Hello,
I'm building a handheld 5Kg weigh scale and have ordered a sample of sensors and am a little new to this. Attached is the datasheet.
With ~5.09V to the sensor I've measured the following differential output. This does not appear as stated in the datasheet. The range should have been @0g a range of 0.29mV - 0.31mV and @5000g a range of 9.8065mV - 11.2535mV.
Recorded Data:
Sensor 1 @ 0g = 5.315460mV
Sensor 1 @ 5000g = 17.226600mV
Sensor 2@ 0g = 3.575580mV
Sensor 2@ 5000g = 15.388600mV
Sensor 3 @ 0g = 0.685243mV
Sensor 3 @ 5000g = 12.290700mV
Sensor 4 @ 0g = 6.298300mV
Sensor 4 @ 5000g = 18.079000mV
How can I compensate for this range, especially the offset? I have been using the INA126 and a gain of 277 would allow me to measure the 18mV Sensor 4 on a 10bit ADC at 5V. However, this limits my range to 1.75V-5V. I would obviously like to realize the full 0-5V of the 10bit ADC.
Is there a potential design that allows me to build once, or does the board need to be customized for each sensor? I am also unsure how to trim the offset using the OPA237.
Regards,
Fraser
I'm building a handheld 5Kg weigh scale and have ordered a sample of sensors and am a little new to this. Attached is the datasheet.
With ~5.09V to the sensor I've measured the following differential output. This does not appear as stated in the datasheet. The range should have been @0g a range of 0.29mV - 0.31mV and @5000g a range of 9.8065mV - 11.2535mV.
Recorded Data:
Sensor 1 @ 0g = 5.315460mV
Sensor 1 @ 5000g = 17.226600mV
Sensor 2@ 0g = 3.575580mV
Sensor 2@ 5000g = 15.388600mV
Sensor 3 @ 0g = 0.685243mV
Sensor 3 @ 5000g = 12.290700mV
Sensor 4 @ 0g = 6.298300mV
Sensor 4 @ 5000g = 18.079000mV
How can I compensate for this range, especially the offset? I have been using the INA126 and a gain of 277 would allow me to measure the 18mV Sensor 4 on a 10bit ADC at 5V. However, this limits my range to 1.75V-5V. I would obviously like to realize the full 0-5V of the 10bit ADC.
Is there a potential design that allows me to build once, or does the board need to be customized for each sensor? I am also unsure how to trim the offset using the OPA237.
Regards,
Fraser
Attachments
-
103 KB Views: 16