Hello friends! Today, we will study relay control using a 555 timer in Proteus ISIS. A relay allows a small control circuit to operate a separate load circuit, and a timer adds a useful extra function: keeping that load on for a selected interval. We will work with a low-voltage DC motor so that the control sequence is easy to observe. Before connecting the components, we need to distinguish manual switching from timed switching. The original project contains a button in the relay-coil path, but that arrangement does not by itself create a timed output. We will first read the original drawing, then develop a monostable circuit whose behavior can be calculated. By the end, you should understand the relay contacts, the transistor interface, the protection diode and the relationship between t ...