Last Updated: 13/01/2024

#59 Arduino Project Wiring and Power supply

Projects >> #59 Arduino Project Wiring and Power supply

Wiring and Powering Arduino Projects.

It's Not Working! There's something wrong with the code!

Over the years I have helped a number of people with their Arduino projects and this is a cry I hear all the time. My standard response is "Have you checked your wiring?

I think in the region of 70% of all project problems have come down to poor or incorrect wiring so let's have a look at the boring subject of wiring.

The Breadboard

For a lot of people this is how they start building projects, a selection of solderless and duPont connectors and a breadboard with the poor old UNO powering the project through it's 5v Pin.

Breadboard and solderless connectors

One of the first changes to make is to add an external power supply.

Breadboard with external Power Supply

The reason for adding the external power supply is simple, Your Arduino is not a power station.

Power supply

Although an Arduino can power small projects it's not designed to power much at all. The follwong shows the power per pin and as a total for the board.

These figures keep the boards within safe limits. You can push them further but risk cooking your boards.

  Recomended Max Power Output per Pin Max Total Power Output
Arduino Uno 20mA (can be pushed to about 40mA) 500mA from USB, 800 from External Power Supply
Arduino Due 3-15mA 500mA from USB, 800 from External Power Supply
ESP32 Dev Module 20mA (can be pushed to about 40mA) 500mA from USB, 600mA from external Power supply

Component power requirements

  Power Draw
Servo (SG 90) 450mA
LED 10-15mA

As can be seen just adding 2 servos can easily push the board over it's limits.

So it's best to think of the Arduino as the signal generator, the brain of the project. The external power supply is the muscles of the project.

So for small breadboard projects start out by buying a small breadboard power supply and just plug in an old jack plug transformer of 7-12volts.

Building a permanent project.

Some people will try and pressure you into creating a circuit board and if you have a lot of boards to build that is the way to go.

However, for most of us we are building 1 off's so soldering components onto Vero Board or a prototype shield is probably the easiest way to start as you can copy your breadboad prototype.

There are a few types of veroboard so watch out. Some is individual holes, others the holes are on strips of copper as can be seen in the picture below.

Top right is an ESP32 project built onto veroboard, the ESP32 Dev Module plugs into some 2.54mm Headers in a similar way to the fitting of the shield bottom onto an Arduino UNO or Mega.

You will notice I use a variety of connectors that will feature in another article.

However, NOTE the ESP32 project top left. The blue screw connector on the top left of the board has a pin that has Red Nail varnish on it. I use this all the time to make the + of the power supply to the board. It's very hard wearing and cheap.


Project Boxes

Whatever the project you are building think about the environment it will run in.

How much vibration are you expecting.
Dust, dirt?

All these things are worth considering when you start to consider what sort of container the project needs to be in.

sometimes a box is not needed. I have an Arduino Mega based project that has a prototype shield and sits in a machines main control box. This provides enough protection even though that machine creates huge amounts of dust and it is often very cold.

Other projects need their own box.

Sometimes it's worth buying a decent project case.

as can be seen from the rear shot it also houses an ATX power supply to provide power no only for the boards but also for the item (a model railway) that the boards are controlling.

Project Case Front

Project Case Rear

This next project is a moel railway controller.
The container is 3D printed with the top cuot out of acrylic sheet.
It houses an ESP8266 D1 mini on vero board, Arduino Due with prototype shield with a ribbon connector to a 5.0" touch screen.
A 5v Power supply is provided through a USB C connector.

Control Panel front

Control Panel USB connector

Control Panel internals


When you are just passing a signal from the Arduino/ESP board you do not need thick wire, however what you do need is lots of colours.

A FREE way to get lots of coluored wires is to cut up old multi strand cables. VGA cables, old printer cables, it's amazing how many of these cables can produce loads of colours.

I slit the outer insulation and then just rip the inner cable through it.

I don't strip the whole cable in one go as it easily gets tangled so strip it back as I need it.

Striiping cables

Soldering Irons and Accessories

When it comes to sodlering irons you get what you pay for. However that doesn't mean you need to spend a lot of money.

You can get a cheap soldering iron kit for under £15 on Amazon/Ebay and if you are not going to use it a lot it will do the job.

I'm fortunate to have a very nice soldering/desoldering station but it cost about £150, however as it's in almost daily use it's been worth it.
However I still have a £15 special in the garage because soldeing stations are not easy to move about. So don't rush out and spend a fortune.

However some items you will need.

Soldering Iron holder: This solldering Iron comes with a very heavy holder, some are very light and flimsy. If your base is very light nail it to a piece of wood or something that will give it more stability. A hot solering iron falling in your lap is going to ruin your day.

Tip Cleaner: That golden bowl in the centre contains a tip cleaner, £5-6 on Ebay and worth every penny. Your soldering iron tip will last longer and be nicer to use.

Crocodile clip holder: These weighted multi hand stands are great for holding components while you solder them.... unless you have grown and extra arm.

Magnifier Headset: If like me your eyes can't see the small stuff get yourself a magnifier head set. Some even have lights. makes seeing things so much easier.

Good Lighting: Get youself some secent lights to see with. I have an LED rail above my workspace that I built that houses 12v LED cob lights.

Soldeing Station


For help or suggestions on new projects, please email the address in this image: and use #59 Arduino Project Wiring and Power supply as a reference.