Geologia

Blog per la geologia

Richieste, commenti e idee sono benvenute.

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?.
4.OK

Best Regards,

• Livio says:

Rispondo in italiano perché mi viene più facile. Hai trovato difficoltà a tradurre il mio messaggio?

Riguardo al partitore, eccolo qui:
https://www.theremino.com/images/Adapter_12-bipolar_to_3.3-single.jpg

Se userai gli ADC del Master fai attenzione che, superando 0.3 volt negativi, o 3.6 volt positivi, la comunicazione con l’USB potrebbe interrompersi. Non si rompe niente ma potrebbe essere un fastidioso problema. Invece l’Adc24 e il NetModule sono più tolleranti.

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.

summarizing:
> connect power supply +12(D) -12(E); GND -Power COM.(C) to my geophone
> connect geophone to voltage divider
velocity signal output(A) 12v -to V1,V2
signal COM. (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(E) 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:

Hello,
Thank You for responsd a lot. I have last but not list:
1.Geophone s-500 has pin out “SIGNAL COM.” 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.
https://www.tme.eu/pl/Document/67cfcd470a55ea647fc1ff779c263b38/tvn3-datasheet.pdf

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 volt (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.

5. Marcin says:

Hello,
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.
https://pl.mouser.com/datasheet/2/281/kdc_nmv-10836.pdf

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 = 10k
– 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

• Marcin says:

Thank You a lot:) I will feedback when it will work.

6. Marcin says:

Hello,
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:

Il secondo lo devi collegare a IN3 e IN4 e configurarlo come “Differential”
Non devono esserci conflitti, hai sbagliato qualcosa, forse gli Slot, ricontrolla tutto.

7. Marcin says:

Hello,
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.