ECG Circuit With Arduino Plotting

This is an ECG built on a breadboard composed of 3 main filter sections. The sections include an instrumentation amplifier to amplify the electrical signal of the heart, a low pass filter to reduce noise, and a notch filter to eliminate power line interference. This circuit will be attached to an Arduino so that the ECG can be plotted. The purpose of this circuit is to create a small-scale ECG to read the electrical signal of the heart.

• 1 breadboard
• 5 op-amps
• 1 Arduino with USB cable
• 1 Laptop with Arduino software
• 3 electrodes
• A set of electrical wires
• Resistors: 3 x 2kOhm, 2 x 49kOhm, 2 x 40kOhm, 2 x 1.6kOhm, 2 x 1kOhm, 1 x 236kOhm
• Capacitors: 3 x 470nF, 4 x 168nF
• 2 9V batteries

Using the attached image of a circuit diagram as a frame of reference, use the given supplies to build this circuit.

1. Place down 3 op-amps about 5 lines apart from each other along the central split of the breadboard, (in order from closest to edge of the breadboard to farthest, referred to as op-amp 1, op-amp 2, op-amp 3).
2. Attach the electrodes to the input of op-amp 1.
3. Attach wires to each side of both 9V batteries.
4. Use the rails of the breadboard to create a positive and negative 9V supply voltage by attaching the positive end of a battery to a rail and the negative end of that battery to ground, while attaching the negative end of a different battery to a different rail and the positive end of that battery to ground.
5. Attach wires from the supply voltage rails to the respective supply voltage inputs of all 3 op-amps.
6. Attach a wire from V+ of op-amp 2 to ground.
7. Attach a 2kOhm resistor from V- of op-amp 1 to V- of op-amp 2.
8. Attach a 49kOhm resistor from V- of op-amp 1 to Vout of op-amp 1.
9. Attach a 49kOhm resistor from V- of op-amp 2 to Vout of op-amp 2.
10. Attach a 2kOhm resistor from Vout of op-amp 1 to V+ of op-amp 3.
11. Attach a 2kOhm resistor from Vout of op-amp 2 to V- of op-amp 3.
12. Attach a 40kOhm resistor from V+ of op-amp 3 to ground.
13. Attach a 40kOhm resistor from V- of op-amp 3 to Vout of op-amp 3.
14. Attach a wire to Vout to be used in the next step.

Using the attached image of a circuit diagram as a frame of reference, use the given supplies to build this circuit.

1. Place down 1 op-amp about 5 lines past op-amp 3 from Step 1 along the central split of the breadboard, (referred to as op-amp 4).
2. Attach wires from the supply voltage rails to the respective supply voltage inputs of op-amp 4.
3. Attach the wire from the end of Step 1 in series with a 1.6kOhm resistor.
4. Attach the resistor in series with a 1.6kOhm resistor that connects to V+ of op-amp 4.
5. Attach a 470nF capacitor from V+ of op-amp 4 to ground.
6. Attach two 470nF capacitors in parallel, then attach them from the 1.6kOhm - 1.6kOhm connection point to Vout of op-amp 4.
7. Attach V- of op-amp 4 to Vout of op-amp 4.
8. Attach a wire to Vout to be used in the next step.

Using the attached image of a circuit diagram as a frame of reference, use the given supplies to build this circuit.

1. Place down 1 op-amp about 5 lines past op-amp 4 from Step 2 along the central split of the breadboard, (referred to as op-amp 5).
2. Attach wires from the supply voltage rails to the respective supply voltage inputs of op-amp 5.
3. Attach the wire from the end of Step 2 in series with a 1kOhm resistor.
4. Attach the resistor in series with a 236kOhm resistor that connects to V+ of op-amp 5.
5. Attach two 168nF capacitors in parallel, then attach them from the 1kOhm - 236kOhm connection point to ground.
6. Attach a 168nF capacitor to the Step 2 wire - 1kOhm connection point.
7. Attach a 168 nF capacitor to V+ of op-amp 5 and attach it in series with the 168nF capacitor that is attached to the Step 2 wire - 1kOhm connection point.
8. Attach a 1kOhm resistor from the 168nF - 168nF connection point to Vout of op-amp 5.
9. Attach V- of op-amp 5 to Vout of op-amp 5.
10. Attach a wire to Vout to be used in the next step.

The combined circuit is now complete.

1. Install proper Arduino software on laptop.
2. Connect Arduino to laptop using USB cable.
3. Attach the wire from the end of Step 3 to a slot in the Arduino.
4. Attach a wire from a different slot in the Arduino to ground.
5. Attach one electrode to each wrist to measure the electrical signal of the heart.
6. Attach one electrode to either ankle to act as ground.
7. Code a plotting system in Arduino software to properly display the signal.
8. Begin measurement and watch the ECG as it is plotted on the laptop.

The combined circuit with Arduino is now complete.