Blogs for Geology

Requests, comments and ideas are welcome.

  1. Marcin says:

    Thank You for Your respond.
    Yes, I would to use Your solution.
    1. Proper power supply – dual polarity symmetrical power supply + /-12v correct?
    2. please help me calculate the three resistors of the divider to limit voltage of the output signal to 3,3V
    3. How to calculate proper resistor which need to be connected between the 12 volts?.

    Best Regards,

  2. Marcin says:

    Thank You for quick answer.
    Message is clear for me – google translator works well:)
    I would to use ADC24 module to get maximum resolution.

    > connect power supply +12(D) -12(And); GND -Power COM.(C) to my geophone
    > connect geophone to voltage divider
    velocity signal output(A) 12v -to V1,V2
    HOW signal. (B) – to V1,V2
    >connect voltage divider output ADC to Pin signal 1 of ADC24 module ;
    geophone signal COM. (B) – to Pin Ref. 1 of ADC24 module ;
    >connect ADC24 module to Master module acc. to ADC24 manual
    >All cables shielded.

    Please corect me if something is missing or misanderstooded.
    Thank You for help.
    Best Regards,

    • Livio says:

      – Connect power supply +12(D) -12(And) to geophone
      – Connect power supply GND to geophone GND
      – Connect geophone GND to GND (all triangular symbols)
      – Connect velocity-out to “INPUT” (resistor R1)
      – Connect 12 volt positive power supply to V2 (resistor R2)
      – Connect “ADC” out to one of the 16 Adc24 inputs
      – Connect Adc24 GND to GND (all triangular symbols)
      – Connect ADC24 module to Master module acc. to ADC24 manual

      Providing to position the resistors near to the Adc24 it is not necessary to use shielded cables.

      The only cable that needs to be shielded is the long cable that goes to the geophone (if it is long more that some meters). With a shialded cable the geophone cable could be long 100 meters and more.

      Remember that the 12 volt positive, connected to the resistor R2, must be stable and low noise.

  3. Marcin says:

    Thank You for responsd a lot. I have last but not list:
    1.Geophone s-500 has pin out “AS SIGNAL.” And “SHIELD AND POWER COM.” which one should I use as geophone GND?
    2.what I need to do to cuttoff high frequency?. I would to measure only low frequency the best will be range 0 to 50Hz.
    3. Is it possible to use somehow Your’s wifi module with ADC24 without influence to measured results?
    4. Can I connect Theremino Master by UART USB with Ni MyRio 1900?

    Best Regards,

    • Livio says:

      1) Connect the SIGNAL-COM to GND (resistors GND and Adc24 GND)

      2) Your geophone has a band pass of 100 Hz. Reducing it to 50 Hz will not change significantly the measures. Anyway, to filter (approx -3B at 50 Hz) you could add a 2.2uF capacitor from ADC to GND (in parallel to the R3 resistor). The capacitor could be a polyester type (not electrolitic and not ceramic).

      3) I do not understand this question. Our Wifi module, called NetModule, is NOT connectable to the Adc24.

      4) The theremino Master is only connectable to a PC (or Tablet) with Windows operating system. On the PC (or Tablet), only the HAL application is capable to read the Master data, via USB. To connect the Master to a non-Window device you should write an application similar to our HAL, a very, very long work, also for an expert programmer who knows perfectly that device.

  4. Marcin says:

    Thank You for help a lot. You mention that I need stable power supply +/-12VDC with low noise. I found Tracopower tvn3-1222 DC-DC converter 3W with ripple and noise: 10mVp-p.

    I would to use it for geophone and voltage divider.It will be good enough?

    • Livio says:

      Probably the geophone supply is internally stabilized and is not influenced by power supply instability and noise.

      For the voltage divider the “regulation” (about 1%) is OK, but the noise (about 10 MV) could add a significant noise to the measured signal. Or maybe not, because of the high frequency of the ripple caused by the switching supply.

      Eventually, try to supply the resistor R2 with a separate 12 volts (a bench stabilized power supply). If the noise decreses, we will find some solution to eliminate the 12 volt noise.

      1) First solution could be, to add a 100 ohm resistor, and then a capacitor to ground (1000 uF 25 volt electrolytic) before the R2resistor.

      2) A second, and more powerful, solution could be to add a 9 volt regulator (78L09) between the 12 volt and R2, and then recalculate the divider resistors.

  5. Marcin says:

    I think that I found better converter: 1W +/-12VDC with ripple and noise max 8mVp-p , typical 6.7mVp-p and acc. specification note ripple can be decreased to 5mVp-p when proper capacitor and inductor is applied to output.

    I would to use as power source battery pack ( 5V) . I would like to use the proposed solution to additionally reduce the noise by adding a regulator (78L09) but how to recalculate these resistors?. I admit that I’m not too familiar with electronics at this level. Could You help?

    • Livio says:

      Do not use a battery pack, the 5 volt of the USB is better.

      Resistor values with a 9 volt regulator connected before the R2:
      – R1 = 10 k
      – R2 = 7.5k
      – R3 = 2k

      You could compose the 7.5k and 2k resistor using two normal resistor in parallel.
      In internet you will find many utilities to calculate paralleled resistors.

      For example you could create them with the following resistors:
      7.5k with 8200 and 82000 resistors
      2k with 2200 and 22000 resistors

  6. Marcin says:

    It works! :)
    I connect signal “ADC” to ADC24 input and GND to ADC24 GND .

    How to connect another geophone -this one is not this same, this is geophone without external power supply Mark products L-4, 2 cables ? When I disconect first geophone I can use L-4 by connecting it to ADC24 inputs (input 1, input 2) and it works properly, but if both are connected to ADC24 there is some conflict.

    Best Regards,

    • Anonymous says:

      The second you have to connect to IN3 and IN4 and configure it as “Differential”
      There should be no conflicts, you have something wrong, perhaps Slot, recheck all.

  7. Marcin says:

    You have right. Now both working fine. First should has configured INP 1 as” pseudo differential” second geophone as You mention should have configured INP3, INP4 as “differential”.
    Thank You.

  8. PC72 says:

    Hi Livio.
    I’ve read your reply in 2015 concerning a question about magnetometers and gradiometers. I intend to build both but as you said yourself, at least up to 2015, there were none built. So I hope you can clarify some doubts. The PDF document by Joseph Carr mentions AD557, LM2917, etc. but the theremino text says nothing of these are necessary and in fact could affect stability. So all that is needed is the geomagnetic adapter and the master.
    For a gradiometer for instance, as I understand, the sensors go to a schmitt trigger type such as a 74HC14 then to a flipflop like 74LS74 and then to the system pin theremino.

    In the original PDF, this last part goes to a voltage converter. But if this is not used, then the changes in magnetic field will be monitored trough frequency changes of the sensors.

    This is more or less clear so far to me. But once the output reaches the theremino master and goes to a computer with HAL, then what happens? How can I monitor the signals? Is a special software required? Do I need to design one? What about 3D visualization?
    Also regarding bluetooth connection? How is it accomplished?
    Thanks for your reply in advance. I am new to the theremino world and I am just starting to get everything together.

    • Livio says:

      These questions are difficult to answer. My advice is to open some of our applications and try them.

      Starting from:
      – Slot viewer (open two and find out that they communicate through the Slots)
      – Signal Scope (move the slots with the Slot Viewer and view the changes)
      – Wave Generator (use it to send waveforms to Slots)

      Then you could buy a Master and try it with him, but you don’t need to spend. You can also understand the system using only software applications.

      The complete list of the applications is here:

      And’ difficult to answer these questions. My advice is to open some of our applications and try them.

      starting from:
      – Slot viewer (open an existing two-and discover that communicate through the slot)
      – Signal Scope (move the slots with the slot Viewer and display the variations)
      – Wave Generator (use it to send waveforms to Slot)

      Then you purchase a Master and try with him, but it is not necessary to spend. You can tell the system using only software applications.

      The complete list of applications is here:

  9. iotservice says:

    hi it is possible to use theremino as a board to acquire signals to build a georadar , in your opinion it is better to use one or two fgm as data acquisition devices or to use an RF system with transmitter and receiver type metal detector for the PC software I would opt for dolfrag

    • Anonymous says:

      The sampling rate of our system (maximum 500 samples per second) it is not enough for georadars. So our Adc24, and our Master and IotModule modules, and our HAL and IotHAL applications cannot be used.

      To make a georadar you have to do everything inside a microcontroller, not on a PC like we do, and only at the end can the results go to the PC, via serial line and via USB.

      A suitable module for doing these things could be Arduino Nano, but it also takes a lot of high frequency electronics. And the results that can be obtained are quite poor, here you can see examples of what can be seen even in simple cases (a bridge):

  10. Giacomo says:

    Hello everyone. A clarification. I would like to prepare a small seismometer with an accelerometer adxl335 also using the Theremino ADC24. In the instructions of adc24, in Pagnia 17, there is a picture of three 1uF capacitors of blue color. Sorry for the question: but what kind are they? Thank you

    • Livio says:

      As long as they are not electrolytic (must not have polarity + and -)
      If you want them very small get SMD ceramics with houses 0805
      Otherwise the usual teardrop ceramics or flat ones.

      The blue ones in the photo are ceramic capacitors with the two wires coming out of the side.
      There are also wire cones that come out in axis.
      Or other chubby ones that look like a big drop of paint.

      It is enough that they are ceramic and 1 uF and they are all fine.

    • I don't recommend using accelerometers that have already been tested in the past) but of poor sensitivity ( even the relatively expensive ones ) use geophones from 4,5 Hz, even 1 Vertical only.

      In There are a few designs with accelerometers, Abandoned Projects.

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