Ion Chambers and Geiger

Comments and ideas for the measurement of Radon and radiation

Two SBM-20 in parallel and a GeigerAdapter form a simple probe, very sensitive and inexpensive.

This image shows a measure of environmental fund with Theremino_geiger

More information
– Software download:
– Electrical schematics and Assembly plans:
– Hardware, DIY and kits:
– Images and videos:
– Article about Open Source Electronics:

In the documentation folder (accessible from the Help menu) you will find all the information you need to use the program and probes.

The HAL program, required to connect to the Master, you download from here:

Measure with Geiger

This image shows a measure of environmental fund 15 minutes, followed by the provision of a sample of dietary salt. At the beginning of each measure was pressed “Start”

Precision measurements you make with long integration time. While precision measurements you do not have to change the conditions of measurement. Move the samples during the measurement would be like taking a fever without taking the thermometer in the same spot for the three minutes required.

All ’ start of the measurement You should press the button “Start new measure” that is how “Reset the thermometer” Before measuring a fever. Without this initial zero setting it is likely that the fever has not indicated its, but someone else.


To make precise measurements You must respect the agreements with the program, the instructions are explained, in detail, the procedures to be followed.

To make quick measurements, just set the “usual” 2 or 3 minutes of integration, using all portable geiger..


Some users would like to avoid having to follow the measurement protocol. In essence they would like a button “Start” you press alone, any significant variation of the radioactivity.

Early versions of Geiger had this option, but we found that this made the measurements unreliable and bore, in some cases, completely wrong measures, without being able to inform the user ’ and without any possibility of control by software. These errors were not due to an inaccurate implementation of ’ algorithm, but are inherent in the measurement method and any appliance that is automatically reset can avoid them.

As far as l ’ algorithm is sophisticated and set the trigger thresholds, There are always a few sequences of changes that lead to a zero delayed, resulting in pollution of the first part of the buffer of integration, or to a non-zero or, even worse, to reset drivers, they do lose hours of data.

To miss any appliance that resets by itself, proceed as per the following example:

1) Let it settle to the bottom

2) Bring a sample very radioactive 20 cm so that it resets and empty the buffer

3) Continue moving the sample up to contact, but very slowly, so as not to over take the reset threshold.

The first part of the buffer will be filled with samples too low, the threshold it clicks more and the measure will continue to be systematically flawed, How long you have the patience to wait.

This example sequence is extreme, but there are many real opportunities to attract more or less large errors, If you allow ’ user to move samples at any time, or add and remove fragments in a sample already to an extent.

The devices designed for measuring “on the field”, where it is important to react quickly, are not suited to precision measurements and can, in many situations, provide incorrect measurements.

Measure with the ion Chamber

Ion Chamber documentation files do not show enough that, in some cases, the pulse rate can be very low.

In environments with little radon (d ’ summer with wind and opened Windows) Radon concentrations may fall under the 0.1 PCI/l (4 Bq/m3). In these cases, you get even less than one pulse every 5 minutes. It can also happen to not measure no pulse for ten or fifteen minutes. The randomness then back to place the media, concentrating many impulses in 10 minutes after. The next image shows this behavior.

In this picture have gone well 9 minutes, before receiving the first impulse. In the central zone is also a period of 15 consecutive minutes without pulses.

That is why we designed a very large room (from 1 liter). With many commercial appliances impulses would also 100 times less frequent. For example a “Safety Syren Pro3” (a few cubic centimetres), would produce on average, Pulse every 7 hours and could spend long periods, even more than a day, no pulse.

Test of Thoron

If you live in an environment with little radon, the low frequency of impulses might suggest a malfunction of the room. Fortunately there is a Thoron, a similar Radon gas, but much more convenient for testing. More information about the test of Thoron, on pages 21 and 22 of the document “Radon_IonChamberElectronics”, download from here: /hardware/inputs/radioactivity-sensors

In the first part of this picture you see the Environment Fund. In the second part the mantle containing Thorium was positioned in the saucer, and been pressed Start. In the third part, the Start button was pressed again and in a few minutes the measurement has stabilised at about 5 PCI/l. In just over half an hour ’ l ’ error fell to 10%.

