Hello everyone,
I am a beginner in arduino, and electronics in general.
I need to amplify a 100mv signal to 0-5V or 0-10V that I can read with my arduino.
I have come across a previous post addressing the same issue here:
http://forum.arduino.cc/index.php?topic=205229.0
But I am not quite sure about which op amp to use, an instrumentation amplifier, or an operational amplifier?
I attached the datasheet of the sensor.
Thank you
Ali T.
XTEH-10L-190.pdf (95.7 KB)
alitarraf:
I need to amplify a 100mv signal to 0-5V or 0-10V that I can read with my arduino.
Arduino analog ports read 0-5V, so I would dismiss 0-10V.
Thanks for pointing that out.
I am open to any suggestions, even if it is to buy an off the shelf unit that will do the job.
My main concern is to minimize noise issues, and have a reasonable degree of accuracy.
Ali T.
How fast do you want to track changes in pressure?
I would like to have a minimum of 0.5-1Khz. I would like to use this sensor for static pressure measurement.
I am using other dynamic pressure sensors with Labview and specialized DAQ that can go up to 500Khz.
But if we can design the circuitry to be able to do 50Khz or 100Khz, that would be also great to have.
Thanks for asking.
Ali T.
Than INA125 is a way to go. Google data sheet.
For lower sampl. rate I thought you may use HX711.
I think the HX711 is unsuitable because of the lower supply voltage (<5volt).
The sensor is rated for 10volt, so the INA125 with it's 10volt reference would be a good match.
Supply the INA with 12volt regulated, IAref to ground, and a 1:1 voltage divider on the output.
Leo..
Wawa:
I think the HX711 is unsuitable because of the lower supply voltage (<5volt).The sensor is rated for 10volt, so the INA125 with it's 10volt reference would be a good match.
Supply the INA with 12volt regulated, IAref to ground, and a 1:1 voltage divider on the output.
Leo..
I find no indication that sensor has active components, probably it's just bridge 4- resistive strain gauges, same as load cell.
My understanding of "rated voltage" is the maximum voltage you may apply accounting dissipated power - accuracy loss due temperature change. Nothing prevents to apply low voltage, down to 1V or less.
The INA 125 seems suitable for a wide range of operation frequencies.
Is there any assembled circuit module for the INA 125, like the one available in the link "Magician" posted about the HX711 used for weighing scales?
If not, I will try to work out a circuit schematic with the INA 125 and have your feedback on it soon.
Thank you
Ali T.
Magician:
My understanding of "rated voltage" is the maximum voltage you may apply accounting dissipated power - accuracy loss due temperature change. Nothing prevents to apply low voltage, down to 1V or less.
That's what I also understand. The only thing that also will go down with supply voltage is output voltage.
I think the Sparkfun HX711 is set for 4.3volt bridge supply.
Sensor output will be 43mV max at that voltage.
That has to be weighed against the specs of the amplifier and A/D converters.
Leo..
That's what I also understand. The only thing that also will go down with supply voltage is output voltage.
I think the Sparkfun HX711 is set for 4.3volt bridge supply.
Sensor output will be 43mV max at that voltage.
That has to be weighed against the specs of the amplifier and A/D converters.
I agree, that useful signal level diminishing with lower supply voltage. But for low sampling rate , load cell needs only 1- 10 sps, it's not an issue, as 24-bits adc brings 16384x additional gain compare to arduino's 10-bits ADC. The problem may arise if required sampling rate > 1 msps, where high resolution ADC isn't accessible or cost too much.
Author wants 1 ksps, so Hx711 is not an option, but I'd look at ADS1115
or AD7705
IMHO, external ADC with internal PGA is better option, than design INA125 board + 10V power supply interface like they did in 80-x or 90-x, luckily price for such module is quite reasonable.
Guys,
I found this company who does an interesting board with the INA 125 and a butter-worth filter selling at around 40$ with shipping.
I am attaching the datasheet and a link to their website, please let me know your thoughts.
http://picom2.com/Phillips_Instruments.html
Thanks
Ali T.
INA125Manual_picom.pdf (920 KB)
In my opinion, board is obsolete. You will have to design another interface stage between board(+-12V) and arduino(+5V).
Doesn't make sense. I change my mind saying INA125 in the beginning (so INA122 - single supply 'd be better), to AD7705 or ADS1115 module, but external ADC brings better resolution, sooner or later you 'll realize that arduino's 10-bits is not enough
It is no problem to interface the output of an INA125 with Arduino's A/D.
A 2-resistor voltage divider is all you need.
Bad idea though to divide to the unstable default Aref.
Better to divide to ~1volt, and use 1.1volt Aref.
Still the problem of a 10-bit A/D, but the sensor might not be much better than that.
I think the HX711 board (Sparkfun) is the best, cheapest, and easiest solution here.
Leo..
Thanks for all the input guys.
Getting better resolution, and programmable gain is great. I actually found also a step by step tutorial on Adafruit on how to wire the ADS1115. This would work great as a start.
The only limitation is that the maximum data sampling rate is 860 samples/s.
What are my alternatives if I want to have a high speed data rate (lets say 50Khz) ?
My pressure sensor natural frequency is 700Khz, if I understand correctly this means that I can sample data (and still be safe) at about 20%, or 140 Khz.
I am not sure how complicated this would get, but would like to hear your thoughts about it.
Thanks
Ali t.
That can't be right. To say that you need to sample your pressure sensor at it's natural frequency doesn't make sense. It should not make any difference how often you sample it. If it is a pressure sensor , it outputs the pressure, period. Suggesting you need to sample it at 140khz sounds absurd. I didn't see anything on the datasheet that supports your suggestion. I would call the company and ask to speak to an Applications Engineer and ask him what sample frequency he recommends.
Let's keep in mind you said this:
I am a beginner in arduino, and electronics in general.
What are you measuring.
Gas, liquid.
That might be your limiting factor.
Leo..
Hi,
Are you going still use the kulite pressure sensor?
Are you aware that it is just a pressure load cell, you need exictation voltage in E+ and E- and you read a differential output from S+ and S-.
So you will need a differential AtoD to read it.
To get 100mV you are going to need 10V excitation.
There are AtoD that are designed for load cells applications HX711.
What is the application that requires such high sample rates?
Tom... 