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I'm having difficulty in deciding about implementing an amplifier and whether I need it at all for a strain gauge. I never dealt with such situation before and would be very glad to have your opinions.

I will have the following strain_gauges: http://bridgetest.com/wp-content/uploads/ST350-Operations-Manual-v2.2.pdf

Here what I found so far as an amplifier topology: http://www.linear.com/solutions/1183 In my case the output of the straingauge will be very low; in the order of 1mV.

But there is a possibility I might use this device: http://www.microstrain.com/wireless/v-link-200  Im not so familiar with terminology in datasheet much.

Do you think I would still need to implement the LT’s strain gauge amplifier if I buy this wireless device for these straingauges of 1mV level variation? I was wondering would noise be a problem at this signal level if I don't amplify.

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  • \$\begingroup\$ I'd suggest you definitely need the strain gauge amplifier. Your wireless solution is +/-150 mV full scale ...your signal is down in the weeds. \$\endgroup\$
    – Jack Creasey
    Commented Apr 1, 2017 at 3:00
  • \$\begingroup\$ +/-150 mV means the signal input variation should be minimum 150mV right? os is that the range and resolution issue? so better I use that LT's amplifier. But theres a simulation in their website which is different as: 100k resistor becomes 100ohm(maybe a mistake), supply becomes +-15V not single. Did you see that? Does the 100k set the gain of the amplifier in the schematic? thanks. \$\endgroup\$
    – floppy380
    Commented Apr 1, 2017 at 3:53
  • \$\begingroup\$ the wireless device unders specs it says: Differential: ±1.22 mV to ±156 mV DC (bridge completion factory-configurable) Single-ended: ±2.56 V dc, ±5.12 V dc, ±10.24 V DC, 0 to 5.12 V dc, 0 to 10,24 V dc im kind of confused \$\endgroup\$
    – floppy380
    Commented Apr 1, 2017 at 4:03

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The manual is here and quick start guide is here.

It appears that the full scale range is configurable using their software.
Minimum differential appears to be +/- 2 mV or maybe less.
ir IF this is correct and IF your strain gauge outputs about 1 mV max then the V-Link 200 should be all you need. A closer reading of the manual and a look at the software manual should clarify this.

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  • \$\begingroup\$ T the output of the straingauge will be very low; in the order of 1mV. if the cables are longer than 10 m, i was thinking noise would be an issue. does the straingauge sensor's two output differential(mirrored) voltages? \$\endgroup\$
    – floppy380
    Commented Apr 1, 2017 at 12:02
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    \$\begingroup\$ After we deal with the cable length will you tell us it's in a locked filing cabinet in the basement and related to a bypass the Vogons are building :-) ? ( HHGTTG ). Why not put us out of our suspense and give us the complete question? Adding information to the question is better than in comments. | Long cables and small signal levels are more noise prone. | Can you put the V-link near the gauge. Having the extra amplifier is liable to help rather than hinder. | The strain gauge bridge's output is a balanced differential signal. \$\endgroup\$
    – Russell McMahon ♦
    Commented Apr 1, 2017 at 15:56
  • \$\begingroup\$ I agree and I now opened a new question to make it clear:electronics.stackexchange.com/questions/296158/… I would be glad to hear your opinion as well. Thanks \$\endgroup\$
    – floppy380
    Commented Apr 1, 2017 at 20:57

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