The gas mantles containing thorium are not all the same and the room may not fill completely due to leakage between the saucer and the room. Then the measured value may be different, Come on 5 PCI/l of this picture.

If you measure from 2 PCI/l to 10 PCI/l the test passed, Otherwise please email us.

In this picture the mantle with thorium and saucer were removed. L ’ indoor air was grossly cleaned up, waving a cardboard for a few seconds. Then the Chamber was lying horizontally, so leave the holes open to both terminals and pressed the Start button. In just over half an ’ now the room is completely cleaned up and returned to 0.1 PCI/l.

The ion Chamber should always be handled with delicacy. The bursts of pulses that are produced when the room is shaken, mild vibrations are produced by central wire and do not indicate a malfunction. Even dust bunnies can cause bursts of pulses, You may need to add dust filters. Read pages 25 and 26 of the document “Radon_IonChamberElectronics”, download from here: /hardware/inputs/radioactivity-sensors

  1. Paul says:

    Hello,putting the form geiger in an inner box and externally smb20 probe what cable should I use ? the maximum length between geiger and probe is 3 meters.

    Thank you

    • Livio says:

      Geiger Geiger tube Adapter and module must be together and together form the probe. The maximum distance between the GeigerAdapter and the Geiger tube is a few centimeters.

      Many projects that are on the network connecting the Geiger tubes with cables and connectors. Try, the pulses arrive, and they're happy as well. Even our GeigerAdapter work. But in doing so the Geiger tube must suffer and his life would be reduced.

      Parallel tubes manufacturers specify that there must be the minimum possible capacity. A cable, for example, three meters, It has a capacity from 300 AI 1000 pF. This ability is charged with 400 Volts, and you download onto the pipe at each pulse, generating very strong currents that “FRY” the pipe in a short time.

      Conclusions: Maximum 2 or 3 PF in parallel to tube. Up some centimetres of wire. Better to use unshielded wire. Better than the positive wire is as short, then turn the tube with the positive toward the Geiger Adapter.


      Attention: Geiger pipes outside wants a shed for the Sun, otherwise the container may exceed 40 – 50 degrees, In addition to which the Geiger go crazy. Of winter, the cold condenses moisture and high tension starts to get empty. At a minimum, the container must be airtight and you have to put the bags of Silica Gel. But even with all the care may not necessarily be able to make it work long.

      Our probes are made to make laboratory measurements, or with portable measuring set. When not in use should be stored in a dry place and reasonable temperatures. Environmental radioactivity measured outside is pretty much always the same, useless place a fixed probe outside. In the case of a nuclear accident there are already thousands of active and always available on the net.

      • Paul says:

        can I put it all out… though the probe want put outside the box to limit the length of unshielded cable will cm20, technically goes fine?

        • Livio says:

          You can do it, But why have two separate pieces with 20 cm of wire in the Middle, When you close it all together in a single probe.
          – A unique probe is easier to perfectly seal.
          – A probe with Geiger and Geiger Adapter is a complete unit, interchangeable with other sensors.
          – High voltage must stay all in probe. No wires with high voltage around. Much less if you think placing it outdoors.
          – Multiple threads are long and more electromagnetic fields induced by lightning increases. With twenty centimetres of wire, instead of two centimeters, the probability of counting lightning increases tenfold.

        • Livio says:

          Anyway “technically” You can do it. Twenty centimeters of unshielded wire make about 20 PF and not pain too the hose. If you use due care, mechanical seal on all, then okay.

  2. Luciano says:

    Hello Livio,using it as a smb20 probe on 60 CPM measured how many uS/h would be?
    CPM 60 = uS/h 0.3420 is correct?

    Thank you

    • Livio says:

      And’ more or less fair,
      If you have a tube of CPS/mR/h = 29 and don't count the BKG tube, 60 CPM make 0.348 us/h
      otherwise a BKG of 0.2 (normal for SBM20), make about 0.28 us/h.

      I to do these tests use the script “Geiger Simulator” you find examples of Theremino Script (to fill out and keep handy). Then I reckon by Geiger and not risk to make mistakes.

