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DrDAQ + pH and ORP

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DrDAQ + pH and ORP

Postby Guest » Tue Jun 07, 2005 2:21 am

Hi,

I want to measure both pH and ORP at the same time with DrDAQ. Will the external "sensor adaptor" that you sell allow me to connect an ORP probe to DrDAQ.

I think the ORP probe needs a singnal amplifier similar to a pH probe.
Does the sensor adaptor come with such an amplifier, and does it have a BNC connector.

If not, could I use one of the external phone jack connections of DrDAQ, and build a cicrcuit like the one shown here to amplify the sinal using the INA116P Amplifier. Will this work?

http://www.picotech.com/experiments/ph-measurements/
Guest
 

Postby Sarah » Tue Jun 07, 2005 8:58 am

Hi

Thank you for your post.

I am not sure what an ORP sensor is and what type of output it gives. The compatibility of the sensor will depend on it's output. Can you give me some more information as to this?

Best Regards
Sarah
 

Postby Guest » Tue Jun 07, 2005 2:35 pm

Hi,

ORP is an abbreviation for for Oxidation Reduction Potential, also know as REDOX and is a useful measurement for monitoring and controlling chemical reactions, and monitoring water quality.

The site with the most specs for an ORP probe I could find is here:

http://www2.vernier.com/booklets/orp.pdf

I think it needs to be amplified in the same way as a pH electrode, and if I conected it to the BNC connector on DrDAQ it would work. But I am already using that connection for measuring pH. Hence the need to connect it through one of the external phone jack connections.

Thanks.
Guest
 

Postby Guest » Tue Jun 07, 2005 2:42 pm

Additional Orp Prode specifications I found:

HANNA "HI8615" Orp Probe

SPECIFICATION "HI8615"
RANGE 4-20 mA
RESOLUTION 0.01 mA
ACCURACY (@20°C/68°F) ± 0.02 mA
TYPICAL EMC DEVIATION ± 0.25 mA
CALIBRATION Offset: ± 2.2 mA; Slope: ± 0.5 mA
Offset: ± 100 mV; Slope: 90-110%
INPUT High Impedance 1012 Ohms
OUTPUT Isolated 4-20 mA
PROTECTION IP 65
POWER SUPPLY 15-30 VDC (not included)
LOAD 500 Ohms Maximum
ENVIRONMENT 0 to 50°C (32 to 122°F); max 95% RH non-condensing
DIMENSIONS 110 x 165 x 90mm (4.3 x 6.5 x 3.5")
WEIGHT 1 kg (2.2 lb.)
Guest
 

Postby Sarah » Thu Jun 09, 2005 9:39 am

Hi

Thank you for your post and the information.

The sensor that you give specifications for has an output range of 4-20mA. You could use a shunt resistor and measure across this, that way you could measure a voltage and connect to the Voltage input on the side of the DrDAQ. This way you would not need to amplify the signal, you would only need a shunt resistor.

Hope this helps

Best Regards
Sarah
 


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