A PIC based Geiger Muelller counter

9 counts/minute, RUN AWAY!

Here is the first 100 to get you started

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Nial.

He can't because he's going to be famous with this illegible handdrawn papers :)

petrus bitbyter

I have added the 0.1 version asm source code, released under the GPL: ftp://panteltje.com/pub/gm_pic/gm_0.1.ASM This code was assembled with gpasm-0.13.7 beta and I would not be a bit surprized if it did not assemble on MPlab.

Some comments on the code: I added micro Sievert display on line 2 of the LCD, this is derived from the counts per minute on line 1 by simply dividing by 100. That division factor is different for each type of GM tube, it is a #define at the top of the source file.

Measurement is once per minute, and this means you have to wait one minute for the first displayed value. If you have a more sensitive tube modify the code.

There is some interesting info on radiation exposure at the to of the asm file too.

I want to point out again, considering diagrams and code, that this is a design group, and if you are too stupid to get the gist from the sketches, or need hand holding to write code, try sci.electronics.basics, or oder a kit from somewhere, and complain to your mama. This is just about solutions and ideas. Things constantly change anyways, both in the hardware and the software.

As far as connectivity goes, this thing communicates with the PC at 19200 Bd, 1 start bit 8 data bits, 1 stop bit, no parity, if you are lucky. That last thing because it assumes your RS232 takes 0V for 0, and does not need at least -3V. If that sucks use a MAX232, or one of the many other solutions. You can type 'h' for a menu: grml: ~ # ptlrc -d /dev/ttyUSB0 -b 19200 Panteltje ptlrc-0.6 using device /dev/ttyUSB0 Escape exits. RS232 commands: B LCD backlight on, saved in EEPROM. b LCD backlight off, saved in EEPROM. C flash clock separator, status saved in EEPROM. c do not flash clock separator, status saved in EEPROM. D enters debug mode, continuously prints ADC steps for U GM tube, U battery, and flags2. d exits debug mode. F sets PWM frequency in kHz, range 19 kHz to 154 kHz, default 39 kHz, saved in EEPROM. GnnnENTER sets clock calibration, timer1 reload low byte, use 175 for nominal, is saved in EEPROM. at first power up (directly after programming) the EEPROM is set with the default value for G(175). HnnENTER sets hour, range 0-24. h prints help. MnnENTER sets minute, range 0-59. PnnnENTER sets maximum PWM value, range 0 to 100, stored in EEPROM. S sets soft start speed, range 1-15. s prints status: time, local/remote voltage control, max. pwm, pwm, battery voltage, GM tube voltage. UnnnENTER selects output voltage, range 0-31, stored in EEPROM. v prints version number.

As the attentive reader can see, you can set and get almost any parameter via RS232, you can set the GM tube voltage, the soft start, the max PWM width, the clock, look at the ADC values, look at the battery voltage, even control the LCD backlight. In this (new) diagram the LCD backlight is driven from a PIC pin and draws about

7 to 8 mA when on, just enough light to clearly see it in absolute dark, in even a slight nucleus [!G.W.Bush] sunshine you will need no backlight, possibly never again. Option F for PWM frequency depends on the kind of transformer you will wind (you will have to know how to do that) or use. You will have to set, without GM tube connected, the GM voltage to about 600 V with max PWM command P, and then set the voltage to normal with U7ENTER, that should show about 475 V. Do not play with U8ENTER or higher wit ha GM tube connected, this thing will go way above 500V. Here is my status display, all values are saved in EEPROM, at least in this value of the soft, and it should start up correctly with MY transformer, but not yours:

grml: # ptlrc -d /dev/ttyUSB0 -b 19200 Panteltje ptlrc-0.6 using device /dev/ttyUSB0 Escape exits.

Clock cal 175

0:27 PWM frequency 19 kHz PR2 reload 101 Softstart speed 10 Remote voltage control Uout select 7 PWMmax. 30 PWM 30 Ubat 10.2 V UGM 475 V

PS the battery shows 10.2 it is the maximum the display will go to, as normally it expects a 9V battery, but I am stuffing 12V DC into it to save buying or charging batteries.

LOL :-)

I know you have discussed the hard to see schematics as our problem. A couple of simple changes would be a great service to mankind. Don't you want to be known as someone that did a great service to mankind? MikeK

second happen.

discharging battery :-).

Try an old radium painted WWII cockpit instrument or wristwatch if you want a shock. They are good for a few kHz or so at close range. Rare earth cerium oxide polishing compound is about as radioactive as anything modern is allowed to be (traces of thorium in it). Dodgy quality gypsum and flyash breezeblock are other slightly hot things.

Regards, Martin Brown

"amdx" schreef in bericht news:865f1$4cebb528$18ec6dd7$ snipped-for-privacy@KNOLOGY.NET...

I considered so and did some experiments using an old version of Paintshop Pro. Readability can be increased considerably this way but much of the fun gets lost :)

petrus bitbyter

On a sunny day (Tue, 23 Nov 2010 12:57:13 +0000) it happened Martin Brown wrote in :

second happen.

discharging battery :-).

Yep, I ordered some of this:

and this:

In my youth we had a lot of uranium glass at home... And radium light switches were common too.

I just wonder, but will let you know if it arrives.... I finished the 'accumulated dose' software part, it is testing now, a 32 bits counter for the 'ticks', saved in EEPROM each minute, ticks / 10^6 is R with this GM tube. The mil unit I have: ftp://panteltje.com/pub/stralenspurgerat_TTL6109A_img_2420.jpg has a dosis counter that goes to 999 R, you'd be dead 99 times, wonder what they were thinking.

There exists uranium glass with 20% uranium.

