OPERATIONAL AMPLIFIER (LM 741)

Figure 1: Datasheet of LM 741

      An operational amplifier (op-amp) is a DC-coupled high-gain electronic voltage amplifier with a differential input and, usually, a single-ended output. An opamp produces an output voltage that is typically hundreds of thousands times larger than the voltage difference between its input terminals.

The circuit symbol for an op-amp is shown to the right, where:

• ·         V+ : Non-inverting input
• ·         V- : Inverting input
• ·         V_out : Output
• ·         V_S+ : +12V positive power supply
• ·         V_S- : -12V negative power supply

By using non inverting circuit, this op-amp will amplified higher signal input that came from the voltage of heart beat to the circuit voltage comparator to get the output.

Figure 2: Op amp 741 with Non-inverting amplifier circuit