Anybody here own a Geiger counter?

About nine months ago I dug up an old FEMA-issue Geiger counter that was lurking in my garage. I did some online research and found a gaggle of information on mods people do to these things. As a result I bought a few more (for parts) from eBay. Now I have a number of Geigers and a few of the high-range nuclear war type units. Fascinating devices!

I'd like to build one from scratch... I must be an electronics idiot, because when I protoboard the schematics I've been finding online, they never seem to work, and I don't have the know-how to reverse engineer the circuit.

Do you find any normal items elicit a response from your Geiger counters, meaning I believe many devices emit radioactivity in very small doses, will it pick that up? We had one at work but I never got to play with it. We built electronics for GENuclear used in nuclear plants and the field returns had to be checked for radioactivity.

geepondy said:

Do you find any normal items elicit a response from your Geiger counters

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Actually, my FEMA counter didn't really get much of a response from anything until I replaced the tube. The original Geiger tube on those things is roughly the same size as two AA cells end-to-end. I bought an LND brand tube for around $125 and machined a new probe housing for it. The new tube is shaped like a hockey puck and was good for HUGE improvement in sensitivity. But then the analog dial (which has tick marks in counts per minute) was rendered inaccurate. So I connected a signal conditioner to the headphone jack; it takes the "clicks" from the headphone jack and shapes them into clean square waves, and then this is routed to a digital counter. That was an idea I stole from makezine.com.

Anyway, there were a number of interesting radioactive items I was able to find with the new tube... granite countertop put out a surprising number of clicks. So did the furnace filter at my folks' house... I asked around and was told this was due to the decay of radon trapped in the dust particles that the filter caught. And you get a surprising number of "hits" from background radiation... just sitting on my desk I get a click about once per minute!

I think a tritium should give you some small reading.
Norm

A good test source would be vintage Fiesta ware pottery and dishes in the red/orange glaze color. Flea markets or eBay are common sources.

Cheers,

Mark

Here is one of my favorite radiological detectors for hobbyists (PC or Mac):

http://www.blackcatsystems.com/GM/geiger_counter.html

Regards,

Mark

You might check out www.unitednuclear.com they have some awsome uranium ore samples among other radioactve sources you could "Play" around with
Nuker-

I got a few geiger counters given to me when our office of emergency services decided to get rid of the old stocks of civil defense gear from the 50's. They were all new in box and worked great. My wife thougth I had snapped a cap when she saw them. It is always fun to freak people out by showing them the reaction to fiesta ware dishes.

Norm said:

I think a tritium should give you some small reading.
Norm

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The beta radiation from the tritium should not pass through glass. I don't get any higher readings from the 16 trits on my Traser... I have Geiger counters at work

Norm said:

I think a tritium should give you some small reading.
Norm

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try bananas next

bannanas and then your smoke detector.

All you need is some KCl (Potassium Chloride)

A.K.A No-Salt or Sodium free salt

You should get a pretty good reading from a shaker or you can buy the KCl that is used in water softeners (bug chunks), about $8 a 40lb bag at Lowes or Sears.

You wont get any reading from a smoke detector unless you do some major surgery on it and destroy it. Even then the reading will be very low if anything at all. Your meter is a gamma detector. Smoke detectors usually use Americium-241 which is an alpha emitter with very weak secondary gammas

I have two from the era of US Civil Defense - the "yellow" CD V-700 and CD V-715. The CD V-700 is working good, the CD V-715 is for very high radiation - I can't test it, I have to wait for the next reactor melt-down . I also have one Eberline E-140N (this one is for sale, if anyone interested), a russian digital "PKC" , TA geiger counter with a scintillation probe, and some other misc stuff. I have also some "check sources" arround, like radium watch hands, a smoke detector and stuff like that. Tritium from a Silva compass gives off some weak radiation - only detectable with a good end-window geiger tube.

Great discussion groups about geiger counters and radiation:
http://tech.groups.yahoo.com/group/geigercounterenthusiasts/
http://tech.groups.yahoo.com/group/cdv700club/

Cool,
My friend says he has one from his grandfather. Now to convince him to get it for me.

