Mini GM detector

What can you make fit into a mint tin?
Forum rules
This is for things you've managed to miniaturize to the point of slipping into a pocket easily.

Mini GM detector

Postby Joe Jarski » Tue Aug 23, 2011 4:46 pm

I think this fits here - it's probably not high tech enough to be considered "metrology".

Since the topic of little rad detectors has come up again, I figured that I should post some pictures of the one that I made a few months ago (not to mention that Doug has requested it too), which is a little larger than a cigarette lighter. I loaned mine out and have been waiting to get it back so that I could get some better pictures, but for now I'll post what I have.

This is the circuit board minus the GM tube which is a Russian surplus unit. It runs on a single 3V 123A battery. A few things that make it different from some of the others that are similar is that it has a LED bar graph display with the first green LED flashing every count for low level stuff and the last red LED about half lit on the hottest torbernite rock that I have. There's a button for the power switch and a 3 position slide switch that changes from clicks/nothing/vibrate, a la pager motor.
IMG_1478s.JPG
Circuit board with a quarter for reference


This is the unit with the cover off. The GM tube is in front and about 1/4" diameter by 5/8" long.
IMG_1495s.JPG
Detector with the cover off


And the final product. It's 1" wide, 7/8" thick and 3-3/4" long.
IMG_1503s.JPG
Completed unit
User avatar
Joe Jarski
 
Posts: 231
Joined: Thu Sep 16, 2010 8:37 pm
Location: SouthEast Michigan

Re: Mini GM detector

Postby Bill Fain » Tue Aug 23, 2011 8:26 pm

Hi, I think Joe is a little modest on his capabilities here. The counter started out as a rather large "micro" counter. Joe did a "Honey I shrunk the Kids" thing on it and made his own board and replaced everything with surface mount tech. You can tell it's pretty compact in the knife comparison photo. Joe made practically everything. I think he even made the screws. The body was made from a solid aluminum bar stock. It is a very handy item and has verified radioactive items in antique stores rather well. The Chinese have already copied this and I bought mine from a far east trading company. Joe, just kidding about the copy. -bill
micro.JPG
Micro image of original micro counter.
bar_graph.JPG
Happily counting away on fiestaware
scale.JPG
Fits nicely in a knife case
User avatar
Bill Fain
 
Posts: 90
Joined: Sat Jul 17, 2010 10:23 am

Re: Mini GM detector

Postby Joe Jarski » Tue Aug 23, 2011 9:18 pm

Thanks for posting some more pictures Bill - it gives a nice size comparison. I initially built two of these and Bill has the second unit -- you're probably right about the first one being copied in China by now.
User avatar
Joe Jarski
 
Posts: 231
Joined: Thu Sep 16, 2010 8:37 pm
Location: SouthEast Michigan

Re: Mini GM detector

Postby Bill Fain » Fri Dec 23, 2011 5:06 pm

Hi, Joe Jarski special today 15:39 @ 16,400 feet asl. Actually got one more dot than this. Surprisingly strong for such a low altitude and small detector tube. I Suppose the TSA 470B (Henny Penny) would have gone crazy. Merry Christmas to all. -bill
IMG-20111223-00672.jpg
User avatar
Bill Fain
 
Posts: 90
Joined: Sat Jul 17, 2010 10:23 am

Re: Mini GM detector

Postby Joe Jarski » Sat Dec 24, 2011 3:58 pm

Wow! That's a lot higher reading than I would've expected. You weren't flying in a fiestaware plane were you? ;) The readings look about the same.
User avatar
Joe Jarski
 
Posts: 231
Joined: Thu Sep 16, 2010 8:37 pm
Location: SouthEast Michigan

Re: Mini GM detector

Postby Bill Fain » Sat Dec 24, 2011 4:08 pm

Hi, No, but I was about 10 miles from a nuclear fuel plant and 20 miles from that 10 Billion Dollar uranium deposit; although I don't think that would make any difference. -bill
User avatar
Bill Fain
 
Posts: 90
Joined: Sat Jul 17, 2010 10:23 am

Re: Mini GM detector

Postby Doug Coulter » Mon Dec 26, 2011 9:29 pm

Yes, but were you also zero inches from a hot source taped to the back? Bring that thing over next time, Bill - and lets see how it reacts to local sources and try to see how hot that really was (cross calibrate it)....that looks pretty hot from the time I saw that before - really took some stuff to get it going like that. Torbermite only got a couple more leds.
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
User avatar
Doug Coulter
 
Posts: 3515
Joined: Wed Jul 14, 2010 7:05 pm
Location: Floyd county, VA, USA

Re: Mini GM detector

Postby Bill Fain » Tue Dec 27, 2011 10:40 am

Hi, You know I wouldn’t knowingly fudge anything; heck I’m just happy when I get the results I’m supposed to get. I will calibrate it against a known (hot) source we both have ;(radium dial oil pressure gauge) and see what it says. Does make me wonder why it read so high though. Next flight I will take it and the Prm470B with me. Thought about taking the Ludlum and the Geo210, but I need a Geo 310 for that altitude.
Maybe we need a new thread for this like “High altitude induced Geiger counter anomalies”. I am wondering what influence the following things (if any) might have on it:
Reduced pressure on the Geiger tube. Cosmic scattering based on “N” inches of aluminum and other materials. Cosmic scattering within the geiger tube itself Radiation induced electronic issues.
Additionally are there any resources that detail current cosmic radiation intensity by altitude/geo-location. Did find this, but haven’t sifted through it yet. http://www.nasa.gov/mission_pages/sunea ... ex.html#q4
If nothing but satellite cosmic data exists; Maybe NASA could outfit airliners that routinely make the 39-40K Ft. trek across the country, with a “Standard Counter” . They could then piece the data together in a “Microsoft Synth” like way and create detailed cosmic ray data maps. These could then be compared to the Solar ejections that occurred from the sun and see what effect they have. You could of course see what you pick up from ground based stations, but you wouldn’t have the abundance of geo-location data. Also, ground based stations, would be more subject to humidity, cloud cover, pollution etc. , but are the final authority for “real world” consequences of solar and cosmic induced damage.
BTW, we got just every-now-and-then "blinks" (just like on the surface), below 6000ft. -bill
User avatar
Bill Fain
 
Posts: 90
Joined: Sat Jul 17, 2010 10:23 am


Return to Altoids tech

Who is online

Users browsing this forum: No registered users and 3 guests