Biosignals are generally measured using three electrodes because we use an instrumentation amplifier: positive, negative and ground. Sometimes the negative input is connected to a group of electrodes instead to just one electrode, for example V1,...,V6.
The electrodes here are from Pulse Medical and are standard ECG electrodes with studs. The cables were made from snaps (which can be bought at Mandors). In the following clips we will use both the hand made and and the professional electrode clips.
After this general introduction we are going to show you step by step how to measure ECG and EEG: