Multi channel Instrumentation amplifiers breakout board or Hx711 with more input

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1

I need to get data from multiple load cells and strain gauges at once. Hz711 only one input(128 gain) so that means I need to use multiple Hx711.

Major requirements:

  • Multi channel (at least eight) single ended input
  • At least 128 gain factor
  • 80Hz or more sampling rate
  • at-least 16 bit ADC

So far I haven't found alternative to Hx711 that can take 8 or more inputs. That would be the best outcome.

The second best option would be to get ADC and amp. In the ADC front (no Instrumentation amplifiers), I found:

which suits my needs. But it doesn't have Instrumentation amplifiers. I was wondering if there was any breakout boards for the Instrumentation amplifiers only.

Regards,

2

Reading 8 load cells at 80 hz , with 16bit resolution will produce a lot of data - that might be a bottleneck.

What is the project ?

There are instrumentation amplifiers out there , google will find them . Wonder if multiplexing the load cells would do it ?

3

Are the load cells all measuring the same thing or different things?

4

They are measuring different forces though the body is same like

x-direction force on point 1
x-direction force on point 2
z-direction force on point 1

5

hammy:
Reading 8 load cells at 80 hz , with 16bit resolution will produce a lot of data - that might be a bottleneck.

What is the project ?

Oh yeah it might be and I forgot to take that into account. Thank you for reminding me. But if it becomes a bottleneck, I am willing to reduce the sampling frequency to some extent or even use two arduino. There is only one load cell signal which is used for control. Others are for taking readings only. So I can use say 2-3 arduino and seperate ADC.

It's a college project for testing stresses in structure.

hammy:
Reading 8 load cells at 80 hz , with 16bit resolution will produce a lot of data - that might be a bottleneck.

There are instrumentation amplifiers out there , google will find them . Wonder if multiplexing the load cells would do it ?

Umm I didn't quite understand this section of your reply. I am new to this and all I could find is single channel instumentation amps not say 4-8 channels. I know it is just joining them together but I was wondering if there is something already out there.

6

I have found AD7794 which has 6 channel, 24 bit ADC with on-chip gain of 128.

I am new to electronics and I have few questions that I would like to clear up. I hope you guys can help me out on this.

  • If I use in-Amp with 128 gain, I know that conditioned signal will be in ADC input signal range. (20mV*128 = 2.56V) But is there any minimum cut off range for the in-amp?

  • The AVDD = 2.7V to 5.25V. So as long as I supply voltage within that range, I will be okay?

  • It is possible that the external voltage (say 5V excitation) that I supply has some variation. If we look in say INA 125, it mentions about 10V, 5V, 2.5V regulator. But I don't seem to find such feature in AD7794. However there is 1.17V reference which I don't know what it is used for. So I need to add separate voltage reference for excitation?

Electronics is entirely new field for me. I have looked through data sheet but yeah I can't understand lots of things even googling the terms. I hope you can help me solve those confusions.