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Using Arduino => General Electronics => Topic started by: flamturpolt on Jun 27, 2012, 05:58 am

Title: geiger tube schematic, help with components sourcing?
Post by: flamturpolt on Jun 27, 2012, 05:58 am
Hi, I recently found a cool schematic for a cheap Geiger counter. The schematic is fairly simple, but since I am new to this, I don't understand the labels they have put for the components. I copied all of labels for the parts and searched them, and I have found all of them (or at least I think so). If anybody could read the schematic and give me the parts list (if I have read it wrong), it would be greatly appreciated. :) 

Here is the link to the schematic:
http://madscientisthut.com/wordpress/wp-content/uploads/2011/03/Geiger_board.jpg
Title: Re: geiger tube schematic, help with components sourcing?
Post by: CrossRoads on Jun 27, 2012, 06:22 am
What have you located so far?
Title: Re: geiger tube schematic, help with components sourcing?
Post by: flamturpolt on Jun 27, 2012, 06:28 am
Everything in the schematic (except for the optional part). Although I could be wrong.
Title: Re: geiger tube schematic, help with components sourcing?
Post by: CrossRoads on Jun 27, 2012, 06:46 am
You can search at digikey.com for N-Channel Logic Level MOSFET, they are plentiful.

I'd be more worried about the 500V or whatever the high voltage is that drives the geiger counter.
Title: Re: geiger tube schematic, help with components sourcing?
Post by: MarkT on Jun 27, 2012, 11:54 am
The mosfet is a low power one, probably only need an amp or less Ids rating - its purpose is to provide an open-drain output signal.  I think an NPN (2n2222) transistor could be used to make an open-collector output instead (anyone see why not?).
Title: Re: geiger tube schematic, help with components sourcing?
Post by: Grumpy_Mike on Jun 27, 2012, 12:01 pm
Yes it would work.

However I think the OP is missing something. This is not a complete circuit of a Geiger counter because it misses out the circuit that supplies the HV_input. This stands for High Voltage input and depending on the tube is normally between 400 to 800 Volts. So the normal way to get this is to have an inverter circuit. In most GM (Geiger Muller) circuits this is the major part, the bit you have posted seems over complicated as all it does is to take the high voltage pulse from the GM tube and make a speaker click.
Title: Re: geiger tube schematic, help with components sourcing?
Post by: wanderson on Jun 27, 2012, 03:28 pm
Most of the geiger circuits I see, have a major failing, they do not provide any regulation for the high voltage power supply, which can contribute  multiple pulses being displayed for a single event, such as the Sparkfun circuit.

(http://www.sparkfun.com/tutorial/GeigerCounter/P1050665large.JPG)

Whereas, the proper waveform should look more like,

(http://eetimes.com/ContentEETimes/Images/Design/Prog%20Logic%20DL/2011-04/geiger-02.jpg)
Title: Re: geiger tube schematic, help with components sourcing?
Post by: flamturpolt on Jun 28, 2012, 01:20 am
I forgot to mention that I am acquiring the HV power supply from a disposable camera flash. I only need to know the resistors and capacitors. The left side of the schematic ( from resistor R8 down) is optional. I only need to know if the object I'm measuring is radioactive or not. (For radioactive antique hunting.)
Title: Re: geiger tube schematic, help with components sourcing?
Post by: Docedison on Jun 28, 2012, 01:27 am
There are 5 - 12V DC input devices to be purchased on the internet in the $40.00 - $60.00 range and it can be done for quite a bit less money. But as voltages of that level are generally fatal, a project like that is not for the less experienced. IMO

Doc
Title: Re: geiger tube schematic, help with components sourcing?
Post by: flamturpolt on Jun 28, 2012, 01:36 am
Disposable cameras are in the $5-$10 range. They would be cheaper.
Title: Re: geiger tube schematic, help with components sourcing?
Post by: Docedison on Jun 28, 2012, 01:46 am
Don't take really good pictures though...

Doc
Title: Re: geiger tube schematic, help with components sourcing?
Post by: flamturpolt on Jun 28, 2012, 02:18 am
:)
Title: Re: geiger tube schematic, help with components sourcing?
Post by: wanderson on Jun 28, 2012, 03:21 am
Camera flash supplies are rarely over 350v whereas most geiger tubes need ar least 400v and most are around 500v.