In a high school lab, we had a chance to test different materials for radioactivity and one of the things I played with was a Coleman mantel from the early 1980's



Coleman no longer uses Thorium in the mantels today but I think there are some other manufacturers (Colegan or Century) that may have some.

The smoke alarm, my teacher had to disassemble it and bash the smoke sensing chamber open to get to the Americium and there was only a little tiny bit. Even then, the tube had to be positioned very close and directly in line with it to get a reading.

We also had a peice of depleated uranium that was easily picked up about two feet away.

Cool, what's cool also is my friend built a chamber and it makes some gases and you can see the particles go thru the gas.

In my school, the teacher had a chunk of some radiactive stuff in a lead box.

Also, the geiger counter went off even when nothing is around sometimes cause space has incoming radiation.

I have a CD V 700 and a IM 174 radiac meter. The CD V 700 is not calibrated and fun for low level stuff. The side of the meter even has a radioactive source under the sticker on the side for testing. The IM 174 was the meter I used while serving in the army during the early eighties. I recently found one on the surplus market with carrying case. I sent it out to a lab for calibration. Its a high level meter and I have it around "just in case"

I also have a neat matchbox sized nukalert. It monitor 24/7 for 10 years on lithium batteries and rad/hrs are indicated by a series of chirps.

Nice, well if your by me, PM me if you detect radiation levels getting high. I'll try to get out asap.

LESLIEx317537 said:

...my friend built a chamber and it makes some gases and you can see the particles go thru the gas...

Click to expand...

I'm getting old - have I explained this before?

Project #1) In high school I made a sub atomic particle cloud chamber and convinced the instructor I could figure out the speed of the particle.

My thoughts were to measure the length of the atomic particle's trail and then with the speed of the camera shutter, perform the calculations resulting in it's speed.

Well I couldn't get a good picture of the trail (oh, did I mention I was on the photography/year book staff with a full dark room available for my magic?). I ended up using a little/very tiny strand of a white thread/string, blurred up the pic a bit and then of course made my measurements & calculations for credit...BINGO!!

OFF TOPIC - but still in the "snake-oil mode":

Project #2) Convinced the instructor I could take a pic of a shattering light bulb after a hammer struck it. I had electrical contacts on the light bulb & hammer leading to a flash. Thoughts were that the flash would go off & freeze glass particles in flight after the hammer struck & set off the flash.

Well, I wasn't actually successful - so I glued pieces of shattered light bulb to black cloth...positioned the base of the shattered bulb, the hammer - took my pics & worked my darkroom magic...BINGO!!

Project #3) I also convinced the instructor I could take a pic of a bullet's flight fired out of .45 cal Colt. I glued a .45 bullet to a piece of non-glare glass with the gun barely visible in the side of the pic...BINGO!!

Of course the pic was too perfect, no motion/blurring or gas exhaust from the gun. I guess I took my "creativity" too far as he didn't believe it, didn't believe one his high school students had the technology to achieve those results. He said he'd give me credit if I explained how I did it all.

Being the "HONEST" person that I am - I indeed told him everything and he did give me credit!

Thank you Mr. Murphy R.I.P.

Hello,

I own a little lot of geiger counter and dosimeters, all them working. You can test your also with background radiation. If any admin allow me, I can post the URL's to some Yahoo groups about Geiger counters and radiation. Maybe if you have an old watch with radium hands, you can use it.

The beta radiation from the tritium should not pass through glass. I don't get any higher readings from the 16 trits on my Traser... I have Geiger counters at work- I agree 100%, the beta radiation is of very low energy... but x-rays due the crystal of the vial pass the coating. If you use a mica pancake probe, you will be able to measure the radiation, and maybe with a digital geiger you can do it also with a beta probe.

GCE: http://tech.groups.yahoo.com/group/GeigerCounterEnthusiasts/
CDV700Club: http://tech.groups.yahoo.com/group/CDV700CLUB/
HomeRadLab: http://tech.groups.yahoo.com/group/HomeRadLab/

Antonio