How to Make a Dual 5V Power Supply From USB

In this guide, I’ll show you how to build a dual +5V -5V power supply from a standard USB outlet.

The finished dual power supply circuit

Dual power supplies with a negative output taken from the positive output can be a little tricky. It’s not a matter of difficulty, but about the low availability of support for easier ways to do this kind of power supply.

So I’ll show you one of the easiest ways to make a dual power supply (also known as bipolar power supply) using a simple USB connection.

It is fair to mention, that this will be for low-power projects since the IC used for this is not capable of outputting much power.

How To Measure Water Tank Depth Using Ultrasonic Sensor

In this tutorial, you’ll learn how to use an ultrasonic sensor. Specifically, you’ll learn how to use the HC-SR04 module with an Arduino to measure the depth of a water tank.

An ultrasonic sensor is one of those things that some people don’t like getting into just because it sounds complex to use and understand. But the fact is, it’s one of the most accessible and fun accessories for those who like to dabble in microcontrollers.

HC-SR04 Ultrasonic Sensor Front

Cap Half Full #7 – Opamp basics and the 4000 series IC

In this episode, we talk about operational amplifiers (opamps) and the 4000 series IC that Øyvind has been writing a series of posts on. We also accidentally came across a funny error on Arrow's website 😅.

Repairing Electronics: Electronic Candle

When visiting my parents for Christmas, my dad showed me three electronic candles that did not work anymore. He told me he had changed batteries and showed me that they did not show any signs of life.

I tried to get them to work as well, but no luck.

It sounded like a really fun device to repair, so I took them back to my lab in Oslo to try to see if I could figure out what the problem was.

When repairing electronics, you always have to start with what the problem is. Here, the problem was that nothing happened when connecting the batteries and pressing the ON switch.

When thinking about this problem I came up with two theories:

  • A dead LED inside the candle
  • Bad connections between batteries and the candle circuit

How To Use a Multimeter – The Beginner’s Guide

A multimeter is a tool you’ll be using a lot when building electronics. For troubleshooting, testing batteries, and a variety of other tasks.

In this tutorial, you’ll learn how to use a multimeter to measure current, voltage, and resistance.

Illustration of multimeter

Build a Cool Christmas Tree Ornament in 5 minutes

Do you want to build something on your own for Christmas, but don’t have much time? Or no experience? Then this project is for you.

One of the easiest ways to make a Christmas circuit that looks cool when you don’t have much time is to use a color-changing LED.

A color-changing LED looks like a normal LED, but it has an integrated chip that controls the LED and automatically cycles through different colors.

Halloween Electronics Project: Jack-O-Lantern

In this Halloween electronics project, I’ll show you how to make a cool Jack-O-Lantern. I used a 3D-printed carved pumpkin, but a real one works just as well (or even better!).

The Jack-O-Lantern Halloween Project

The project is based around three normal LEDs that I control so that they look like a flickering flame. Since my “pumpkin” was very small, I used 3mm LEDs. For bigger pumpkins, I recommend using bigger and brighter LEDs. For example these ultra-bright orange LEDs.

The LEDs are connected in series with a resistor to the PWM pins on the Arduino so that I can control the brightness. And in the code, I change the brightness of each LED to a random value for every 50 milliseconds.

The result? Check out the video below:

MOSFET Gate Resistor

Do you need a MOSFET gate resistor? What value should it be? And should it go before or after the pulldown resistor?

If you’re a bit impatient and just want the answer, here it is:

It will most likely work without a gate resistor, but adding one can prevent some potential problems. And 1000 Ω will most likely work. See the circuit diagram below for connecting your MOSFET gate resistor (the Pull-down resistor is optional):

Mosfet gate resistor placement

How Does a 555 Timer Work?

The 555 timer works by using three 5 kΩ resistors to divide the supply voltage in three. Two comparators compare these voltages to the input voltage, then sets or resets a flip-flop accordingly.

Below is a diagram showing what the 555 timer looks like on the inside:

How does a 555 timer work on the inside

555 Timer Tutorial: How It Works and Useful Example Circuits

In this 555 Timer tutorial, you’ll learn how to use the 555 timer to do fun things.

One of the first things many do with it is to create a blinking light. But that’s just one simple example of the many things you can do with this chip. You can also control motors, create an alarm, create a musical instrument, and much more.

Why Are Electronics Books So Hard?

A few weeks ago, I went to the library with my wife. I checked out some of the electronics books they had, and something interesting dawned upon me… First, I have to say that I feel confident in my ability to build pretty much anything when it comes to electronics. I’ve designed microchips, I’ve designed

What Is a Voltage Regulator and What Does It Do?

A voltage regulator is a component that gives you a stable output voltage, no matter if the input voltage changes. It’s an integrated circuit (IC), usually with three or more pins.

Voltage regulator

A typical example of when you need a voltage regulator is if all you have is a 9V battery, but your device needs 5V. A voltage regulator can take those 9V as input and create a nice and stable 5V output that you can use to power your device.

Or if you need different voltage levels for a circuit you’re building. Let’s say you have a circuit with a microcontroller that needs 5V and a motor that needs 12V. Instead of using two power supplies, you can use just one 12V supply and add a voltage regulator to provide 5V for the microcontroller.

How To Edit Symbol in KiCad

I was recently asked how to edit a symbol in KiCad. The question was actually how to stretch a component that was in the standard library, so I made a quick walk-through on how to do that. You can edit the symbol in the symbol editor. Just right-click on the symbol that you want to

Me looking back at 5 years of Ohmify (it’s our birthday!)

5 years ago today, I launched Ohmify from my laptop while traveling in Colombia. I had spent the previous night in a tree hut on the beach to recharge my batteries. Now the moment had come… I was finally launching Ohmify! Something that I’d dreamed about for a long time. I created Ohmify to be

From Arduino Prototype to Manufacturable Product

The Arduino is an ideal platform for proving your product concept. However, there is still a lot of engineering work required to turn it into a product that can be manufactured and sold. The best way to progress from an Arduino prototype to a consumer product that is ready for sale is to use the