Cheap is possible but not likely achievable by someone without considerable experience.
Title: Re: geiger tube schematic, help with components sourcing?
Post by: flamturpolt on Jun 28, 2012, 03:30 am
The guy who made the schematic posted videos of it working. I am looking at a Geiger tube to buy that runs on that voltage. Can anyone tell me the parts list? :)
Title: Re: geiger tube schematic, help with components sourcing?
Post by: wanderson on Jun 28, 2012, 03:32 am
Geiger tubes that run on voltages that low only detect gamma...  something your not likely to encounter in antique objects..
Title: Re: geiger tube schematic, help with components sourcing?
Post by: flamturpolt on Jun 28, 2012, 03:36 am
The tube I found detects beta and gamma. Unfortunately no alpha :(. It'll do, though.
Title: Re: geiger tube schematic, help with components sourcing?
Post by: Docedison on Jun 28, 2012, 04:04 am
There is still the point that the OP seems a little inexperienced to be able to play with a flash or any other type of High Voltage supply regardless of it's source. With a great deal of care and knowledge one could put 2 in series and have a 700 - 800 V supply too. BUT NOT with disposable camera supplies as they are only good for 150 - 200 Vout, it's a little bitty tube, doesn't take much to ionize the gas, a 1Kv trigger and about 150 V for the flash. A GM tube is a big neon light... essentially. it measures high energy pulses by drawing enough current to cause the gas to ionize and a combination of the power supply and the gas composition and pressure quenches the ionization and the event is monitored by current sensed in the ground leg of the combination, If I remember what I studied about it in the books long ago... The whole thing using HV power supplies is just too dangerous. I would be nervous to even play with it in a fully equipped lab and I have worked with HV supplies all my life. Better to follow that Elektor photo-diode experiment and build it... Elektor even supplies a kit... of ALL parts.

Doc
Title: Re: geiger tube schematic, help with components sourcing?
Post by: wanderson on Jun 28, 2012, 04:09 am
Knowledge is obtained by those who survive. :)
Title: Re: geiger tube schematic, help with components sourcing?
Post by: Docedison on Jun 28, 2012, 04:30 am
Didn't Confucius say that... or was that the one about women flying... <BFG>

Doc
Title: Re: geiger tube schematic, help with components sourcing?
Post by: Grumpy_Mike on Jun 28, 2012, 06:09 am
I designed a simple geiger counter back in 86
The text is here:-
http://www.doc.mmu.ac.uk/STAFF/A.Wiseman/Acorn/BodyBuild/BB_86/BBC40.txt (http://www.doc.mmu.ac.uk/STAFF/A.Wiseman/Acorn/BodyBuild/BB_86/BBC40.txt)

And the schematic is attached. I used a 240V mains to 3V miniature transformer backwards to provide the HT. The input marked bit 7 is the input for the inverter and can be a PWM signal from the Arduino or a 555 timer. The output marked bit 6 is where the clicks occur.
Title: Re: geiger tube schematic, help with components sourcing?
Post by: flamturpolt on Jun 28, 2012, 03:27 pm
Is it portable?
Title: Re: geiger tube schematic, help with components sourcing?
Post by: Grumpy_Mike on Jun 28, 2012, 04:52 pm
Well it was designed to feed into a computer, but given a 12V supply, a 555 oscillator, and LED or phones on the output then yes.
Title: Re: geiger tube schematic, help with components sourcing?
Post by: flamturpolt on Jun 29, 2012, 02:26 am
Thanks, I will consider it.
Title: Re: geiger tube schematic, help with components sourcing?
Post by: flamturpolt on Jun 29, 2012, 03:36 am
I saw a resistor in the schematic that was labeled 4700k. Does this 4700k ohms? By the way, I found some radioactive fiesta-ware today. I also have a video about the fiesta-ware I found today, if anyone is interested.

http://www.youtube.com/watch?v=5kbdnYWxMnA
Title: Re: geiger tube schematic, help with components sourcing?
Post by: westfw on Jun 29, 2012, 07:58 am
Quote
Camera flash supplies are rarely over 350v whereas most geiger tubes need ar least 400v and most are around 500v.

If you follow the actual instructions, they do modify the flash.  The main cap is removed, and the unit is powered from 3V instead of the normal 1.5V, so it at least has potential to produce reasonable voltages.  I couldn't say how well the whole Geiger counter works, but it doesn't look completely bogus.  (I would have put a voltage doubler after the transformer instead.)

http://madscientisthut.com/wordpress/daily-blog/hacking-a-disposable-camera-flash-unit-to-power-a-geiger-tube/

What tube did you end up with?
Title: Re: geiger tube schematic, help with components sourcing?
Post by: Docedison on Jun 29, 2012, 08:08 am
Just proves that you can get stoopider by the day, I hadn't thought about it but now... Boosted B+ in OLD color sets was 'kinda' done that way and even before that... I remember a Zenith Transoceanic that did stack two 67 1/2 V batteries for the Audio stages I think... was one of the early versions with the Loctal tubes. All  tubes from 1949 or 50 I think. I never saw one until I learned to fix them in my early teens.