  3. Lucignolo says:

    Hello Livio
    I made two geiger with 4 SBM20 tubes each, one and’ mounted in a plastic container (and’ posted at Theremino the page after this) and the other in a die-cast aluminium housing with a thickness of 3/3, 5 mm, This for “block” beta rays and only detect gamma rays. I had placed two whiskers geiger nearby and set the bottom in CPS to have the usual value in nS/h of 85 in two graphs, This regulation and’ lasting several hours. The values in nS/h of two geiger (clearly closed in their respective containers) are different especially if it rains, and’ major in geiger in plastic container, While the CPM value and’ minor. I opened two Pulse counter and actually counts reflect the CPM.
    How come the CPM value and’ greater where nS/h and’ minor and vice versa, There’ an explanation?
    Thank you

    • Livio says:

      You set two different values in the BKG their tubes, the BKG greater subtracts more and is less uS/h although the CPS are more. I suspect you're asking too much accuracy in pipes that are allegedly made to work by many uS/h up. Virtually all Geiger tubes are made to find out if it's time to get away and it is already so be able to measure the environmental fund with a fair approximation.

      We've written repeatedly that the measures you can do are related. I.e. compare and say “This is a little’ more radioactive than this one…”. You can't measure the Bequerel and the accuracy that can be obtained are always very coarse.

      To have a minimum of precision is necessary to know well their probes and understand how they behave under various conditions. I'm sorry but I don't know tell you why these things happen, You must understand you doing tests. Probably just variations of geiger in time or parameter setting errors. What I can assure you that this is not software defects or counters, or USB or serial transmission.

      I once did an experiment, I measured the bottom BKG a SBM20 and then I tapped and rocked long. After this treatment the BKG had fallen very, If I remember correctly, almost 50%.

      This is not to say that pre-condition the tubes with a vibrator (also because I do not know what would happen the next day) but I mean that you should not expect much accuracy by Geiger (not because they are of SBM20, but precisely because they are Geiger tubes)

  4. The University of Regensburg organizes a conference on radioactivity twice a year since the Chernobyl accident. The conference in Autumn 2015 shall be dedicated for the first time to amateurs measuring radioactivity. In the past we had professionals only. The development done by amateurs is impressing however. Theremino MCA for example makes this technique, which was rather expensive in the past, available for hobbyists. We invite speakers to report about such projects. There is also an exhibition of measuring equipment.

    The location of the conference is a museum near Regensburg, Germany. Conference language is German, a talk in English would be appreciated also. Participation is free of charge.

    You can view the topics of the past conferences on this website:

    This is rather far to travel for people from Italy or France, We have participants from this countries however each time. Maybe there are also serious amateurs in Germany who read this. If you are interested as a speaker or participant please contact:

    Juergen Putzger
    Universität Regensburg
    Fakultät Physik
    93053 Regensburg


  5. Paul Zoso says:

    It would be a complicated thing, add a function to the software geiger to send mail when it exceeds a certain value or radiation level?
    I'd leave it on continuously to monitor environmental radiation and can configure an alarm.
    I'd also like to be able to load all the data in a database on my Synology nas and create a website (always on synology perhaps with joomla) with the real-time graph of radiation (, but unfortunately not an expert programmer and I wonder how much might come to cost developing a thing.

    Thank you

    • Livio says:

      Since the system Theremino is designed to separate modules, It is not fair to change the Geiger, for each new requirement. Would be fairer to set it, to write the data of radiation, in one Slot (the Slot to use you set in the options panel). Then it would take, two lines in Theremino script, to send an email or do other operations. You should find a friend who knows how to program. Unfortunately few of us and we cannot. You wouldn't know, but schedule requires a great deal of time, even for tasks that may seem small. For example, to act on something called synology and joomla, You should buy them and know them… whereby weeks of studies and experiments, at a minimum.

      With regard to send data on a site, the Geiger does it normally (Panel Logs), and there are dozens of sites, that they are doing.

      Here's some links:

    • Livio says:

      I missed the “how much would cost”.
      For this question you should contact a professional programmer, We do only free and Open Source projects.

      But there is good news!
      We are preparing the instructions to send mails with Theremino Automation. With the new version you can simply write the following type three lines:
      If Slots(1) > 1000
      SendMailTo foo dati_smtp testo_da_inviare_nella_mail password it at
      End If

      So if the Slot 1 (prepared by ThereminoGeiger) will exceed 1000 us/h, the mail will be sent.

