AddOhms on Bald Engineer

Measuring Apple II CPU's Glitchy Clock

Wed, 20 Mar 2024 17:58:51 +0000

The Apple II’s CPU clock has jitter or a glitch. This issue is not new—it has been present since its original design in 1977! Bald Engineer uses an oscilloscope to show how often the glitch occurs and how to correlate that jitter to its source—which is useful when you are not testing 40-year-old devices. The device under test (DUT) in this video is the Mega IIe project. It’s a fully compatible Apple IIe built around the Mega II chip.

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Eight KiCad 8 features I like

Mon, 26 Feb 2024 16:23:38 +0000

KiCad 8 just dropped. Here’s an AddOhms video covering eight must-try features! The February 2024 release brings a whole host of new stuff to the Schematic editor. However, the PCB editor, CLI, and Simulation tools also received attention. (There are something like 900 closed issues for the 8.0.0 Milestone!) Which of these is your favorite? In the video, I cover: Property Manager Panel (is now everywhere) A fix for Symbol pin or wire end off connection grid! Easily access alternate pin functions (on symbols with them) Pin Helpers save time Edit Power Symbols (instead of creating new library parts) Net Navigator and Search panels help with large schematics Improved custom polygon tools in PCB (Combined) Teardrop support and Length-Tuning improvements This AddOhms post covers my top 8 in more detail. Or, you could just watch the video!

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5 LDO Regulator Considerations other than voltage and current

Wed, 30 May 2018 13:03:28 +0000

For an AddOhms series, I created a DIY Arduino I am calling the “Pyramiduino.” It is an ATmega328p based board in the shape of a triangle. Other than being cute, the shape does not offer any other benefit. The design features a 3.3 volt LDO Regulator, which is also the subject of this post. I forgot a fundamental aspect of design: read the freaking datasheet. The board’s LDO regulator was not turning on. Adding a passive scope probe to the circuit suddenly fixed the problem. The regulator turned on. When touching the enable pin, it measured about 1.25 volts. While I am sure Rohde & Schwarz would like me to ship scope probe with each board, that was not an option. With the impractical fix in place, I got to thinking about that voltage level. I remembered that the datasheet mentioned about 1.2 volts was needed for the “HIGH” threshold. Which meant, 1.25 volts applied to the pin enabled an active low input. Not only that, I remember the datasheet clearly said it had a pull-down resistor built-in. What was going on?

DIY Arduino Schematic board and Checklist

Wed, 17 Jan 2018 14:00:18 +0000

One of the last significant steps in a project is designing the custom PCB. This stage means creating a DIY Arduino board that is custom to the application. Two examples of my past projects are BinBoo, a Binary Clock, and Open Vapors, my reflow oven controller. While working on a project for a friend, I got to thinking; it would be nice to have a checklist for circuit elements to include on a DIY Arduino board. In the early days, I forgot to add a filter cap to AREF, for example.

Switching Voltage Regulator Tutorial

Wed, 13 Apr 2016 13:00:04 +0000

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.

2015 Holiday Gift Guide

Wed, 25 Nov 2015 16:00:49 +0000

This week marks the start of the 2015 Holiday Shopping Season. Being a short week for me, I thought I’d offer up some gift suggestions for engineers. Being the only engineer in my immediate family, gift giving time is always interesting. Many times I wished I could give them a list of unusual items, without saying “here buy these.” Whether you want to gift something to a fellow electronics enginerd or you to offer your family some suggestions, there is something on this list.

Don't be afraid of learning a new tool

Wed, 08 Apr 2015 14:07:13 +0000

Behind-The-Scenes of AddOhms #14 After moving from learning a new tool to mastery, the resistance for me to switch becomes very high. This can apply to hardware tools like a drill, saw or CNC milling machine. It can also apply to software tools like EAGLE, Programming Languages or video editing software. In AddOhms #14, I gave an overview of the VirtualBench from National Instruments which I’ve covered on this blog as a hands-on, written review and video review.