Doc
Title: Re: geiger tube schematic, help with components sourcing?
Post by: wanderson on Jun 29, 2012, 01:27 pm
Given that you are just looking to test fiestaware you may want to consider a spinthariscope rather than jury rigging your own geiger counter.  They don't need batteries, and provide a visual indication of radioactivity.  And they meet one other of your requirements--they are cheap.

http://unitednuclear.com/index.php?main_page=index&cPath=2_12 (http://unitednuclear.com/index.php?main_page=index&cPath=2_12)
Title: Re: geiger tube schematic, help with components sourcing?
Post by: Docedison on Jun 29, 2012, 06:52 pm
That among several other fluorescent materials is the emitter for a scintillometer, The detector was a Photo multiplier tube, an extremely sensitive photon amplifier, designed it the 1930's and widely manufactured in the 50's through the 90's when the tubes became scarce. Elektor ran a complete Photodiode particle detector recently and there have been at least 3 follow-up articles from other sources since...

Doc
Title: Re: geiger tube schematic, help with components sourcing?
Post by: wanderson on Jun 29, 2012, 09:04 pm

That among several other fluorescent materials is the emitter for a scintillometer, The detector was a Photo multiplier tube, an extremely sensitive photon amplifier, designed it the 1930's and widely manufactured in the 50's through the 90's when the tubes became scarce. Elektor ran a complete Photodiode particle detector recently and there have been at least 3 follow-up articles from other sources since...

Doc


The device I mentioned makes no use of a photo-multiplier tube or diode, it requires no power at all.  Simple and easy detection of radioactive materials;

"Way back in 1903, Sir William Crookes was experimenting with the most expensive material on Earth at the time... Radium Bromide.
Working in total darkness, he accidentally spilled a small quantity on a thin layer of a special type of activated Zinc Sulfide (ZnS). To make sure he recovered all of the expensive Radium Bromide, he used a magnifying lens to locate every single speck of it. To his amazement, he noticed flashes of light occurring around each tiny grain of the radioactive material. It was found that the flashes of light were caused by the individual Alpha particles emitted from the Radium compound, striking the activated Zinc Sulfide. The flashes of light were individual photons emitted from splitting atoms. " 

I know that you weren't saying this was scintillator, but I wanted to clarify for those less familiar with the subject.  :)  Indeed one can still purchase scintllator detectors, which can be much more sensitive than traditional geiger counters.
Title: Re: geiger tube schematic, help with components sourcing?
Post by: Docedison on Jun 29, 2012, 11:30 pm
I was referring to hacking... <BG> your device, I used them in both high school chemistry and physics classes, Even used one from a 'Foot Ex-ray" machine Geez If I knew then what I know now about that subject you wouldn't even gotten me to Dis-assemble it, let alone turn it into a class project, (personal). A Fluoroscope... We X-rayed almost everything... that would fit, even a really small 8th grade girl... I moved the 'Viewing Screen" down so the whole thing was at waist level, the students in wood shop made a nice box for it with a bracket to hold the 'Screen" and the Visor... I got an A for that class... Probably should have been drowned at birth... Might have been a safer world. I remember an X ray machine I made from a Scientific American "Amateur Scientist" Article... used an 01A tube (1920's triode tube) and some aluminum foil and instead of the spark coil HV Supply I used an old Color TV set... With the 6BK4 pulled (Shunt HV Regulator tube) I got about 40KV and made some great pictures until a neighbor who knew a little more than I did told my parents about the possibility of radiation burns.

Doc
Title: Re: geiger tube schematic, help with components sourcing?
Post by: wanderson on Jun 30, 2012, 12:38 am
I still have my X-Ray machine somewhere I built from the same Amateur Scientist column.  For mine I used a neon sign transformer from an earlier tesla coil...

