How to measure voltage on a ox sensor?

[Agro]

Hello, I have a pressure chamber which brings sensors up to 3 bar. I can measure voltage by a simpel multimeter. I was told I need a resistance between sensor and multimeter, otherwise measurement is not correct.

Which resistance do I need? 1 Ohm? 1 Kiloohm? ........?

Thanks for your help.

 

[LFMarm]

Hello, I have a pressure chamber which brings sensors up to 3 bar. I can measure voltage by a simpel multimeter. I was told I need a resistance between sensor and multimeter, otherwise measurement is not correct.

Which resistance do I need? 1 Ohm? 1 Kiloohm? ........?

Thanks for your help.

Why not use the head of your rebreather to read the sensors?

 

[Agro]

It's my friends sensor, not mine.

 

[Snusmumrik]

Hello, I have a pressure chamber which brings sensors up to 3 bar. I can measure voltage by a simpel multimeter. I was told I need a resistance between sensor and multimeter, otherwise measurement is not correct.

Which resistance do I need? 1 Ohm? 1 Kiloohm? ........?

May be you're being told that you need a load resistor (for sensor) in parallel with multimeter?
In such case you need 10 KOhm 1% load resistor - it's typical value.

 

[tongl]

The cell itself is a current source, but the packaged sensor should have a sampling resistor and temperature compensation built in already. ADC in digital multimeter should be a high impedance input, shouldn't need additional load resistor to read this voltage source.

 

[Agro]

I got information from Divesoft. In fact I do need a 10k Ohm resistor as Snus told us.

Problem seems to be solved, I will try to measure by multimeter.

 

[Dsix36]

I have heard of needing a 10k ohm resistor inline on the positive side of a sensor in order to give isolation when sharing sensors with multiple PO2 readouts (Shearwater is one that needs the resistor while the revo dream does not), but never just to read the voltage. Can someone please explain this to me. I have been sticking a mutimeter across the sensor pins for years to read the voltage without any type of resistor.

 

[Agro]

I have heard of needing a 10k ohm resistor inline on the positive side of a sensor in order to give isolation when sharing sensors with multiple PO2 readouts (Shearwater is one that needs the resistor while the revo dream does not), but never just to read the voltage. Can someone please explain this to me. I have been sticking a mutimeter across the sensor pins for years to read the voltage without any type of resistor.

Oh, and it worked?

I will use a multimeter as well.

 

[Agro]

I was discussing this topic with several "experts". I got
- no resistor at all
- resistor in line on any side (pos. or neg.)
- resistor must be in line on pos. side
- resistor must be between pos and neg. As far as I understand this is what Snus tells us

No I am confused....

 

[Snusmumrik]

I was discussing this topic with several "experts". I got
- no resistor at all
- resistor in line on any side (pos. or neg.)
- resistor must be in line on pos. side
- resistor must be between pos and neg. As far as I understand this is what Snus tells us

No I am confused....

a) no resistor at all - if sensor manufacturer stated this, or if simply multimeter shows
"that works".
b) resistor between pos and neg - if sensor manufacturer strictly stated this.
Typical value - 10K 1%.
c) resistor inline between one sensor pin (pos or neg) and wire to computer. This allow some "isolation" if two computers are connected in parallel to one sensor.
Note. With two computers there must be two separate resistors - one for each wire (for example - pos) to computer. neg wires can be connected together with neg sensor pin.

Personally - i've never tried variant c. All my exprerience was around a and b.