AddOhms Electronics Tutorials DVD Now Available

Wed, 25 Feb 2015 15:12:56 +0000

When I was in elementary school, I remember Ms. Coker telling us we needed to memorize our multiplication tables because we wouldn’t always have a calculator. Years later in college I was told, “learn to use the library, it’s not like you can carry the internet in your pocket.” Buy On Tindie Seems strange that I always carry 3 devices on me that do both. Today a generation of people are growing up with the mass of all human knowledge available to them from birth. No formal education is necessary. And the only need is a modern device with WiFi.

5 (Electrical) Engineering Podcasts You Should Subscribe

Wed, 18 Feb 2015 15:25:12 +0000

Podcasts are an amazing way to extend your knowledge in any subject. This (generally) free content is updated often, comes in a variety of formats, and covers nearly every subject. Your definition of Podcast might vary from mine. So for this list it means: content regularly produced with the intention of informing on a particular subject which is available either as audio, video, and ideally a RSS feed. Keep reading to see the different electrical engineering podcasts I listen to.

AddOhms #8: LEDs and Current Limiting Resistors

Mon, 10 Feb 2014 12:00:49 +0000

The idea for AddOhms #8 has been around for quite some time. I’m always trying to find ways to explain why current limiting resistors are necessary. So while working in the shop one day, I decided to play with some LEDs and a bench-power supply. Then I decided to record what happens.

AddOhms #7 - Comparing Arduino and Raspberry Pi

Mon, 16 Dec 2013 12:00:59 +0000

The seventh AddOhms TutorialCast has gone “live”. (Gone “uploaded” sounds wrong.) Being able to understand difference between an Arduino and a Pi is a critical point for many new electronics hobbyist. The boards seem so similar, but they are so different. AddOhms #7: Comparing the Arduino and Raspberry Pi Full Episode Notes are available on the Episode’s homepage.

AddOhms #6: Analog and Digital

Wed, 13 Nov 2013 12:52:09 +0000

It isn’t always clear what is meant by calling a device or a signal “analog” and “digital”. This AddOhms tutorial explains the difference between analog and digital by using an analogy to clocks. Old-school clocks with hands are a great example of “analog” while alarm clocks with digits as their display are an excellent example of “digital”.

Understand the difference between DC and AC

Wed, 25 Sep 2013 14:10:17 +0000

The fifth episode of AddOhms tackled the difference between AC and DC. One of the things I wanted to stress in this tutorial is that even though the acronyms stand for “current”, they get used to describe voltages as well. Which, after a video on the difference between voltage and current, seemed like something that needed to be stated.

A new series on AddOhms, Electronics basics, starting with: Voltage, Current, and Power Explained.

Sat, 13 Jul 2013 00:53:31 +0000

Starting with this new AddOhms TutorialCast series, we are taking a look at Electronics Basics. The first topic is on the differences between Voltage, Current, and Power. The twist on this explanation is that we are not using the usual “electricity is like water” analogy engineers seem to love. Instead, we just use plain language to explain the difference between these concepts. From a production point of view, I am really having fun with these videos. Using some green card stock, imagination, and easy to use tools, I am able to achieve some pretty cool effects. Well, I think they are pretty cool. Check out this screen shot from Final Cut Pro X.

Introducing the AddOhms TutorialCast

Sun, 05 May 2013 20:53:51 +0000

Over the past several months I have been kicking around a new way to teach non-engineers about electronics. My idea is to use simple language to explain complex engineering subjects. Each video will be in the range of 3-5 minutes. While putting together the first couple of topics I started to realize I wanted this to be something to stand on its own. So I have created a separate webpage, twitter account, and YouTube Channel for this TutorialCast called “AddOhms.”

Added a G-Docs comparison chart to help pick an Arduino

Sat, 07 Jan 2012 04:37:44 +0000

Can’t decide which Arduino Board is for you? Have a board you want others to know about? This Google Docs Spreadsheet compares some of the key attributes of various Arduino boards. Whether you are trying to decide which one to buy or just want to know the differences, this chart can help.