Pressure sensor device amplification

Hello everybody,

I am a student who is developing a pressure sensor device for a medical application. I need to measure pressures between 0 and 50mmHg. Therefore, I am using arterial pressure sensors that suit my purposes (https://www.icumed.com/products/critical-care/blood-pressure-monitoring/transpac-it.aspx).
I need to amplify, filter and condition the signal before Arduino UNO can read it.

I've designed an schematic that I think can work, but now I am trying everything in a protoboard and it does not work. I have tested with a voltmeter partial voltages and the DCDC converter seems to be not working good. It does not give any output signal. I have checked again its datasheet and seems like it has a CTRL pin... but I do not really think it is the reason why it does not work. (https://eu.mouser.com/datasheet/2/468/RS-S_D_Z-958418.pdf). I do not know if the DCDC converter is broken or if I have performed a mistake before...

I would be very very very thankful if any of you could give me his/her opinion.
I attach the schematic and two photos of the protoboard.

Thank you very much!!

Hi,

At a wild guess, the wires that should be in pins 6 and 7 are currently in 7 and 8 (I'm saying that by counting the breadboard holes and where the wires are in picture 1 and what the datasheet says for the single DCDC converter, but that wiring would still be wrong for the dual converter, I think). It would explain why there's no DCDC output.

Thanks. I followed your instructions and I considered to remake the schematic and correct its mistakes. (I do not have Altium license anymore so I did it as I could).
-->I have corrected the pins in the DCDC converter according to the datasheet and also the pins in TL062.

I do not really know why, but now the DCDC converter seems to be working but it gives almost +14V in Out+ and -10.10V in Out-. Instead of +12V and -12V that is what I was expecting. However, I think this should be enough to supply to the INA128 and TL062. However, it still not working...

Hi,

I do not really know why, but now the DCDC converter seems to be working but it gives almost +14V in Out+ and -10.10V in Out-. Instead of +12V and -12V that is what I was expecting.

Click to expand...

Your expectation is wrong: The DCDC is single output = two pins. You can measure this single ouput voltage by connecting your voltmeter to these two pins.

***
My recommendation:

* Your PCB input is +12V (referenced to GND) --> use this everywhere you need +12V
* Disconnect DCDC_+Vout and connect it to GND.
* Disconnect C4
* now DCDC_-Vout is -12V (referenced to GND) --> use this everywhere you need -12V

Klaus

Hello everybody,

I manage to solve the problem!!!
Thank you to all you!

jts

Hi,

a forum is meant that others gain from reading this thread.
Thus you should describe the source of the problem and how you solved it.

Klaus

KlausST said:

Hi,

a forum is meant that others gain from reading this thread.
Thus you should describe the source of the problem and how you solved it.

Klaus

Click to expand...

I am so sorry, I thought I had attached the correct schematic but it was not upload. I think it is now uploaded.

My problem was that two wires of the pressure transducer were not working correctly.

Best wishes,

jts