Op amp applications:

• Inverting Amplifier
• Non-inverting Amplifier
• Buffer
• Summing Amplifier or Adder
• Subtractor or Differential Amplifier
• Comparator

Inverting amplifier: Can be used to multiply or divide, but the output voltage is inverted (or negative). Can be used to multiply by -1.

Non-inverting amplifier: Can be used to multiply. The output voltage is not inverted. Cannot be used to divide.

Buffer: It is a non-inverting amplifier with a gain of 1. It is used for impedance matching or current driving. The output voltage equals the input voltage.

Summing amplifier: It is used to add two or more input voltages. However, the output voltage is inverted or negative. You have to use an inverter (i.e. multiply by -1) to make the output voltage positive. It can also provide a different voltage gain to each of the input signals. By inverting one or more inputs to the summing amplifier, it can be used to add as well as subtract the input voltages.

Subtractor: Can be used to subtract two voltages. It can also provide a voltage gain at the same time.

Comparator: Used to compare two input voltages and tell which one is larger.

By using the six applications, we could use op amps to add, subtract, multiply, divide and compare various input voltages.

PBIL: Students will be give a simple mathematic equation and be asked to implement it using two or more op amp amplifiers.

An op amp is a very high gain direct coupled amplifier.

It can amplify both ac and dc signals.

Electrical characteristics:

• Very high voltage gain.
• Very high input impedance.
• Very low output impedance.

A good practical, readily available and cheap op amp IC is uA741 or LM741.

The photo above shows the internal circuitry of the IC uA741.