I do miss the old Amateur Scientist column...
Title: Re: geiger tube schematic, help with components sourcing?
Post by: flamturpolt on Jun 30, 2012, 01:49 am

Given that you are just looking to test fiestaware you may want to consider a spinthariscope rather than jury rigging your own geiger counter.  They don't need batteries, and provide a visual indication of radioactivity.  And they meet one other of your requirements--they are cheap.

http://unitednuclear.com/index.php?main_page=index&cPath=2_12 (http://unitednuclear.com/index.php?main_page=index&cPath=2_12)


Well, a Spinthariscope needs total darkness for I think about ten minutes. Something that is not possible in an antique store.
Title: Re: geiger tube schematic, help with components sourcing?
Post by: Docedison on Jun 30, 2012, 06:30 am
No it's 10 minutes for your eyes to adjust...
I tried to buy the cd... of all the columns, had it once and loved it... there are 3 available through amazon across the US...@ $183.00 ea... Used only.

Doc
Title: Re: geiger tube schematic, help with components sourcing?
Post by: wanderson on Jun 30, 2012, 03:20 pm
For those prices you would be better off purchasing CL Stongs book.  Granted it doesn't contain the latter columns, but those weren't as good since they got watered down by the safety police...

http://www.amazon.com/gp/offer-listing/B000ICZI3Y/ref=dp_olp_0?ie=UTF8&condition=all (http://www.amazon.com/gp/offer-listing/B000ICZI3Y/ref=dp_olp_0?ie=UTF8&condition=all)
Title: Re: geiger tube schematic, help with components sourcing?
Post by: wanderson on Jun 30, 2012, 03:21 pm


Given that you are just looking to test fiestaware you may want to consider a spinthariscope rather than jury rigging your own geiger counter.  They don't need batteries, and provide a visual indication of radioactivity.  And they meet one other of your requirements--they are cheap.

http://unitednuclear.com/index.php?main_page=index&cPath=2_12 (http://unitednuclear.com/index.php?main_page=index&cPath=2_12)


Well, a Spinthariscope needs total darkness for I think about ten minutes. Something that is not possible in an antique store.


Not in my experience, I have used them indoors in daylight.  Granted the dark it is the better the show!
Title: Re: geiger tube schematic, help with components sourcing?
Post by: BulletMagnet83 on Jun 30, 2012, 04:12 pm
It's quite possible to get over 1kV (if you wanted to) out of a modified disposable camera flash circuit. I've done it myself and once you know how it's pretty easy to build the circuit from scratch. As you won't be discharging massive pulses from giant capacitors, there's pretty much no chance of you seriously hurting yourself anyway - you can grab the output wires and while it won't be very nice, it's not going to do you any real harm. The poor thing can't supply a lot of current anyway before the transistor gives up and dies.
Title: Re: geiger tube schematic, help with components sourcing?
Post by: wanderson on Jun 30, 2012, 05:44 pm

... there's pretty much no chance of you seriously hurting yourself anyway ...


While the odds of serious injury are relatively small, there is a reasonable and distinct possibility of serious (up to and including lethal) harm when working with such circuits.  Working with high voltage circuits deserve caution and most importantly a lot of reading before hand.  If someone doesn't understand how the circuit in question works, they are much more likely to hurt themselves.

I'm all for building stuff from scratch, if your primary goal is learning about how such things work; however, if the primary goal is to use the device it only makes financial sense if you have a fair bit of experience both in constructing circuits as well as in understanding how they work.  If you don't you will almost certainly spend more money (not even counting the time involved) getting a working device that even then will not perform as well as what you could have purchased...
Title: Re: geiger tube schematic, help with components sourcing?
Post by: BulletMagnet83 on Jun 30, 2012, 07:11 pm


While the odds of serious injury are relatively small, there is a reasonable and distinct possibility of serious (up to and including lethal) harm when working with such circuits.  Working with high voltage circuits deserve caution and most importantly a lot of reading before hand.  If someone doesn't understand how the circuit in question works, they are much more likely to hurt themselves.



Well I wouldn't ADVISE anyone grabs the HV output on purpose, of course! Just saying that it's not particularly dangerous compared to discharging a capacitor into yourself or coming into contact with live mains wiring. I'm sure we could all debate the relative dangers of these little HV inverters til we're blue in the face, but I think the absolute worst you'd get is a small burn. I'd compare it to a stinging, tingling sensation rather than a full-on electric shock, and I've had a fair few... I tend not to worry that much about tiny battery powered things if there's no beefy capacitors involved.

In my humble opinion the greatest danger of injury is indirect - jerking your hand away suddenly and hitting it against something hot or sharp. If you play with HV, sooner or later it's going to happen. You can minimise the risk with some PPE but it's all part of the learning process :D
Title: Re: geiger tube schematic, help with components sourcing?
Post by: flamturpolt on Jul 01, 2012, 04:13 am
I researched Elektor's photo-diode kit. It seems pretty cool. Has anyone ever bought this kit? It is in my price range.