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Why do you need a relay Arduino?
To control high-voltage or high-power circuits with an Arduino, you have to isolate them from the Arduino with a relay. A relay consists of an electromagnet that, when energized, causes a switch to close or open. Relays provide complete electrical isolation between the control circuit and the circuit being controlled.
Do you need a relay in a circuit?
One of the most common situations that require the use of a relay occurs when an application needs to switch from high to low current (or vice versa) within the same circuit. For example, the temperature sensors that power HVAC units require levels of amperage that vastly exceed the capacity of their wiring.
What can you do with an Arduino relay?
It is used to programmatically control on/off the devices, which use the high voltage and/or high current. It is a bridge between Arduino and high voltage devices. When you are making projects that are connected to mains voltage, you need to know what you are doing, otherwise, you may shock yourself.
Can a micro controller be used to control a relay?
A micro controller’s GPIO (general purpose input/output) pins cannot handle higher power devices. A LED is easy enough, but large power items such as light bulbs, motors, pumps or fans required more sneaky circuitry. You can use a 5V relay to switch the 120-240V current and use the Arduino to control the relay.
Do you need a transistor to drive a relay?
The coil of the relay needs a large current (around 150mA) to drive the relay, which an Arduino cannot provide. Therefore we need a device to amplify the current. In this project the NPN transistor 2N2222 drives the relay when the NPN junction gets saturated.
Can a light bulb be connected to an Arduino?
For the light bulb, we MUST use another power source (high voltage and/or high current), which can burn Arduino. Therefore, we CANNOT connect the light bulb directly to Arduino’s pin. We need to use a relay between Arduino’s pin and light bulb to protect Arduino from high voltage/current. Please note: These are affiliate links.