Figure 4 D. Driver Switching for Lighting and Water Pump Control Figure 4 shows the relay driver design for lighting and water pump control integrated with the NODEMCU ESP8266 controller with an application interface schematic created using flutter. The Relay Driver functions as a breaker or connector for the flow of electric current which is controlled by providing a certain voltage and current to the coil. In this circuit, a DC relay is used with a coil voltage of 12 Volt DC and a current treated of about 20 — 30 milli Ampere. Therefore, in general we cannot directly connect the NodeMCU output to the relay because the current is not large enough. Therefore, it is necessary to use a driver as a current amplifier which is usually a transistor.