This includes an original hand painted twenty first century Jan Pantelje diagram. The original will be worth a zillion US dollars in the next century, considering art and inflation. I am willing to sell the original for 1000 $.
With that out of the way, now there is a big NATO meeting where I think they are drawing straws who may first use the bomb, some personal security is a good thing to have.
The circuit uses a PIC to count time, count pulses from a Geiger Mueller tube, and display this on an LCD, for now, just as counts per minute. There is also an audible click, made from an old cellphone piezo, and a blue flashing LED for each pulse. The PWM PIC output is used to make +500 V, stabilised by a bang bang ? feedback using one of the PIC comparators. The other PIC comparator does the pulse input from the GM tube. I am using an old tube from a surplus bomb eeeeh, radiativity detector, It is 1 R/h tube, and very insensitive, nevertheless it shows about 9 counts per minute. I have ordered some urad^Hnium so I can calibriate the high ranges. This is just a Saturday afternoon play, so no software release yet. The idea is to run it all from a 9 V battery, so far I measure 19 mA for the whole thing! (no LCD backlight used). On a 250 mA/h rechargeable it should last a day at least. The potcore in the picture is from same old army equipment, turns ratio 1:14.
I want to add some more soft to be able to accumulate counts etc, and accommodate a 10x more sensitive tube. The tube should eventually go in the box if I can make it fit. It also needs a small on/off switch, all parts came from the junkbox so far, but no such small switch in there.
Anyways, fun project, also a good cosmic ray detector I think.
I wonder if there is there an international standard for the battery symbol? Here (in the US) it is traditional that the positive terminal has the longer line in the symbol. I have noticed that this does not seem to be a global standard.
You have my highest compliments to include such excellent documentation in all of your work - pictures and schematic diagrams (higher contrast on the schematic would be easier on my tired eyes!)!!
On a sunny day (Sat, 20 Nov 2010 07:55:04 -0800 (PST)) it happened tomcee wrote in :
Hey, that could be my fault. I see LTspice does it the other way around. On the old 4.5V flat batteries the longer terminal was the '-'. Maybe that is why I used the longer line for the '-'.
On a sunny day (Sat, 20 Nov 2010 10:07:56 -0600) it happened Vladimir Vassilevsky wrote in :
diagram.
Interesting, does it have a diagram? I have some trouble with the language, every link seems to lead to GPL license.
Tell you what, I have an old radiation meter from 1962, it uses 2 ionisation chambers, and runs on a 1.5 V monocell. It uses a 1.5 V double triode, but for radiation detection it uses NO CURRENT at all. It just charges that chamber, and uses a metal vane that will eventually make contact if the charge dissipates because of ionising radiation. It also has a C14 calibration source in it, and I payed 10 Euro for it. On top of that it has a calibration report from the nineties sticker on it somewhere. Here a picture of it: ftp://panteltje.com/pub/stralenspurgerat_TTL6109A_img_2420.jpg Oldies but goldies:-)
No problem. I can get hand-painted schematic replicas made in Dongguan by University-educated art students for only 5 EUR each.
Best regards, Spehro Pefhany
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Oh no. For that you are too wealthy (not hungry enough) and you'll have to wade through a lot more of other misery. Maybe cutting a piece of your nose helps. (The ear have been done already so that one 's invalid.)
Yes, like a weather station that tells you when it's raining.
There are crystal based radiation exposure meters that use no electronics at all. The elecronics is needed only to read out the data and to reset back to zero. The life time is virtually infinite and the dynamic range is over 1e6.
On a sunny day (Sat, 20 Nov 2010 17:07:28 -0600) it happened Vladimir Vassilevsky wrote in :
Interesting, this was my first idea for the HV generator, to use the PIC PWM output at 50 % and then directly drive a transformer. I see they use a 4x voltage multiplier, and use the GM tube 'upside down'. But I already had the potcore, and the original circuit it came out is a few kHz blocking oscillator with a OC76 (Ge transistor), and 2 x multiplier. Did not want to wind a new coil, so I used that, and shorter PWM duty cycle. I did not really go for low current consumption, as I normally will use it on the desk, the 9 V battery can be connected via a diode as fall-back, it now has a real clock too, and displays the battery voltage. The PIC runs on 5 V from a 78L05, that one in itself is responsible for HALF the current (about 7 mA). LCD takes about 2mA, a few mA for the RS232 resistors, the rest is for the HV generator, and LED if on (10mA). I measured it without RS232 connected last night, and measured about 11.5 mA. When using something else than a 75L05 that leaves about 5 mA for the whole thing, makes 50 hours on a 250 mA/h 9V block. I had it running all night and logging to the PC via RS232. It is a nice thing on the desktop, the blue flashing light... I thought it would be distracting but it is not. Sort of an radioactive alarm clock :-) At 5 mA, at least theoretically, I SHOULD be able to power it from the RS232 DTR line, and do the LCD backlight from an other RS232 control line :-) Replace the 78L05 with a zener, but it would have to be very precise zener (or parallel stabiliser chip).
Nice pictures, yes this is a much longer GM tube, won't fit in my little box. Maybe I will leave the external probe, it is handy to check the food after the bombs fall.
Yes, the gel bases neutron detectors come to mind.
Here is last night's log, from: nice -n 19 ptlrc -d /dev/ttyUSB0 -b 19200 | grep --line-buffered cpm >
If I run sort on it, to find the unique values, I get: grml: ~ # sort -u radiation.txt cpm0 cpm1 cpm10 cpm11 cpm12 cpm13 cpm14 cpm15 cpm16 cpm17 cpm2 cpm3 cpm4 cpm5 cpm6 cpm7 cpm8 cpm9
So the maximum count was 17 per minute, and the minimum count was zero per minute. The PIC also sends a character on every tick via RS232, so all math and logging is possible.
On a sunny day (Sun, 21 Nov 2010 09:05:54 -0600) it happened "amdx" wrote in : .
The LED is on for a few milliseconds at every click (flashes). It will only draw significant current if more then a few hundred pulses / second happen. If that is the case, you will have a much bigger problem than a fast discharging battery :-).
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