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atomic.dave
USA
65 Posts |
 Posted - 09/08/2011 : 07:32:15
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| I was wondering if anyone has gotten readings over 3000 on their 080? I installed a LND712 which has read up to 108000 cpm from a AM241 pellet placed on the mica window while using a different Geiger counter. But on the 080 and outputing data to Geigerbot I only see 3000 max. Same with an LND7616- only 3000 max. Does the 080 have counting limitations? |
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| Reply #1
atomic.dave
USA
65 Posts |
Posted - 09/11/2011 : 10:03:05
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I wonder why no one has replied to this post? ZLM, any comments on this subject, cause it is kind of a major issue don't you think? Aren't any of the other user's interested in this, or are you satisfied with a max reading of 3000? is this counter only a low to mid level counter? if so then ok, but I would like to know the answer to this.
quote:
Originally posted by atomic.dave
I was wondering if anyone has gotten readings over 3000 on their 080? I installed a LND712 which has read up to 108000 cpm from a AM241 pellet placed on the mica window while using a different Geiger counter. But on the 080 and outputing data to Geigerbot I only see 3000 max. Same with an LND7616- only 3000 max. Does the 080 have counting limitations?
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| Reply #2
Odiez1
73 Posts |
Posted - 09/11/2011 : 11:19:16
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I'm silent cause I have no ideas on this one.. You need the expert.
I think the way of measuring the cpm, relying on a computer soundcard for A-D (analog to digital) conversion leaves a lot of room for error with the types of chipsets used for soundcard these days sucking more and more.. They make em' smaller and cheaper than ever, keeping profits up, but quality the digital went down the tubes (partly for DRM purposes I believe..)
If there were a limitation to the CPM I think it would be on the computer side of the counting method. I mean the Am241 was just screaming on the GMC and only 1290 cpm in the software? It should have been 100k cpm... And the GMC sounded like it was ~100k CPM...
Just a theory tho..
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-Odie |
Edited by - Odiez1 on 09/13/2011 12:38:18 |
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| Reply #3
ZLM
1261 Posts |
Posted - 09/13/2011 : 10:03:05
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| That is the comnputer and software issue. The software will take longer time to process and log the count if the computer speed is slow. |
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| Reply #4
atomic.dave
USA
65 Posts |
Posted - 09/13/2011 : 11:31:34
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ZLM: are you saying that the GMC080 is capable of counting up to and more than 100k for a sample such as AM241? I am talking with the Geiger Bot guy to find out what he knows about this issue. To be continued.
quote:
Originally posted by ZLM
That is the comnputer and software issue. The software will take longer time to process and log the count if the computer speed is slow.
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| Reply #5
Odiez1
73 Posts |
Posted - 09/13/2011 : 12:53:08
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Here's more info on A-D conversion..
en.wikipedia.org wiki Analog-to-digital_converter
_____________/____/___
How come we can't have a / next to an "a"? Anyways...
It shows that the ADC as they call it, is critical for this working properly. Has anyone thought to record the "data" signal sound yet? Let's see what it looks like in Audacity..
If you have a cheep Crystal Sound Fusion or Realtek then I bet the counts won't be as high as if you used a professional Digigram card. The old ISA Soundblasters were better than today's Crystal Sound and Realtek, even the super surround-sound Soundblasters of today..
Also when using USB and FireWire soundcards, you introduce an element of delay which DEFIANTLY will effect the CPM counts.
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-Odie |
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| Reply #6
Odiez1
73 Posts |
Posted - 09/13/2011 : 13:04:24
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Another page talking about the soundcards for home studio use.
www.homerecording.com/sound_card_basics.html
He specifies what to do with the microphone input as, "nothing". He suggests to use a mic preamp, and go line level signal into the computer. It sounds strange I'm sure.. But the software doesn't care what input the signal is coming in on, you have to use the Windows Mixer to choose the right one anyway. So maybe the soundcard is creating distortion and missing the counts?
I must say my 1290CPM was through my Lenovo laptop with has a sucky internal soundcard and NO LINE IN.
I may use one of the production computers at my work to test my theory about distortion, and using a preamp.
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-Odie |
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| Reply #7
Odiez1
73 Posts |
Posted - 09/13/2011 : 15:11:13
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Hey Atomic.Dave, is this your work on this DIY site?
https://sites.google.com/site/diygeigercounter/gallery
I referenced that site for a different page, and found some pictures which look like your Lego Geiger counter. You never said you made a combo probe with the SBM-20 and the LND-712.
That's cool! You've been at this a bit longer than I have it seems..
How does the GMC-080 compare with the other "kits" you've worked with? |
-Odie |
Edited by - Odiez1 on 09/13/2011 15:11:36 |
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| Reply #8
atomic.dave
USA
65 Posts |
Posted - 09/14/2011 : 09:16:51
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haa. Good detective work.
