Øyvind Nydal Dahl

Øyvind Nydal Dahl is an electronics engineer and author from Norway. He holds a master's degree in electronics and computer technology from the University of Oslo, with microelectronics as his main field, and has been teaching electronics since 2012 through books, workshops, courses and articles. He's the founder of Build Electronic Circuits and the online electronics academy Ohmify, the creator of Circuit Canvas, and the author of Electronics For Kids and A Beginner's Guide to Circuits.

Portable USB Charger Circuit

Build this portable USB charger circuit, and you’ll always have access to a charger.

Imagine a beautiful summer day. You’re on your way to meet friends for a picnic in the park. But, the park is huge and full of people. Since you don’t know where exactly your friends are, you pick up your phone to call them.

But as you dial the number, the battery on your phone dies…

Ahhh!

With this portable USB charger circuit, there’s no need to worry. Just drop by a supermarket nearby and pick up some standard batteries to recharge your phone on-the-go.

PNP Transistor – How Does It Work?

The PNP transistor was a mystery to me for a long time. But when I at some point was forced to learn it, I realized that it was pretty simple. And if you want to design circuits with transistors, it’s really worth knowing about this type of transistor.

For example, want to automatically turn on a light when it gets dark? The PNP transistor will make this easy for you. Let’s dive in!

PNP transistor and symbol

In my article how transistors work, I explained how a standard NPN transistor works. If you haven’t already, I’d really urge you to read that article first.

If you understand the NPN transistor, it will make it easier to understand the PNP transistor. They work pretty much in the same way, with one major difference: The currents in the PNP transistor flow in the opposite directions of the currents in the NPN transistor.

Christmas Gift Ideas For The Electronics Hobbyist

red-christmas-presentsWhat do you buy for Christmas for someone who’s interested in electronics? Check out these Christmas gift ideas and get the shopping over with.

Last year I received three boxes with a lot of resistors and capacitors from my family. And I absolutely loved it!

I guess a box of resistors and capacitors isn’t everyone’s cup of tea…

Instead, here are some Christmas gift ideas from me that I think every electronics-interested kid, adult or grandparent would love.

Blinking Christmas Lights

blinking-christmas-lights-finished

Christmas is coming up, so why not set aside an hour or two to build this blinking Christmas lights circuit?

This circuit is easy to build and it’s something you can put to use right away. I built this and hung it in the window, something my girlfriend loved!

The blinking part of the circuit is made up of only 4 components. Then you’ll add as many lights as you want.

How To Choose a Power Supply

640px-wall-wart-ac-adapter-public-domainThere’s some confusion going on when it comes to how to choose a power supply.

So, I thought I’d clear up some doubts, and give you a simple, beginner-friendly way of choosing a power supply.

Let’s start with the basics. A power supply has a voltage and a current specification:

  • The voltage is the output voltage from the power supply.
  • The current is the maximum current that the power supply can give.

The Simplest Power Supply Circuit

power-supply-protoboard

This power supply circuit is easy to build and cheap. And it requires only 5 components.

I have built many circuits in my life, but this is actually the first time I’ve built a power supply circuit from scratch.

The final project I wanted to build was a wall adapter with a USB socket to charge my iPhone. But first I wanted to start by creating a simple circuit that converts from the main power voltage, 220V or 110V, to 5V.

As I’m in Australia while writing this, and the voltage here is 220V, I built this with 220V in mind. But it’s very easy to convert to 110V instead by switching one connection (or one component).

Who Else Wants To Develop Their Own Electronic Product?

Do you have an idea for an electronic product that you know will sell? Do you know how to create it?

Back in the days, my friends Olav and Elias and I were certain that we had a revolutionary product idea. We wanted to develop a touch-less controller for games, so that you could play games with your body as the controller.

We had learned a lot about circuit design at the University, but had very little practical experience. And we had never developed an electronic product before.

Our touch-less controller prototype
Our touch-less controller prototype

So many things could go wrong…

Your circuit doesn’t work? Here’s what to do…

components-on-breadboard

Do you have a circuit that doesn’t work?

