Developing a Force sensor

[Vikky]

Hi everyone,

I am in process of developing a force sensor with the range of +/- 20N. For this i have selected load cell as a sensor from Joint Sensor Instruments (szjoint.com).

The part i have selected is CZS - 101 which can uphold upto 50 lbs of weight. I want to have the circuit idea for getting the output from it. The o/p will be from 100mv - 1100 mv. (600 mv for 0 N).

Also i should have a calibration option so that the zero drift should be omited. Can anybody help me with the schematic and its functioning.

I suppose, i should have a differential amplifier with one terminal always at some reference mv and other tied to the mesauring sensor. The o/p range can be selected with proper gain. But what about calibrating for 0 lbs. If i keep a DAC which will adjust the o/p to 600 mv at 0 lbs with some count, then what should be done with these count value. Whether these count value should be added or subtracted from the final value???

 

[ericgibbs]

Hi everyone,

I am in process of developing a force sensor with the range of +/- 20N. For this i have selected load cell as a sensor from Joint Sensor Instruments (szjoint.com).

The part i have selected is CZS - 101 which can uphold upto 50 lbs of weight. I want to have the circuit idea for getting the output from it. The o/p will be from 100mv - 1100 mv. (600 mv for 0 N).

Also i should have a calibration option so that the zero drift should be omited. Can anybody help me with the schematic and its functioning.

I suppose, i should have a differential amplifier with one terminal always at some reference mv and other tied to the mesauring sensor. The o/p range can be selected with proper gain. But what about calibrating for 0 lbs. If i keep a DAC which will adjust the o/p to 600 mv at 0 lbs with some count, then what should be done with these count value. Whether these count value should be added or subtracted from the final value???

hi,
Look at this option, using a Instrumentation OPA.
In your text I think you mean ADC.?

With this circuit
-20N [100mV] will give a 0V out
0N [600mV] =+2.5V
+20N[1100mV]=+5V

If the Vout is input to a 16bit ADC , then
-20N = 0000h
0N = 8000h
+20N = FFFFh

EDIT:
Image #2 option, uses a standard OPA