      • Paul Zoso says:

        OK thank you very much , I'll wait for info to use Theremino Automation, in the meantime I will see if I can get something, If I will share it all here.


  6. Paul says:

    Salve, I was interested in understanding how estimates the error range of Geiger. I thought it was up by the square root of the number of counts detected but from source I saw that and’ so’ only between 100 and 10000 pulses (even though from the comments to the code it appears that initially were not present this distinction). There’ any particular reason why under 100 and above 10000 and’ was decided to use a different Predictor?
    Thank you and congratulations for your program.

    • Livio says:

      The statistics says that the error is in proportion to the root of the number of pulses and this is definitely right, But what is meant as an error can?

      We talk about errors that will not be exceeded in 90% of cases, or in 99% of cases? If you intend to errors that will not be exceeded at (even with the most unlikely that could happen every 1,000 years) then the values would be much higher, of percent we are used.

      What we were interested in showing Geiger, It is not a pure as mathematician, but a percentage that, “in most cases”, was consistent with reality. That is a fact that it was a good estimate, What to expect in the next minute, or in the half hour following, or in the three hours following (Depending on the sample activity).

      This is basically to predict the future…

      And we have verified in practice that, for very high counts (> 10000) and very low (<100), the reality didn't match the theory. We approximated roughly these two cases, with root fourth and a linear relationship.

      There are two alternatives commented in green, You can try them, the third is exactly equal to the statistical theory.

      I don't know tell you why our formula works better than pure statistical theory. Probably the "risk" to err, perceived by humans for short periods, is not the same as the "risk" for a long time. In other words you must modulate "confidence" at 90% or to 99% or to 99.9% Depending on whether the seconds, minutes or hours.

      If you find better explanations write them here in the blog, for the good of all geigeromani.

  7. Marco says:

    some time ago I came across this site accidentally and I was pleasantly surprised by the technical level of proposed projects. I recently developed a sensor and an app for Android (RadMeter) functioning much like Geiger. The app is free and can run on virtually any sensor (using interfaces such as Geiger Adapter or Checker :-)).
    I am convinced that this app has since now features over Geiger Pocket, used here in the past, but I think it can be further improved by suggestions or recommendations collected within this community.
    I would be very happy if RadMeter could be mentioned within this site or if it could be proven by users thereminici.
    In any case, I congratulate you for the great job you're doing outreach.


    Here is a link to the app:

    • Livio says:

      Very nice application, the'll link each other soon with some pictures, Maybe the page of GeigerAdapter. Send an email to Alexis that he often uses smartphones for radioactivity and write surely his tests on our Facebook and Twitter pages.

      Before proceeding, however, you should explain two particular:
      – The sensor SS05 that sensitivity has? (CPS/mR/hr)
      – How much is it? (If we're going to advertise would be nice at least to someone writing prices – products without prices are lousy – only in Italy we have this mania to hide everything)

      And then… no hurry, but in some future release… would it be possible to add the BKG to each tube and take them into account in calculations? Otherwise the bottom of scale (that is the most important) suffers from an exaggerated non-linearity and provides values systematically mistaken (even the 200 or 300%).

      • Marco says:

        Thanks Livio for availability and for the speed of response.
        Here's my replica:

        >- The sensor SS05 that sensitivity has? (CPS/mR/hr)

        >- How much is it?
        I agree with your account, in fact the cost in question is written on the site :-) and is established when 59 Euro (See also
        I would like however to point out that the app is not bound to using this sensor, It is present in the internal database on a par with other sensors and Geiger tubes without any preference of treatment. On the site I tried to give directions, and if necessary I will look into the matter, regards the interfacing with different types of sensors application hardware.

        About the value of BKG it is already accounted for in the calculations and is present in the database of the sensors. Because I felt very valid program Geiger, I tried to make the app so that it was very similar to it and was of immediate use for users already accustomed to this program. Printing errors, the calculation algorithm of RadMeter should be equivalent to that of Geiger.

        If Alessio deems interesting this app and want to delve into any technical detail about it can contact me freely in pv via email.


