Tutorial: Op-amp circuit for force sensor signal conditioning

TL;DR

Learn how to create a circuit using an op-amp to measure the conductance of a force sensor and interface it with a microcontroller.

Transcript

hey everyone in this video I'm going to show you a circuit that you can use to interface this force sensor with a microcontroller or some other analog input device so this is a flexi force a 4:01 force sensor and it's a sort of like a variable resistor so let me zoom in and show you how to how to make this circuit okay so this force sensor is built... Read More

Key Insights

• 🪡 The force sensor has a non-linear resistance curve, and a circuit is needed to compensate for this to obtain accurate force measurements.
• 💄 The conductance of the force sensor is linearly related to the applied force, making it a suitable parameter to measure.
• 🍾 An op-amp circuit with a feedback resistor is used to measure the conductance of the force sensor.
• 🍾 The circuit requires a negative voltage supply for the op-amp, which can be generated using a self-contained DC to DC converter.
• 😘 Low-pass filters can be added to the circuit to filter out unwanted AC noise.
• 🍾 The LM324 op-amp is used in the circuit due to its ability to provide a 0 to 5-volt output range and availability in various packages.

Questions & Answers

Q: How does the resistance of the force sensor change with applied force?

The resistance of the force sensor decreases when force is applied, forming a curve that is non-linear.

Q: How does the circuit compensate for the non-linear curve of the force sensor?

The circuit uses the conductance of the force sensor, which is the reciprocal of resistance, to get a linear relationship with the applied force.

Q: What is the purpose of using an op-amp in the circuit?

The op-amp is used as a non-inverting amplifier to measure the conductance of the force sensor. It amplifies the signal and provides a linear output.

Q: How is the negative voltage supply for the op-amp generated?

A self-contained DC to DC converter is used to generate a negative 5-volt supply for the op-amp.

Summary & Key Takeaways

• The video explains how to create a circuit using an op-amp to interface a force sensor with a microcontroller or analog input device.

• The force sensor is a flexi force sensor with a variable resistance that changes with applied force.

• The video demonstrates how to compensate for the non-linear resistance curve of the force sensor to obtain meaningful force measurements.

• The circuit uses an op-amp and a feedback resistor to measure the conductance of the force sensor, which is linearly related to the applied force.