Overview of the INA2126 Amplifier

The INA2126 is the model of the amplifier that we will be using for this project. The two amplifiers in the INA2126 are capable of producing signals ranging from -9V to +9V using 9V batteries. The INA2126 can be set to a gain between 5 and 10,000. Using the EOG software, however, we only need to set the gain to 1500 in order to give us a signal with a range between about -1.5V and +1.5V since readings over 30 degrees of movement are not as accurate. The gain was found using the equation:
                                                  A=VO/V_EMG 
where A is the gain, VO is the output voltage, and V_EMG is the original voltage before amplification (.0005V-.002V according to research). This means that when the input is 100 µV into the amplifier, the output will be .15V, which will then be recorded using the MATLAB software [4]. Using the following equation:

we were able to find that the resistor value for our gain of 2000 is 53.5Ω [4]. The full data sheet for the INA2126 amplifier can be accessed here. Another instrument we will be using is the DAQ model NI USB-6009 or Data Acquisition Device which will change the signal from the amplifier into one that the MATLAB computer system is capable of reading and working with. The input signal in the DAQ cannot be too small due to its low accuracy at small voltages. The DAQ has an accuracy of +/- 14.7 mV meaning that the input is rounded if it is too small and can then tamper with our results. Therefore, with a output voltage of 1.5V from the amplifier and a multiple of 14.7 mV in the DAQ, we are given a resolution of about 102 multiples. This should still give us an accurate reading of the signal in MATLAB.

Figure 7: INA2126 Amplifier [4]