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I took apart a weighing scale to get the load cell from it. The weight scale was capable of measuring up to 85 pounds with 5 grams precision. The voltage drop of the weight scale, however, is too small. It is about 0.4 to 1.5 millivolts. I need to read this somehow. I tried amplifying it with op-amps and did not work. I read about high resolution ADC like HX 711. What would the simplest way for reading and feeding the signal from the load cell to microcontroller without compromising the accuracy or precision?

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    \$\begingroup\$ The usual way is to use an 'instrumentation amplifier' which you can build up out of 2 or 3 opamps or use a read-made one. TI, Linear tech, Analog Deviecs, etc all make many, many options. That'll give you a reasonable signal which you can feed to the ADC of your choice. \$\endgroup\$ – brhans Jan 26 '15 at 15:57
  • \$\begingroup\$ Something like the INA125 is a common choice for load cells in hobbyist applications. \$\endgroup\$ – whatsisname Jan 26 '15 at 16:14
  • \$\begingroup\$ From the weight and resolution that you specified the A/D converter in the original unit appears to have been good to 8192 counts. \$\endgroup\$ – Michael Karas Jan 26 '15 at 16:50
  • \$\begingroup\$ Have you considered to try to hack some of the amplifier and signal conditioning circuitry from the original unit? \$\endgroup\$ – Michael Karas Jan 26 '15 at 16:51
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The ADC that most of hobbyist use for Load cell is ADS1130. This is an 18 bit ADC with internal gain of 64 which transmits the converted bits serially. It would be easy to answer if you had mentioned the model of your microcontroller, because some of the microcontroller has amplifier embedded in it with high resolution bits of adc like Atmega16.

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