Well it arrived 2 days ago, and I had a look. The 'radium' it contains is not present in any meaningful amount. The 'radium' package contained 2 watch hands, those register 2.7 x background up close (27 cmp on my meter versus about 10 for background). I also tested both samples on my antique big after the bomb meter, same result or less. A simple double test, I waited until late at night, and checked if those watch hands were visible, no way could I see them even with dark adapted eyes. They light up in absolute darkness for a few seconds (maybe 6 seconds) after you shine a powerful flashlight on it. So probably just ZnS (zinc sulfide), maybe a painted over old watch, or kept next to other real radium watch hands. This also makes me wonder about the cleanness of the senders operations, does he even have and use a GM counter? As radium has a half life of 1601 years, it should still work if any was there... I still am thinking of how to send the message to 'seller' in a political way.

As to the 'uranium' sample, in the form of uranium glass, that shows absolutely no increase in radiation. Looks just like coloured glass to me. The claim 'it lights up under UV light' does not mean the glass contains any uranium, even a bottle of London Tonic (quinine) lights up under UV light... We have discussed and tried that here some years ago.

The reason I wrote 'I wonder' in my original posting is that, with all those detectors everywhere, and this going by ship from the UK to the Netherlands, I was fully expecting to get a message that it was intercepted because of 'radiation'. Well this sort of radiation is really undetectable from more then a centimetre away,

Not a recommended ebay seller for radioactive elements, but the did send a few free lead samples... LOL.

Radium, on watches, or instrument dials, lights up very brightly even in full daylight, and of course it stays bright in the dark...

Maybe I will have to build that fusor after all, to get some neutron flux:-) That experiment has been on the backburner for at least 10 years.

Last time i looked 'fusor' was a factor 1 00 000 below break even, but real fusion.

Interesting stuff, next:

And a pile of 20% uranium glass with copper water pipes through it, a heat exchanger and steam turbine wont work either to bring electricity costs down. But real uranium will, but then probably somebody would object, you need lead screening too, LEAD is dangerous.

LOL

up close (27 cmp on my meter versus about 10 for background).

Easy test if you have a microscope is put them under good focus and then switch out the lights and wait 15 minutes. If it is a radium (or tritium) powered scintillator then the light doesn't fade and on a good day you can see some of the flashes from alpha particles. My fathers radium dial wrist watch would set off radiation alarms at close range.

or less.

hands were visible, no way could I see them even with dark adapted eyes.

you shine a powerful flashlight on it.

next to other real radium watch hands.

he even have and use a GM counter?

there...

Your best bet is an old junk shop or car boot sale and sharp eyes.

absolutely no increase in radiation.

Natural uranium isn't really all that radioactive (depleted even less so provided it hasn't been through a fuel cycle). But if it is uranium glass it fluoresces strongly green in UV and looks golden yellow in natural light with a tinge of green if there is longwave UV about. It is by far the most common fluorescing glass. There are other mixes that give primrose yellow without using uranium (phased out post WWII).

I have handled a chunk of Trinitrite - it also was disappointingly non radioactive and green glass more from iron impurity. The stuff was used for jewelry at one point which was singularly ill advised.

Fallout threat decays by roughly 10x for every 7x increase in time.

uranium, even a bottle of London Tonic (quinine) lights up under UV light...

detectors everywhere,

to get a message that it was intercepted because of 'radiation'.

away,

Even if it was radium most of the alpha particles would be stopped by a single sheet of paper so that isn't too surprising. The betas go a bit further and the gammas are not easily stopped. You might want to try geological/mineral specimen vendors it should not be too hard to get a small piece of pitchblende or other uranium ore (don't breathe the dust). Lab reagents tend to be somewhat depleted in U235 just as lithium tends to be short on the fusable Li6 isotope.

free lead samples... LOL.

daylight,

That is the main reason it was used - self powered. Shame about the effects on the unfortunate girls who painted the dials though.

exchanger and steam turbine wont work either to bring electricity costs down.

screening too,

Amazingly depleted uranium encased in pre nuclear age steel is sometimes used for screening sensitive experiments. The combination packs the most screening in the smallest physical space. Depleted uranium is used in some surprising civil applications...

Regards, Martin Brown

AIUI, they licked their brushes to bring them to a fine point!

--
"For a successful technology, reality must take precedence 
over public relations, for nature cannot be fooled."
                                       (Richard Feynman)

On a sunny day (Mon, 29 Nov 2010 10:17:31 -0800) it happened Fred Abse wrote in :

Makes you wonder if radium tastes good :-)

That is the story I was told. A lot of them worked for Smith Industries.

I dunno. The world record for human consumption of the stuff was held by the unfortunate Mr Eben Byers who consumed about 3x lethal dose of Radithor. Buried in a lead lined casket to protect the mourners.

Regards, Martin Brown

On a sunny day (Mon, 29 Nov 2010 20:58:39 +0000) it happened Martin Brown wrote in :

Yes, I have read that story. I think if radium tasted bad, they would not have licked their brushes. Perhaps the evirowhiner solution would be to add something to radium so it does not taste so good ;-)

Panteltje Atomics We Glow Green

Are you sure? If it is in a matrix, the actual mass itself is likely closer to equal.

diagram.

somewhere.

The sticker in the upper right corner of that box is NOT "from the '90s.". The sticker itself uses '60s technology for affixation (lacquer over label), which hasn't been used in SEVERAL decades (even over there... sorry). And there is no arguing, because it is obvious. The "995" is the calibrator's 'number'. And the lacquer is aged beyond 'the nineties'.

All the detectors I have dealt with required an HV excitation potential be generated for the transducer probe. Don't know about that foreign shtuff.

they were thinking.

Many of the folks that used the meters were in suits, you big dope.