A couple of weeks ago I wrote about four current flow direction myths. As a follow up to that popular post, I decided to dedicate this month’s AddOhms electronics tutorial video to Current Flow. In episode #19, I tackle the question of which way does current flow.
You might have heard about “conventional flow” and “electron flow.” In conventional flow, we assume that current flows from the positive voltage towards the negative voltage. In digital, the “negative voltage” is usually called ground. However, that’s not how the electrons move nor is it how they carry the charge around a circuit path.
Electron flow is the description of how electrons carry a charge. Which is the negative voltage towards the positive? This confusion is a result of Ben Franklin mistakingly identifying how electrons moved so many years ago. Yet, we have kept the “positive” and “negative” labels as they are today.
The key though is that it doesn’t matter which method you use to analyze a circuit. Electrons move in a closed path. So whether they travel from positive to negative or from negative to positive, doesn’t matter!
AddOhms #19: Current Flow Direction
Almost all microcontroller (and microprocessor) development systems use some form of a bootloader. Often called firmware, mistakenly, the Arduino bootloader is one example. Since it is a rather popular platform, let’s use it as an example. Let’s talk about what a bootloader does and how it works.
When a microcontroller turns on, it only knows how to do one thing. Typically, that one thing is to run an instruction found at a specific memory location. Often this location address 0x0000, but not always. Usually, this memory location will contain a jump instruction to another place in memory, which is the start of the user program. The bootloader, however, exists in a slightly separate memory space from the user program.
On power-up or reset, a bootloader is a section of program memory that runs before the main code runs. It can be used to setup the microcontroller or provide limited ability to update the main program’s code.
A KiCad BOM is a list of all the parts your design is using. The term BOM, or bill-of-materials, is standard for supply chain management and does not just apply to electronics. KiCad’s eeschema has a BOM export feature. Unfortunately as of Version 4.0, this feature is still somewhat lacking. Given the limitations, here are some tips to take your KiCad BOM from Schematic to Mouser.
Spending a few extra minutes while capturing (drawing) your schematic thinking about your KiCad BOM can save you a ton of time later on. Moreover, as you build up a database of parts, these extra minutes turn into seconds. Here are a couple of ways to describe your parts, especially passive components, better while drawing schematics in KiCad.
I was invited to speak at the 11th Hardware Developers Didactic Galactic group at the Supplyframe office in San Francisco. I talked about the misconception that capacitors are a simple device.
Chris Gammell recorded the discussion and posted it via PHY Media. This video is about 50 minutes.
In this talk, I break down a few things to know about Ceramic, Aluminum, Tantalum, and Supercapacitors. You can see the full video via PHY Media’s YouTube Channel: They’re JUST Capacitors. For links and the slides, check out this post.
Electronic safety tips from mountain climbing? Yes! After spending two weeks in Europe for work, I had the chance to spend a weekend with friends in Germany. We hiked up Kampenwand in Bavaria. While working my way through the snow and rocks, I realized mountain climbing safety tips were the same as electronic safety tips. Really! Here’s how.
Grabbing a soldering iron and throwing polarized components around a circuit board is something I often do. So often, I don’t even realize I’m using some of these electronic safety tips. However, a new activity gives you a chance to exercise the safety portion of your brain. Especially when there are no guard rails.
While constantly wondering “why am I doing this again?” I thought about these 6 electronic safety tips that I learned while climbing a mountain.
Current flow (direction) is the topic I’m planning for my next AddOhms tutorial. While preparing the script, I started to realize there are some myths or misunderstandings about electricity and current flow.
Everyone probably knows Ben Franklin. He discovered electricity, of course! Yet, he didn’t. Franklin was the first to prove that lightning was composed of electricity with his famous kite experiment. He was also the first to provide electricity’s well-known labels: positive and negative. And somewhere in there Franklin became famous for “inventing” conventional current flow.
This convention creates a lot of confusion around conventional and electron current flow. It’s a concept that has been covered by many others and may even be covered by an Electronics Tutorial Video Series in the future.
Instead, I want to explore some common current flow myths even I believed at some point. Continue Reading »
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A switching voltage regulator is one of my favorite circuits. In school, they were the first circuits I built where I understood how transistors worked. In fact, they were the first circuit I saw an inductor being useful! Switching regulators are incredibly efficient when designed properly. Of course, this detail about design is important. They are not as simple as a linear regulator, which is basically an IC and two caps.
To understand the basics of a switching regulator, I released AddOhms #18 this week. This is video tutorial dedicated the Switching Voltage Regulator. If video tutorials aren’t your thing, then keep reading for my written tutorial.
Dreaming of bringing a new hardware product to market? Perhaps you think your product will make the world a better place, or maybe you just dream of making millions of dollars.
Developing a prototype based on an Arduino (Genuino outside the USA), or other development kit, is a great first step. But there is still much work to do if you want to make your product into something that can be manufactured in volume and sold to the masses.
So I’m going to break down the process for you into a few manageable steps: Continue Reading »
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Previously I wrote up why the 9V battery sucks. As I thought more about that post, I realized, I never explained how much energy is in a 9 V battery versus say a couple of AA batteries.
For this post, I’m going to break down the energy stored in a 9 V battery, the small rectangular kind and compare it to what you get with 6 AA batteries. Yes, it takes up a little more space, but you might be surprised by the difference.
A DMM, or multimeter, is the go-to instrument for debugging most circuits. You probably already have at least one DMM on your bench for this reason. Me? I have three. But that’s a different story. Let’s talk about a Logic Analyzer.
Digital signals represent two states: on (usually “1”) and off (usually “0”). A multimeter (DMM) may be of limited value for these signals. When using the DC voltage measurement, you can see “something” is happening, but not exactly what that “something” is. For example on a PWM pin, you’ll see the RMS Voltage change as you modify the duty cycle. However, you can not see if the signal is “ringing” when turning on and off.
For debugging digital signals, a popular option is to use a Logic Analyzer. If you are not familiar with a logic analyzer, or you are not sure if you need one, this tutorial should help.
First I’ll give a simple overview of what a Logic Analyzer does, some considerations when to use one, and then give some terms to know when looking at them.