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Author Topic: Radiation Counter  (Read 17715 times)
DaddyB
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« on: October 17, 2009, 01:36:23 AM »

I had an email from Brandi today asking two questions I couldn't answer. 1. What was the temperature at 100k feet?  I gave her what I had read and that was about -50C.  I thinks Larry's Wx station will answer that next year.
Question #2 was, what was the Radiation at 100k ft?  I had no answer for that either.  However...........
I was reading in some of the literature and saw where you could purchase a Geiger Counter ($149) from Aware Electronics, Model RM-60.  It is a small device that runs off a serial port connection, (5v).  I think all we would have to do is build a counter that could record the counts per period of time, and then transmit it to the ground or store the data on eeprom, or both.  The output is a 5v pulse.

Do y'all think this is a viable experiment?  If so, I will start getting the parts together.  Maybe we could include this in some of the telemetry.   Huh
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Dan
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« Reply #1 on: October 17, 2009, 05:25:37 PM »

I think it's a great experiment...I think that would give a bigger picture of what the outside environment is like along with Larry's weather data...I'll start trolling for cheaper components..hahah 
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Larry
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« Reply #2 on: October 18, 2009, 02:10:36 PM »

The Geiger Counter sounds like a good idea.  Sorry for laying low lately.  I have been busy and then this whole weekend I've been sick.

Anyway, I have been reading and keeping up with what is going on. 
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DaddyB
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« Reply #3 on: November 06, 2009, 05:56:34 AM »

I have the Pic side of the Geiger Counter working now.  Tongue  It took me a while to work out how the Timer-Counter works and then it took some more time to learn how to put Hi-Byte and Lo-Byte into one variable.  But I think I have that working now.
I made it count over 2200 counts during 30 seconds.  Tomorrow, I will set it for 60 seconds and see just how high I can get it to count.  Right now, it is set to count for 30 seconds and then display the results.  I have an LED that blinks (50ms) each second just to let me know it is working (I have to be able to see something going on! )  So now, I think I am ready to order the Geiger Counter Module.
I can post a copy of the code but I wasn't sure just how to do that.

« Last Edit: November 06, 2009, 06:00:31 AM by DaddyB » Logged
Larry
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« Reply #4 on: November 06, 2009, 01:09:04 PM »

Glad to hear you got it going.  About how many counts do you expect to get per minute or per 30 seconds?
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DaddyB
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« Reply #5 on: November 07, 2009, 05:29:58 AM »

Ok, I think it is about finished.  It will count Geigers  Grin and it will read the battery voltage.
the output format is:

          "GM,nnnnn,BT,nnn"    That is 15 characters.  If needed, I can cut out the 'M' and 'T' for two or remove the letters altogether.  There is one problem I can see.  Since my program doesn't know when its going to be polled, it may be in the middle of a count when polled.  It could store the info in the eprom and read it out when called.  Again, it may miss some of the cycles.  I could include a counter field that would increment by 1 each cycle.  Then we would know if it had been missed and how many.  I don't see it being that significant missing a few cycles.  We are comparing the count with altitude and I think it could be easily interpolated if need be.  In fact, I think I will add a cycle counter, if we have the room.  For a mission, it shouldn't go into more that 4 digits.
Larry, I think you said something about a 2 min window.  If we have a 2 min window, then there should be no problem.  As soon as the counter transmits, your program can move on to another read.  ( I'm just brain storming here).
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Dan
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« Reply #6 on: November 07, 2009, 06:27:08 PM »

Just thinking and throwing out ideas...Since you're only dealing with increments by one, you could do a binary count...That way you'd only use up 2 bytes counting all the way up to 65,535...3 bytes would push you up to 16M...You could let the processor on the ground sort out the Human Interface stuff (converting FFFF to a readable 65,535)...you'd have to do some testing to see how the RS-232 interface handles digital, but some of the APRS formats are binary so it must be doable...That way you can cram a whole lot more info on the data stream and you wouldn't have to worry about the 80 character limit on the TinyPack (if you're still planning to use that)...
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DaddyB
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« Reply #7 on: November 08, 2009, 04:29:45 AM »

The GM Reader/Controller has a few more things added (up to Ver 3.0 now).
The data string has a string counter now and also a polling input(will read a 5 volt pulse).  The counter will count data pulses from the Geiger Counter for 10secs or 30secs(or whatever we need).  Then stops the counter, and waits for the polling pulse. When it sees the Poll, it dumps the string count, the radiation count, and battery voltage into RS232 and resumes counting.

I will probably delete the string counter since we can track the order by GPS time.
Next week, will start building the 'beast' and get it off of the bread board.  The bread board caused me a lot of grief today with loose connections, etc.  Embarrassed
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DaddyB
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« Reply #8 on: November 10, 2009, 05:22:55 PM »

The Geiger Counter has been ordered.
Delivery will be 1 to 2 weeks.
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DaddyB
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« Reply #9 on: December 08, 2009, 01:57:22 AM »

Delivery was a little longer than stated but it arrived today.  Am checking it out with it hooked to the PC but soon will be wiring the cable to have it work with the PIC.  Background radiation levels here in my computer room are very low (thankfully!!) about 1 to 3 counts every 5 seconds.

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Dan
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« Reply #10 on: December 08, 2009, 02:27:58 AM »

Now comes the fun part!!  Grin
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DaddyB
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« Reply #11 on: December 08, 2009, 04:02:00 AM »

Right, no more excuses!!    Undecided
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DaddyB
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« Reply #12 on: December 09, 2009, 03:46:00 AM »

It works!! Cheesy  The PIC is counting!!

Sitting on the table here I get from 0 to 6 or 7 counts per 10 second period which translates to about 30 to 40 counts per minute, as a background count.
I need a small radiation source to test the equipment.

Next, get off the breadboard into a wired circuit....    Tongue
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Larry
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« Reply #13 on: December 09, 2009, 11:17:18 PM »

You could stick it in the microwave and see what happens.... Wink
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Dan
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« Reply #14 on: December 10, 2009, 12:51:02 AM »

Silly Wabbit! You'd have to stick it in a "micro-particle" for it to show on a geiger counter..hahahah
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