This document provides an overview of biomedical instruments including electroencephalography (EEG), electrocardiography (ECG), and electromyography (EMG). It discusses the purpose and applications of each, and includes block diagrams of the components and systems. EEG measures electrical activity in the brain and is used to diagnose epilepsy and other brain disorders. ECG measures the heart's electrical activity through electrodes on the skin and is used to diagnose heart conditions. EMG measures muscle electrical activity and is used to diagnose neuromuscular diseases.