Automatic lighting system

Imagine a world where all you have to do to get the lights on, is to just set a timer on. Like an alarm and it’ll be on at the stated time. That easy. No switches at all required. How? You ask. Well, using any Arduino board, a relay and your lamp. These are the basic components you require .

The article below covers the design of the automatic lighting system project right from circuit design to the testing phase.

What you need?

• Arduino board (any) : Uno, Mega, Nano, Pro Mini, etc

• USB cable for programming the Arduino board

• 5V relay module

• BC547 NPN transistor

• 1kOhm resistor

• 1n4007 Diode

• Some male/female header pins

• Some male/female connectors

• 2-pin 5mm screw terminal

• Coper clad board for etching your PCB

• Solder gun

• Solder wire

• And your AC bulb!

For software you need the Arduino IDE and KiCad for designing the PCB

PCB design

KiCad is a very remarkable tool for printed circuit board design bringing design automations, design analysis and a 3d view of a PCB , on the fly! First create a schematic of your circuit using components from the symbol library. Once you have found all the components required from the symbol library, the next step is to wire the components as per your circuit. Lastly, you need to select a PCB footprint for all the components in your schematic.

   Now you can start the PCB design. This requires you to define your PCB size and shape, place schematic components on the PCB, and make wiring between components. Be sure to avoid overlapping components and wiring! Once you’re done with wiring, you can add a print of your name or project version, on either side of the PCB. So yes, you can name your circuit board, Mr. Wiggle Board if it pleases you.

PCB Fabrication (etching)

Print the circuit design, or should I say print Mr. Wiggle Board onto glossy paper, using KiCad PCB export to PDF. Take a copper clad board and first clean it to remove dirt! Then slap your glossy paper on the copper board and use some tape to hold it in position.

You can use your clothes, a dry or steam iron to transfer all the print to copper board. Next remove the print from copper board and etch the board with a solution like ferric chloride. Until all copper that’s not covered with print is removed. Afterwards rinse the board with water, inspect and remove the print layer using alcohol such as ethanol.

Use a hand-held drill for the holes on the PCB, where you’ll mount your electronic parts.

Soldering of components

This was my favorite part. Getting to give your project legs, hands and very crucial functional parts. Mounting the Led, male/female header, capacitors, diode, relay and resistors using a solder wire and gun. Great caution should be taken here as one would not want to short circuit the Board!

Smoke Test

This was one of the most terrifying stages! Connecting your Arduino to the PCB pins and the lamp and mains (220V) power to the PCB.

 As soon as the circuit was powered, the bulb that we used did not first turn on as required. But at least no smoke was seen or the PCB exploding. This required troubleshooting the PCB connection and also Arduino code to determine where Mr. Wiggle saw the problem .

And then finally, Mr. Wiggle blinked after a reset time of 10 seconds or whatever time we changed it to.