Projects on Bald Engineer

Make Waveforms Misbehave on Purpose with ArbDraw

Sun, 13 Sep 2026 00:00:00 +0000

Sometimes the test signal needs a flaw. A clean waveform is easy to generate, but a narrow glitch in the middle of it can replicate a behavior or gives an oscilloscope something (in-band) specific to trigger on.

Mega IIe Supercon 2023 Talk is now Live!

Wed, 15 May 2024 13:06:13 +0000

I must extend a big “Thank You!” to Lewin Day at Hackaday for this excellent Mega IIe write-up. Accompanying the post is an archived recording of my Supercon 2023 talk. That talk is where I gave a complete overview of the Mega IIe project and showed off the final case design for the first time! This project is where I took the Mega-II chip out of an Apple IIGS and built a fully compatible Apple IIe around it—something that not even Apple ever did!

Watch this video on YouTube

WiFi-Enabled LED detector tells me when my Dehumidifier is Full!

Fri, 12 Apr 2024 23:40:13 +0000

I created a Wi-Fi-enabled LED Detector using Nordic’s nRF7002 Design Kit (DK). Using this box, I can detect when LEDs on appliances, like my lab’s dehumidifier, are on. In other words, my non-IoT tool can send me messages over the Internet now! And, because the nRF7002 has a dual-band Wi-Fi antenna, it does so on my 5 GHz network. I ran into a number of issues with this project, and I expected that. Except for the RF part of the design, which works fine! Links to the design files are available on the post on the element14 Community.

Watch this video on YouTube

Introducing Bit Preserve

Wed, 12 Jun 2019 18:13:01 +0000

A project I work on in my spare time is creating a portable Apple II. Like many of my projects, one leads into another. I started out wanting to make a mobile Apple II, and now I’m working on a project called Bit Preserve. How did I get from one project to the next? Well, as I looked into how to make a portable Apple II, I realized a significant issue. The original Apple II logic board has almost 80 ICs. Being a design from 1975, they are all through-hole packages. The good news is that except for the ROM chips, they are all off-the-shelf components. But such a size means it might be impossible to turn it into something handheld. I almost abandoned the project. Then, I learned about a chip included in the Apple IIgs. The name of the ASIC is “MEGA II.” (Nothing to do with Arduino.) It is a chip that integrates all of those off-the-shelf chips into an 84 pin package.

Drawing Apple MEGA-II Breakout in KiCad

Thu, 01 Nov 2018 13:00:30 +0000

There is a project that has been sitting on my “to do” list for too long. My lab notebook has several dedicated pages for it. But I have not made progress. I decided to take some advice I have given to other people. When you’re stuck on starting a task, break down the project until you find a piece small enough you can get it done with no problem. The project involves the Apple IIgs. It was Apple’s last 16-bit (and 8-bit) computer. Inside are some application specific integrated circuits or ASICs that make the IIgs. The name with my attention is named “MEGA-II.” It takes all of the individual logic chips from the original Apple II design and incorporates them into a single 84-pin PLCC.

Raspberry Pi Startup Script Tutorial

Wed, 28 Jun 2017 13:03:46 +0000

The last couple of weeks I have been making progress and posts on my RetroPie build. I’m putting a Raspberry Pi inside of an actual SNES (well Super Famicom). Part 1 covered the schematic for a Soft Power Controller. In Part 2 I broke down the RPSPC state machine. This 3rd and final post of the series is a Raspberry Pi startup script tutorial. It covers how to make scripts run at startup and shutdown.

Soft Power Controller State Machine

Wed, 21 Jun 2017 13:00:43 +0000

Previously I looked at the hardware needed to build a Raspberry Pi soft power supply. This week I’m looking the state machine for the microcontroller. Why is such a complicated circuit necessary? I am replacing a Super Famicom (SNES) motherboard with the Pi. The trick is, I want to use the original power switch to turn the Pi on and off. This requirement presents a problem. When the switch goes into the “OFF” position, power needs to stay on long enough for the Pi to properly shutdown. So the switch itself can’t provide power to the Pi directly. With minor changes, the code in this state machine could be made to work with push buttons as well. If I add that feature in the future, I’ll update the code on the RPSPC GitHub project.

Raspberry Pi Soft Power Controller - The Circuit

Wed, 03 May 2017 23:18:56 +0000

The RetroPie project enables retro-gaming with a Raspberry Pi. All of the Pi models have enough computing power to emulate the major 8-bit and 16-bit computers of the 80s and 90s. With the Pi 3 I have even been able to play PS1 games with no problem. My current project is to put my Raspberry Pi running RetroPie into an old Super Famicom (SFC), or SNES, case. The catch? I want the original SPST power switch to work. And by work, I mean allow the Raspberry Pi to shutdown properly when the switch goes into the off position. To accomplish this task, I am building a Raspberry Pi soft power controller.

3 Way Camera Shoe

Thu, 04 Aug 2016 13:29:19 +0000

When recording videos for either baldengineer.com or, more often, AddOhms, I need at least two things attached to my camera. I used a Canon T5i. The two devices I need to have connected are a shotgun microphone and a wireless receiver. In the past, I just let the remote’s wireless receiver dangle. That really bothered me. I’m still surprised this DSLR shoe adapter didn’t already exist on Thingiverse. Anyway, I created one. Head over to Thingiverse to download it.

Baldengineer's Projects Overview

Thu, 20 Dec 2012 22:33:15 +0000

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Row Your Boat, Part 1

Thu, 26 Mar 2009 02:28:39 +0000

This pattern is called Row Your Boat. As one of the strips starts to get brighter, a nearby strip will join in the fading. After completing a fade cycle, they start switching colors. There is a random strobe thrown in there as well. The first 10 seconds are with a diffuser (piece of paper), the last 10 seconds are without. The final panel will use a diffuser. The colors have no correction yet, so red is really dim and green is really bright. It looks like one of the channels of my TLC5940 is going bad. The center LED strip’s blue is very dim. I’m not going to look much into it right now though. Instead, I will wait until I fab a PCB for the 5940 (this weekend?)

Getting gEDA running on OS X

Mon, 23 Mar 2009 22:38:43 +0000

Quick schematic in gschem running on OS X. In an attempt to find a free set of schematic and PCB tools for hobby work, I looked back at gEDA. The last time I used it was when the project first started, years and years ago. I was happy to see that OS X had a set of fink packages for the gEDA suite. After figuring out how to get X11 in Leopard (since I didn’t include it when I installed 10.5) and install fink, getting gEDA going was a snap. The user jluciani in the Arduino forums has provided some free pcb footprints he has used from previous projects.

LED Strip Fun, First Try

Sun, 01 Mar 2009 15:28:33 +0000

Initially I tried to get a LCD screen working with my Illuminato based Arduino. After a couple of attempts I realized two things: 1. The Iluminato is not ready for prime time. and 2. I burned out the LCD. So I decided to move on to the LCD strips I have from Sparkfun. The program is pretty simple since I am using the PWM outputs. The first video is with the lights off and the second is with the lights on. I need work out the min / avg / max for the different colors. The next step is to create two columns (or rows) of LED strips, using a buffer chip.