Bulk Metal® Foil vs Thin Film used in scale circuits measuring the weight of gold [TXCC+VPG #36]

Can precision resistors affect the price of gold? This video demonstration compares the accuracy of load cell weighing scales using Bulk Metal® Foil resistors versus thin film resistors (in an Intersil Instrumentation amplifier operated at 25⁰C and 60⁰C). Precision amplifiers depend upon the ratio of input and feedback resistors to set the circuit accuracy and common mode rejection ratio. Changes in the ratio of the resistors constitute a direct unattenuated error at the output. TCR mismatch is the first and most direct cause of ratio change. This demo uses a load cell with an Intersil ISL28617 low-noise precision instrument amplifier to weigh gold at 25⁰C and 60⁰C. With thin film resistors around the amplifier there is a significant and costly loss as a result of TCR mismatch, while the Bulk Metal® Foil resistors showed no change nor loss.