Why to use Relay when they are not required? Buy some relays, use the simplest method to work the circuit as "IanP" and "Alexan" sugested ,and Donate those relays to the guide. Striclty ask him to answer why to use a long way while you have a easier way out.? Actually project guides in India make students to make / bring new concepts and projects and get themselves involved and get new ideas. Actaully your guide wants to study how to use a relay. Help him. Cheers