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 electrolitic) 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.

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