Strain gauge measurement circuit ads1248

Hi Aamir,

You could use the circuit you provided.  You could even simplify the measurement and make the strain guage connections similar to an RTD measurement using current excitation (by removing R1, R3 and R4 and connect R2 to R5 in series).  You need to consider the effect of self heating in this case, so you may want to reduce the current.  You can make the measurement ratiometric by using the voltage developed across R5 as the reference voltage.  In this way the strain  guage resistance is a ratio relative to the value of R5.

Best regards,

Bob B

I will use bridge circuit as might be I have to place dummy gauge for temperature compensation.

One problem: I have placed filter R6,R7,C1,c2 & C3 for filter. Since my circuit is battery powered so what I will do is pass current , take reading & then disconnect the current.

1. In this case, curent is on for very short time & filter capacitors also have to get charged to voltage produce. will it be a problem.

2. I have to use internal IDAC. Setting in register "MUX1", can I use "VREFCON1:0 = 11", so that current consumption can be reduced.

Hi Aamir,

You always need to consider the effects of analog filter settling.  You need to allow enough time for the filter to settle to 1/2 LSB of the conversion ability of the measurement.  You also need to consider the effect of reference settling as well.

So you need to take into account the time for analog settling in your overall power calculations.

Best regards,

Bob B