        • Livio says:

          I hadn't seen the price (a little’ Altino if it is a single BPW34…) nor had noticed the FAQ page. There are now more info, glad, Thank you!

          Very good your program, you added the BKG! And you notice that responds well, makes a nice chart very significant (practically the same visibility of Geiger), has the logarithmic scale and also does error bands! Very nice!

          And also very nice round logarithmic scale!

          You will do a good review but to be clear before on some particular. We do not like recommending items to 50 Euro, If we are not sure that go well. How can they be 5 CPM/mR/hr?
          From our trials it would take dozens of BPW34 in parallel and the total parallel capacitance stoop so much the pulse height, making it unstable and precarious the limit between pulses and noise.

  8. Joseph says:

    Hello Livio, I don't know how to say this….but really congratulations for the work you do. I read the manual of the CNC latest version and you have done a tremendous job. I can't wait to get to work on CNC. Meanwhile I'm still ravanando on theremin, the VST etc and I'm having a great time.
    Two things, however, I wanted to ask in reference to Ionic room for radon.
    I saw a while ago that you are working with one Chamber in stainless steel (and I saw that you have taken the copper rods 2 mm…I while ago I suggested to use them but I recommended the square ones that weren't going well):
    1) What do you use as an insulator of the wand?
    2) There is a tutorial for the construction of the room in stainless steel or can I follow mutatis mutandis the old one?

    Thanks again…Joseph

    • Livio says:

      We use chopsticks to brass tube 2 mm in diameter. It is found in the shops of modelling, for tubes of models with petrol engine. To isolate them okay any plastic or nylon with a 2 mm hole. Sure the finger FET, must be completely inside the inner Chamber, fully shielded from electronics and from external electric fields. Brass is an excellent material for electrode and the advantage of a pipe, compared to an electrode full, is that the relationship between rigidity and weight is much greater, Why shaking the room pulses do not occur.

      Ion Chamber treatment of mechanical construction is even more important than what you thought at the beginning. A room at ions with slight defects (residual dust of construction, blunt tips, rough parts, Rusty or not rounded) It can work well for a long time and then stop working, just the shakes or humidity exceeds a certain level.

      For the construction of the room there is still no stable project, mechanical solutions have been tried, all difficult and also horribly uncomfortable to fit the electronics.

      However the research continues, a test Chamber is at the harp to verify the calibration and maybe we can even eliminate double room outside and keep the exterior in massa. For now let us not create too much confusion, with intermediate versions that are outdated before they even finish it. As soon as we publish them valid and definitive solutions. It will take months, as it took for the CNC, but worth the wait.

  9. luciano says:

    A salutone to all,After quite a long time I rewrite on this blog for chiederen to Livio information this time on the raspberry.
    I saw that you created a img (ENV) for this mini pc,the question is also works with Geiger?.
    I still in the drawer of his master and geiger hired time and would like to experience what.
    the raspberry is the new one 1 Jig with 4 CPU-



    • Livio says:

      Until last year, between Mono, Libusb, coprocessor not implemented and slow running, use the Raspberry was so difficult and uncomfortable that none of us has continued the tests. Then last year came out Tablet, just more expensive than a Raspberry, that give so many accessories and performance that they prefer in any situation. Even if only for the fact that having it all do not bind the USB ports for Wifi and Mouse. But especially because, having a true Windows, the installation is easy and fast and precise execution. Besides, it also becomes possible to use Visual Studio and debug the software. On Raspberry you should use “Mono Develop” that is extremely uncomfortable, If not impossible to use, for debugging.

  10. Livio says:

    The new version 6.3 by Geiger is here:

    The improvements to the hardware of the ions are here:

    The discussion on measuring units “Concentrazione” and “Activities” is here:

  11. Nicolas says:

    Good morning, I am developing a project using an Arduino Uno and should I attach two Geiger then should I read the results of measurements on arduino.
    And’ arduino can be connected directly to the adapter geiger and read the input from the sensor?
    Possibly you can, through the master, program the arduino ide to interact in the same way with theremino without having to arduhal?
    Thank you

    • Livio says:

      QUESTION : You can connect directly to the adapter arduino geiger and read the input from the sensor?

      It is possible to, provided programming into the Arduino needed.
      You will have to use a digital input and probably interrupt type.