Yes, that is me. Yes, actually this is my third "kit" the first was a chaney C6981 with digital display. It has the SBM-20. It works pretty good, but many people were having issues with it although I did not. But I wanted to get the data on my computer for graphing.
Thats when I got the Brohogan kit that I found doing some googling. The designer John G is an awesome tech support and he guided me gently thru the build process explaining everything step by step. It has an LCD display and FTDI/usb link for my mac. I am using Arduino for programming and for the data upload. But it is a little bulky and without a case. Also, I wanted to be able to plot data on my iphone too for mobile applications.
Thats when I got the GQ kit. I like it for size and portability. The data output too was nice to hook up to Geiger Bot and my iphone. I am still fumbling through the settings though and not even sure how accurate it is. The brohogan kit is very accurate I believe. There is a guy online that ustreams his Inspector live and its kinda funny cause he's in West LA, and I am in East LA, and when his number is at a certain amount, a moment later so is mine. Like the brohogan is capturing the same.
I currently have a russian CI-180G (awesome tube at 15 ebay) large metal tube with it, and it is pulling pretty high background rad. I used to have the LND712 and the SMB20 in parallel in that probe, but i had grounding issues with it and/or the cable, so I took it apart and have just the board and tube just laying on my desk for now.
But Yes, I have been at it for a little while, but like I said before I don't really know components very well, I am just a really good assembler, and follow directions well if they are clear.
PS> I have the parts on order to upgrade the 080 for the 7616 (the caps were backordered). But still I am not sure if that will fix the maxing of counted data at 3-5k. The Geiger Bot guy told me a trick to get it to count faster, and it increased it from 3-5k, but that is not even close to the 108K my brohogan kit counts with the LND712. Is 1900 still your highest count with your 6107 and modded 080? doesn't seem right...
PSS> I spoke with the GQ guys, and they are in the process of making the right data cable for iphone hookup. I have modded one for me, and was researching having it made in China, and found a source, but after finding out GQ was doing it, decided to ditch it.
quote:
Originally posted by Odiez1
Hey Atomic.Dave, is this your work on this DIY site?
https://sites.google.com/site/diygeigercounter/gallery
I referenced that site for a different page, and found some pictures which look like your Lego Geiger counter. You never said you made a combo probe with the SBM-20 and the LND-712.
That's cool! You've been at this a bit longer than I have it seems..
How does the GMC-080 compare with the other "kits" you've worked with?
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| Reply #9
hellbet
France
13 Posts |
Posted - 09/15/2011 : 07:27:48
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I got up to 10.000 CPM just by letting my G/M tube facing the sun, box opened. I'm using GMC200 with the "suncatcher" GMT02 tube and third-party software though.
Do I win something?
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| Reply #10
ZLM
1261 Posts |
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| Reply #11
Odiez1
73 Posts |
Posted - 09/15/2011 : 10:45:04
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That's a really competitive price!
I bet snApple would charge 50$ for the identical thing, except it would be white colored and gold plated..
Hey Hellbet, can you say what kind of computer and soundcard you're using with the GMC200? For a Windows machine, open the Volume Mixer, then click the Options Menu, the Properties there.
My work PC has a SoundMAX Digital in a Dell Optiplex. |
-Odie |
Edited by - Odiez1 on 09/15/2011 11:14:50 |
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| Reply #12
hellbet
France
13 Posts |
Posted - 09/16/2011 : 04:45:20
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@Odiez1: Puter is an old laptop Panasonic CF-T4 series (semi-rugged) and soundcard is a "Sigma-Tel C Audio"
Have a nice day,
jm |
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| Reply #13
Odiez1
73 Posts |
Posted - 09/24/2011 : 21:12:06
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I finally got over 3000!
After some weird computer problems I'm back up, with more pictures...
This was off of a smoke detector pellet with the CBON-6107 and the modified HV side and the C2 mod..
Here's my graph of the CPM, the peak was over 41000 CPM. I started out with it in a plastic bag up close to the window, then out of the bag from 2" away until it was right in the window.
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Here's the Mic volume setting. The "Boost" was off.
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And this is what it looked like going into the SoundMAX on my Lenovo laptop.
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I tried to adjust it so the peaks weren't quite hitting the clip point (Where the peak is outside the top or bottom of the graph). As you can see it dropped below the bottom of the graph, but that was "Screaming" off the source. This is called Negative Bias under load.
The "center" of the wave moved downwards, but it still worked well enough.
The threshold for the CDV software was at 100. I like to see 1 'pop' of the GMC080 equal 1 count on the counter, then let it rip fully.
I'm convinced there's something near working correctly after all.
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-Odie |
Edited by - Odiez1 on 09/24/2011 21:18:02 |
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Readings over 3000?
