a strong source.
The source has likely decayed significantly since it was made, and no longer has the strength that it once did. According to the manual linked above, the disk is stamped with the strength of the source, in milliRoentgens. Unfortunately, I took the reading counts per minute, not mR. On the back side is a window so that you can see the tiny source. I would guess that 80 CPM is roughly 1-2 milliRoentgen.
13 milliRoentgens is a pretty strong source to release to untrained civilians, in my opinion. Fortunately it's settled down quite a bit over time.
Let's see if we can math this out, and figure out if it's making sense. Look back at this post. There are a couple of equations to help us figure out how much something has decayed. We will use this one:
N(t) = No (1/2)(t/t1/2)
Where:
N(t) = Current radioactivity
No = Original radioactivity - (the stamp on the disk says 13 milliRoentgens)
t = elapsed time (It was sold in 1955 and it's now the year 2022) = 67 years
t1/2 = the half-life of the radioactive substance - and here we have to make a guess what substance it is.
Cobalt-60 and Cesium-137 are the most widely used radioactive sources in general use. Others are available, but they are not common, and some are alpha particle emitters, which this detector is not designed to pick up. So, it's likely one or the other of these.
I'm going to assume it's Cobalt-60, with a half-life of 5.27 years. Cesium-137 could also be the material, but it has a half-life of 30.05 years, and I suspect it would have a higher reading. We can do both calculations.
For Cobalt 60 = 13 milliRoentgens x (1/2)^(67/5.27) = 0.00195 milliRoentgens
For Cesium 137 = 13 milliRoentgens x (1/2)^(67/30.05) = 2.77 milliRoentgens
OK so it looks like I guessed incorrectly. Cobalt-60 would not really show anything above background at this point, where Cesium-137 would still be rocking it a little, which is exactly what we are seeing.
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