      QUESTION : Possibly, through the master, program the arduino ide to interact in the same way with theremino without having to arduhal?

      REPLY :
      The Master (If you mean the form Theremino Master) It has nothing to. The arduino is programmed with the Arduino IDE.
      Not to pass by the ArduHal you should develop an appropriate firmware to the Arduino and also an application on your PC, and both should communicate with each other through a common protocol, so that they can understand each other. Basically you should rewrite a firmware for the Arduino similar to what we wrote, and a PC software similar to ArduHal.

      I may not have understood well what would you do if so explain it better.

      • Nicolas says:

        Hi,, I'm trying to build a cosmic ray detector in coincidence as described in, and if possible try to read this data using the arduino serial monitor.
        With the arduino programming I can handle but I never tried to interface sensors via interrupt pins. How do I read the surveys and possibly the coincidences between the two systems?
        Thank you,

        • Livio says:

          I don't know if you can do it all in software. Probably the door AND revealing the connections it takes. Anyway you could try.

          With respect to suggest how to write the firmware on the Arduino I'm sorry but I know too little, and I don't know how (What if) You can use the Interrupt so fast enough to reveal the connections without the help of the hardware.

          • Nicolas says:

            So if I were to be able to use Arduino to read data should I go for Theremino master and the PC software. And if instead, instead of Arduino, I used a Raspberry Pi 3B remote through SSH you can always write a Python script to obtain measurement results to coincide, directly attacking Geiger adapters to card?

            Thank you,

            • Livio says:

              The GeigerAdapter can be connected, directly, any microprocessor, It's an Arduino, a Master unit or even a Raspberry. As well as any other “dude” can read digital inputs.

              However, it must be that these inputs are read at the same time, time very accurately, because a few tens of microseconds can mean the difference between a coincidence (Cosmic Ray) and a simple case of radioactive impulses separated, due to various isotopes present in the environment.

              So the firmware (or software if you are talking about raspberry) should be written properly and I can't tell you if it's possible and how hard would it be to write something like.

              We have chosen a safer road and precise, that, however, requires some’ of hardware. The hardware does the dirty work and then you can easily count the pulses, with a simple digital input, no hassle of times.

              • Nicolas says:

                All right, Thank you.
                To develop the project do you recommend so the purchase of GeigerAdapter with a Theremino Master, If I understand?
                To do then so the Master can send the signal by coincidence to Arduino or Raspberry instead how could I do?
                Thank you very much

                • Livio says:

                  There must be something misunderstood the basis. We do input output for PC, No PC is not always in line.

                  So it takes a PC (or a Notebook or Tablet), It must be a Windows PC, not an Arduino or a RaspBerry or a Android or Mac.

                  To use an Arduino (or other similar which are not PC) would the Geiger Adapter, and perhaps the connections plate, but then you'd have to write from scratch all the firmware and software.

                  None of our applications, our firmware, of our software work without PC. And even our modules (I mean the ones that connect to USB, that is, Master, Slaves and Adc24) can be operated without PC. Is there any exception, for example MAC with Windows emulators or Linux with Mono, but it's hard to get them to work, too many issues. Why not recommend them, unless you know exactly what you want to do and how to do it.

  12. Livio says:

    Alberto wrote
    I need to measure the degree of ionizing radiation present in game meat (wild boar) given to me by a friend of mine.

    Your solutions seem better than buying a better counter credited (and expensive).
    I tried following the links on the document found on the internet (a pdf file) but at the moment it doesn't seem to work.

    Could you give me some information about how to obtain and purchase the various units (feed module + form “master)?

    For pipe, reading on other forums, I thought of buying a LND-7317, that would seem to be one of the best for this type of circuitry.

    You could build a simple counter as explained here:

    But to measure low levels of radiation would be better to use the application Geiger and in this case we would also like to a PC (or tablet), as explained here:

    The components can be found on eBay or

    Or write to Lello and could build around Him:

    Other useful links:

    – – – – – –

    About the Geiger tube, what you have proposed is very expensive and is found only from the manufacturer LND in the United States. Among shipping and customs fees you pay it a blunder. Also it is very delicate.

