A A researcher is using a tiny sensor mounted on a cockroach

A) A researcher is using a tiny sensor mounted on a cockroach to measure the roach’s body temperature. The voltage from the sensor is very small (microvolts). She amplifies the sensor\'s signal using an ordinary inverting op amp. She finds that the output signal is contaminated by hum and other noise. What op amp circuit can she use instead of the inverting circuit to eliminate much of the noise?

B) The researcher finds that the noise has been reduced using the new circuit, but that it is still unacceptably high. She has hooked up the microphone to the op amp circuit using two ordinary copper wires. Name two alternative wiring choices she has that might help eliminate the noise.

Solution

A). Hum is caused by interference from AC power supplies,fluorescent lights, and other things with AC power in them. Here she used single wire as a input to the inverting amplifier and which is contaminated by noise. Instead if she used differential configuration of opamp, then as noise comes on the both wire and they get cancelled out because of differential structure of an opamp.

B).If the lines between the temperature sensor and the Op Amp are unshielded then also it will add the noises. if proper sheilding mechanism is used then aluminum, and ferrous materials as appropriate for the environment.