switches - Can arduino be used as a switch?

Hello I have had zero luck with finding anything related to this problem. Lets take the most basic circuitry: switch that turns on the light

• The values on the sketch are not accurate, couldn't change the values

How can I "replace" the Switch with Arduino? Do I need Zener Diode to achieve that?

I want to use it to light up a 225V, 330Watts Lamp (I'm in Europe) that is used in my room.

Answer

If you use Arduino directly as a switch for AC supply then this is not going to work although it would cause a catastrophe because 225V across Arduino's pins are going to damage a lot.

So the solution is to use Isolation of two Arduino and the Lamp. Isolation can be done as @yogece said using a Relay and Relay driver.

Relay is kind of current operated switch i.e. if sufficient amount of current flows through Relay coil then a switch will be CLOSED otherwise remains OPENED. The current driven by a typical relay at its rated voltage is between 25mA to 70mA.

As the I/O pins of Arduino can provide maximum 40mA current (According to ATMEGA 328 Current Specifications) it is not a good idea that you directly connect it to a Relay and if you do so it may burn the Arduino. This is why you need a relay driver.

A very simple Relay driver can be made using a transistor. This article can help you understand very basic Relay driver www.jaycar.com/images_uploaded/relaydrv.pdf

Here is a typical circuit,

^{simulate this circuit – Schematic created using CircuitLab}