    We recommend buying, on eBay, four tubes SBM20 and put them in parallel. You will have a feeling almost double, spend less, and no risk of breaking the delicate mica window.

    The SBM20 feel no alpha radiation but only Beta and Gamma, but in your case (and almost always) the Alfa does not serve.

  13. Marco says:

    I'm testing a si8b with Geiger adapter Theremino.
    After a few seconds of measuring the sensor goes crazy and the counts become huge.
    Have you ever worked with probes of this type?
    There are similar problem?


    • Livio says:

      All tubes geiger (if defective) They behave as you say.

      Try to do work at lower voltage, 250 or 300 volts to see if you download more, and if it still fails to work. But most likely there is nothing to do, must be changed.

      I have a doubt, is not that the food on the contrary (positive instead of the negative) ?

      • Marco says:

        Yes, It was contrary…
        now it works correctly.
        He may have been damaged to work on the contrary?

        Thank you

        • Livio says:

          The protection resistor which is in series to the pipe (the last resistor that is in Geiger Adapter, before the positive that goes to the tube) however limits the current to a very small value, so that the electrodes are in the tube last for millions of discharges.

          Connecting it to the contrary, the mere fact you download much more frequently than usual, abbreviandogli the lives of several thousand discharges.


          I take this opportunity to remind everyone that the Geiger tubes are connected to the Geiger Adapter on the two pitches in the top and bottom, and not to the test points and the voltage selector.

  14. or says:

    I have tested lnd 7145 with Geiger Adapter V3 Theremino. It works well but the voltage decreases continuously and after some time the count rate reaches Zero (when voltage goes under 380 volt).
    I’ve increased c2, c3, c4 and c5 value but again the voltage decreased as well with lower rate.

    • Anonymous says:

      Increasing capacitors is not a solution, it orks perfectly with the normal values.

      The only problems could be:
      – Moistured air (over 70%) (try to clean the PCB with dieline or trieline)
      – A capacitor failure
      – Some resistor failure
      – Some other compionent failure
      – A Geiger tube defective

      If you can not repair it you can send it to the seller and it will be changed with another working without charges (except postal charges).

      Please write to us if all will be ok.

      • or says:

        Thanks for your reply.
        But I designed the PCB and assembled it myself.
        The high voltage value drops with load. For example when i put 5 uCi Co-60 on the Geiger tube, the voltage drops to around 430 volt and for 20 uCi Co-60 it’ll be around 400 volt whereas I’ve adjusted it on 490 volt.
        Is it possible to increase the output current?
        Best Regards

        • Livio says:

          If correctly working our GeigerAdapter does not changes the voltage as you write. Maybe you have not used the low leakage zeners listed in our schematics?

          You have used the Geiger Adapter V3 schematics?
          Have you changed some component with “similar”?

          • or says:

            Yes، schematic v3.
            I just replaced MMSZ5270, MMSZ5261 and RS1KL with 1N5270, 1N5261 and US1M respectively.
            Today I tested Adapter v1 and it works great. Fortunately the voltage just drops 3 volts for Co-60 with 20 uCi.

            • Livio says:

              I can’t figure out what the problem might be.
              If it does it sporadically maybe it could be the moisture that causes a leak current on the PCB

  15. Livio says:

    Gabriele wrote us:
    I'm doing a little’ Research on how to build a Geiger counter and discovered your site.
    First of all congratulations for the elegant solution for the power supply.

    I have a question on the output signal.
    Because you have chosen to use the high side sensing with the capacitor for the DC block, instead of doing the low side sensing, which can be connected directly?

    Even a small parallel capacity greatly increases the discharge current
    worsening the protection given by the resistor for current limitation
    and then decreasing the life of the tube.

    With the negative side of the grounded tube there are advantages:
    – You can place the tube on a PCB, with the ground plane parallel without increasing the capacity.
    – The connections to the tube require less attention.
    – The only connection that should be kept short, and low-capacity, It is the positive.

    In addition to current capacitors 400 volts are nonsense,
    so that a 47 PF to 630 Volt could be microscopic.