Do you feel you’ve done everything you could? You’ve reconnected the circuit 100 times, and it still doesn’t work?

You’ve put in so much effort, but still no reward…

How does that feel? Are you starting to feel like building electronic circuits might not be for you?

Don’t worry, I’ve been there.

And I have the solution for you.

The solution is being smart. It’s by not giving in to the feeling of giving up or the feeling of trying to work harder.

I started out writing this for myself as a reminder for next time. But then I figured, hey – maybe more people could benefit from this.

Tips: Get started on any project, without buying a single component

resistor2Do you have an idea for an electronics project that you want to build? Are you stuck because you don’t know how to start?

Well, then this is for you…

Whenever I take on a new project that is very different from anything I’ve ever done before, this happens:

Let’s say I want to build an RC model airplane (which is something I’ve never done before). The first automatic reaction in my brain is “But I don’t even know where to start!!!”.

When I was more inexperienced I often gave in to this first reaction. So, I postponed the project.

“Maybe next month” I told myself.

What is BeagleBone?

BeagleBone Black on white backgroundThe BeagleBone is a mini computer, in the size of a credit card. Very similar to a Raspberry Pi.

You can connect a mouse, a keyboard and a display – and you’ll have a fully functional computer.

But most people don’t buy it to use as a normal computer…

…so, what is BeagleBone aside from this?

There’s much more exciting things to make from it… Like:

  • Arcade games
  • Advanced robots
  • Your own coffee machine (like Elias did)
  • Handheld gaming devices
  • Home automation systems
  • 3D printers
  • …and much more

Getting Started With Beaglebone Review

getting-started-with-beaglebone-book-coverI just finished reading Getting Started With Beaglebone by Matt Richardson.

I’m working on a coffee-related project where I need something more powerful than just the Arduino.

The BeagleBone with its HDMI-output and whatnot, is perfect! But I had only used it a little bit several years ago. So I needed a brush-up.

I didn’t want a “here is EVERY technical detail of the BeagleBone” type-of-book.

I know that I learn much faster if I start with an overview, then dig into details later on as I need them.

That’s why Getting Started With Beaglebone caught my eye.

BeagleBone Black Getting Started Guide

beaglebone

If you’re new to the BeagleBone, it can seem complex to get started. I’ve put together this BeagleBone Black getting started guide to help you over the first hurdle.

And as you’ll see, it’s really not that hard.

Confused? Check out What Is BeagleBone?

My intention with the BeagleBone Black now is to use it to develop electronics for a coffee-related project. With the BeagleBone, I can add a beautiful touch screen to the project, because it has HDMI output.

I have only barely tried the BeagleBone before, and that was a few years ago. So I’m writing this guide with a beginner’s mindset.

Resistor Color Code Calculator and Table (4 and 5-band)

The resistor color code (color bands) on your resistor tells you what value the resistor has. There are usually 4 or 5 bands. Use our simple resistor color code calculator tool below to easily find the value of any resistor.

Select resistor type:

The color bands on your resistor tells you what value the resistor has. Click on a color band below to change its color and the value and tolerance will automatically update to the correct value.

Value: 1000 Ω
Tolerance: 5 %

Experiment with the tool above by clicking on a color band to change its color. Then see the resulting value and tolerance. If you want to know what each color and resistor color band represents, check out the table below.

Resistor Color Codes Table

You can find the color bands and the values they represent in the table below:

Further down this page, you’ll find examples of how to use the color table.

Build The Knight Rider Light Bar Circuit With LEDs

The Knight Rider light bar circuit creates a running light similar to the light bar on the car from the television show Knight Rider.

It’s a really fun circuit to build. I once built a larger version of this for the inside of a party bus I was a part of. Unfortunately, I broke it the first day because I increased the voltage too much, but that’s another story.

You can build this circuit if you’re a total beginner, but of course, it’s a bit easier if you have already built a few circuits before.