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Øyvind Nydal Dahl

Øyvind Nydal Dahl is an author, maker, and electronics enthusiast from Norway. He holds a master's degree in electronics from the University of Oslo and have been teaching electronics since 2012 through books, workshops, courses and articles. He's the founder of the online electronics academy Ohmify. And he's the author of Electronics For Kids and A Beginner's Guide To Circuits.

What Is Electric Current?

Electric current is what you get when electric charge moves around a circuit. It’s pretty simple when you finally get it. But there are some common pitfalls that can give you the wrong idea when learning.

And if you don’t know what current is and how it works, it’s a huge source of confusion when learning electronics.

Ohms law cartoon showing that electric current flows.

My goal is that after reading this article, you’ll understand what current is. And you’ll understand that a resistor must have the same amount of current going into it as going out from it.

How to Build an Arduino Theremin

In this short tutorial, you will learn how to build an Arduino Theremin. You only need three components plus the Arduino, wires, and breadboard.

Use the breadboard diagram or the video below to see how to connect everything.

AC vs DC: The difference between alternating and direct current

The difference between Alternating Current (AC) and Direct Current (DC) is simple: AC vs DC comes down to how the current flows. AC is a current that alternates its direction. It goes back and forth continuously. DC is a current that flows in one direction.

Current flow in a DC circuit:

Animated gif that shows the flow of current in a DC circuit

For example, a battery provides direct current. The current only flows one way out of a battery.

Simple VU-Meter Circuit

A VU meter on a breadboard

I put together this Voltage Unit (VU) meter using LEDs on a breadboard the other day. It only has 4 LEDs, but can easily be expanded to more:

It’s basically a simple display for showing a value. It’s originally for showing signal level in audio circuits, but there’s no reason you can’t use it to show temperature, rain intensity, light level, or whatever other value you are measuring.

What is Negative Voltage?

Batteries connected to acheive negative voltage

I’m going to show you what negative voltage is by putting John into a hole. As you’ll quickly learn, it’s nothing weird or mystical.

Meet John. He is 1.8 meters (6 feet) tall.

What does it mean that John is 1.8 m tall? Could you find his height by only looking at his head?

No. You have to compare the top of his head to the ground he is standing on to be able to find his height. That John is 1.8 m tall really means that the top of his head is 1.8 m higher than the ground that he stands on.

It’s the same thing with voltage. You can’t say anything about the voltage without comparing it to another point.

Why does the battery voltage change?

Today I got a question from Garry on the Ohmify community.

[GARRY]:
“When I measure the voltage of my 9V battery using my multimeter I get a reading of 9.06 when it is not connected to any circuit. When I hook the battery up to a simple circuit (i.e. 325 Ohm resistor in series with a red LED) and measure the voltage drop across the battery I get a reading of 8.65 V – why the difference?”

Build Instructions: The Blinking Light Circuit

LED on a breadboard

Do you want to build a circuit that blinks a light? This inverter-based circuit is simple, and it’s small enough to fit on a breadboard.

The circuit uses standard basic electronic components and you can build it even if you have never built anything before. Check out the full build instructions in the video below:


Scroll down to find the complete circuit diagram, component list, and step-by-step instructions (in text-form) on how to build this circuit.

Sewable circuits and kebabs in Berlin [VIDEO]

oyvind dahl standing by the berlin subway

I went to Berlin with Elias Bakken. It’s such a cool city.

We met up with Helen Leigh and Drew Fustini to eat kebabs, see homemade instruments, play artsy video games and learn about sewable circuits.

Check out the video below!

How can I learn to repair electronics?

Loose wire from motor

One of the things that I love about being able to build electronics is that I can also REPAIR electronics =)

Repairing electronics for my drone

I often get the question:

“How can I learn to repair electronics?”

My response is:

Notes on current flow for email lesson 4

These notes are from Lesson 4 of my Free Email Course. Do you know anyone else who would love to learn electronics? Please share that link with them.

Below you can see the circuit we’re currently talking about.

The resistor and capacitor on the left of the inverter make up an RC delay element:

But how does the current flow in this circuit?

The RC Delay Element

RC delay element

The RC delay element is a way to create a time delay in your circuit by connecting a resistor and a capacitor. It’s super simple. And very useful.

The ‘R’ is a resistor, and the ‘C’ is a capacitor. That’s where the ‘RC’ comes from. And here’s how you connect the two:

RC delay element explanation