    However, we have used one 0805 not to exaggerate with the miniaturization
    and to keep loose insulation on PCB.
    (Note the care with which we designed the PCB and its insulation)

  16. Livio says:

    John asked us

    I'm doing a little measuring radon, as “sensor” I am using 9 BPW34S diodes closed an a metal screen (those RF pcb). This causes the “sensor” it can work? detects alpha? or completely fencing around?

    The alpha rays can not even get over a few centimeters in air, nor will any solid body. However, theoretically it would be possible to pass the air containing radon from a tube and pull it out from another.

    But in your case the problem is another, the sensitive area of ​​the diodes is very small, a fraction of a cubic millimeter, so compared to our room in ions from one liter of sensitivity ratio is around ten million.

    This means that:
    – With the ion chamber collects approximately one pulse every five seconds and you can make a measurement in half an hour.

    – With the diodes (also were 100 diodes, then a sensitivity ratio of a hundred thousand) you would have an average pulse every 500 000 seconds (5 days) and then you might have a significant extent in about 28 years.

    There are methods for concentrating electrostatically Radon of a diode, but require high voltages and a difficult construction, which also attracts dust and soon gets dirty to no longer work. And in any case to a stable measurement require days.

    I bought a while ago airthings sensor, the sensor is a PIN diode in a closed room with aluminum painted plastic (it is conductive, tested with multimeter). The tensions that I could read on the card are of the order of 10V.

    The diode is biased with about 6V, and measure a few uA. I agree that it is little more than a toy, but what measure is completely unreliable?

    With that sensor measuring current and does not “count” pulses.

    The current is unstable so it is a significant measure current only if there are many Alpha, something like ten thousand times alpha normally produced by radon there is in the environment.

    With very few alpha that there are in a normal environment, It is measured only the random noise of the diode current and the variations of the current produced by the temperature.

    To measure a significant current should avvicinargli Torio with a net or a piece of Americium, but this would serve no purpose, because you'd know a priori what have you approached the sensor.

  17. Erich says:

    Hi Livio,

    I slowly become crazy because I cannot download the Theremino Geiger Software.
    Can you help me, because the link
    is a dead-end-street.

    Best regards

  18. Plavic Acid says:


    I can’t figure out – where Geiger Counter keeps log files recorded with the “Log to text file” button. Any clues?

    • Anonymous says:

      In the same folder of the “Theremino_Geiger.exe” application there is a folder called “Extra”.
      In the “Extra” folder there is a file called “Log.txt”
      Every new log line produced is appended to the “Log.txt” file.

      If you do not use the CPH format you could also set the “Export with header” flag that produces an evident title in the file for every new acquisition start.

      To have a new file you could delete the “Log.txt” file.
      Or you could archive the file changing the file name.

  19. Manuel P. says:

    Hi everyone, i am testing 2 ion chamber at the same time, using 1 master V5 under an old eeePC Asus, and i have found that LOGs are one for both chambers, than please attention if use 2 or more input (ion chamber or geiger). Every LOGs show you a double time, first row for 1st chamber(or geiger) and the second one for 2nd chamber(or geiger) alternated. This happens in my system with software Geiger V6.7 and i think it’s normal (not so confortable but ok). Then i export data and, under excel i can filter rows and select camera 1 or 2 and manage data. Remember to rename every time (before new measure) the LOG name, because every new start measure, overwrite the default LOG.

    • Livio says:

      I don’t know how you’re doing it, you didn’t write it, but I imagine you’re using two Theremino_Geiger applications.

      In any case the Geiger application cannot write two logs.

      If you really want to do this you should use two Theremino_Geiger applications and NOT make them write the LOGs

      Then you should set the Input Slot different for each App
      And you should set a different Output Slot for each App
      And finally you should use the Theremino_Logger12 application to make a single LOG file taking the data from the two Output Slots that you have set in the two Geiger Apps

      • Manuel P. says:

        Hi Livio and thanks for your replay. You are right, i am using (for test and my knowledge) 2 geiger app and 1 hall app, setting slot 1 and 2 for chambers. I haven’t tried to use logger app (best solution for Logs, as you wrote) but with this configuration happens that geiger app start really with 1 new log, with double data (time are duplicated, values are different every 2 rows) and for my test it’s ok. I don’t know if this was forecasted, but is working fine anyway. I will send to you a mail with details for these tests. thanks again

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