Electronics Projects Index

After transitioning to WordPress, I started writing up my newer projects as ‘blog posts’ rather than ‘pages’. Please find below a list of links to every electronics project related blog post:

• Battery operated ESP8266 Wifi Button to trigger my sprinkler system

Use a battery-operated ESP8266 ESP-01 module as a wifi trigger for home automation.



• A basic and RAM board for HP-9000 series computers


• Assembling a thin client to serve as an HPDrive


• Raspberry Pi Floppy Controller Board

This floppy controller hat for the raspberry pi allows you to connect vintage floppy drives (360K, 720K, 1.2MB, 1.44MB, etc) to your raspberry pi model 4B.



• HP 27201A Speech Output Module, first speech synthesizer designed by a major computer manufacturer!

Teardown and reverse engineering of the HP 27201A speech output module, which uses the TMS5220 speech processor IC and was designed to be used with the HP 1000 and HP 3000 series minicomputers.



• The VTEK Small Talk Plus Epson HX-20, World First Laptop — Talking!


• This is Digitalker! … and Jameco JE520 too. Vintage Speech Synthesis.


• Cloning the ET-3404 6809 adapter for the Heathkit ET-3400


• Designing a Memory/IO (ETA-3400) addon for the ET-3400 Trainer


• Overclocking the pi4 with the Blink Blink ICE Tower CPU Cooling Fan


• Supercapacitor Uninterruptable Power Supply (UPS) for Raspberry Pi


• The Hayes Chronograph, a Remake for 2020


• Tandy 1000 Upgrades / PS2-Tandy Keyboard Adapter


• Restoring a Convergent Technologies NGEN PC/Workstation (Burroughs B25 / Unisys)


• Raspberry Pi Controlled DC Load


• Hot Shoe to 1/4-20 Quick Release Magnetic Mount for LumeCube


• Building a Power-over-Ethernet (PoE) Power supply using a DPS5005 module


• Scott’s FrankenNUC: 10Gbe Fiber Network on a 5th Generation Intel NUC 5i7RYH


• RAIN: Redundant Arrays of (In)expensive NUCs


• DIY Wireless Temp/Humid/Pressure sensors with Raspberry Pi Receiver, for monitoring stored 3D printer Filament


• Raspberry Pi 4: Do you need a fan? What’s the best fan for a raspberry pi 4?


• Vacuum Fluorescent Display (VFD) on a Prusa I3 Mk3 Printer


• The Nixie Tube Filadometer – A Nixie Tube Filament Meter for your 3D Printer


• COB LED Panels: 10 watt, 70 watt, and 200 watt.


• Resistive Load, Constant-Current Power Supplies, and a 3D Printed Desk Lamp


• 3D Printer OctoPrint Monitoring with Prometheus and Grafana


• Raspberry pi based indoor air quality monitor


• Building the ultimate USB power distribution system


• Making the e-paper equivalent of an Etch-a-Sketch


• Yet Another Masterplay Clone


• Atari 5200 Playstation 2 Dual-shock controller adapter


• Homemade Atari 5200 Analog Controller


• Scott’s Z80SBC: Z80 Single Board Computer


• Pi-Powered Atari 5200 Multi-ROM Cartridge (MultiCart)


• Raspberry Pi Virtual Floppy for ISA (PC XT/AT) Computers


• Converting a Seeburg 3WA Wallbox into a Remote for a Modern Music Player


• 8-bit ISA DiskOnChip / RTC board


• Measuring USB Power Cable Voltage Drop with my DC Load


• Leia’s LED Clock


• Building a Micro 8088 Single Board Computer


• 8-Bit ISA EMS Board / Flash Disk Board


• PS2-TTLSerial Adapter for RC2014 and MIDI


• Raspberry Pi Midi Hat / Building a Raspberry Pi Midi Jukebox


• Vintage MIDI: Roland MT-32, Roland SC-55, HardMPU, and an Xi 8088


• CTS256A-AL2 Text-To-Speech Board


• ISA Speech Synthesizer board using SP0256A-AL2


• Z80 Retrocomputing 18 – Z180 CPU Board for RC2014


• Z80 Retrocomputing 17: Enhanced Z80 CPU Board for RC2014


• Building an Xi 8088 PC


• Z80 Retrocomputing 16 – Unix on RC2014


• Z80 Retrocomputing 15 – CP/M on RC2014 Revisted, Using RomWBW


• Qume 842 8″ floppy drive with a RC2014 Z80 retrocomputer


• Building a Zeta V2 Single Board Computer


• Z80 Retrocomputing Part 14 – RC2014 Floppy Controller Boards


• Z80 Retrocomputing 13 – RC2014 VFD Display Board


• Z80 Retrocomputing 12 – Talking Nixie Tube Clock


• Z80 Power-on reset circuits


• Z80 retrocomputing 11 – CP/M on the RC2014


• Z80 Retrocomputing 10 – RC2014 CompactFlash board


• Nixie Calculator Update – PCB availability, source code, design notes


• Z80 Retrocomputing 9 – CTC and dual serial ports for RC2014


• Z80 Retrocomputing 8 – Speech Synthesizer for RC2014


• SP0256A-AL2 speech synthesizer chips: Genuine vs Counterfeit.


• Z80 Retrocomputing 7 – RC2014 DAC (Digital To Analog Converter)


• Z80 Retrocomputing 6 – RC2014 TIL311 Front Panel Board


• Z80 Retrocomputing 5 – Single Stepper for RC2014


• Z80 Retrocomputing 4 – Bus Supervisor


• Z80 Retrocomputing 3 – Bus Monitor Board


• Z80 Retrocomputing 2 – Real Time Clock for the RC2014

I developed my first add-on board for the RC2014. This board is a real-time clock and an 8-bit output port. I'll use it to build a Nixie Tube Clock.



• Intro to Z80 Retrocomputing

This is the first in my series of Z80 retrocomputing blog posts. It serves as an introduction. I started by building the RC2014, a popular retrocomputer platform that I found on Tindie.



• Building the Dutchtronix Scope Clock


• Product Reviews: Mooshimeter, Raspberry Pi Black Slices Case, Powerhorse Surface Cleaner


• Magic Eye Tube Audio Spectrum Analyzer

In this post, I put together a magic eye tube spectrum analyzer using my two-tube boards, op-amp boards, and a spectrum analyzer board that uses the BA3830S chip.



• Magic Eye Tube PC Monitor

I thought it would be cool to use magic eye tubes to visualize the activity on my PC, so I threw together a two-tube project that shows CPU utilization and network utilization.



• Magic Eye Tube interfacing with a Raspberry Pi

I discovered magic eye tubes on eBay. I bought a couple of cheap and simple boards and assembled them. Then I tried to see what it would take to control the tubes from a Raspberry Pi.



• DIY Nixie Tube Frequency Counter

I've always wanted a Nixie Tube Frequency Counter, but one has never come up on eBay for a price that I was willing to pay. So I just made my own using the same Nixie Tube boards as the calculator project. I learned a bit about frequency counter front-ends in the process.



• Raspberry Pi Switching Power Supply Shield

There are many times when I want to power one of my Raspberry Pi projects from 12V instead of 5V. I built this switching power supply shield to make it easy to do so.



• Eico 430 Oscilloscope

I bought an Eico 430 Oscilloscope, an old analog scope from the late 50s / early 60s. It's a cathode ray tube scope, with vacuum tubes used throughout. It works amazingly well given its age, and will actually be a useful addition to the bench.



• Sparkfun third hand kit – review and modifications

I've always wanted the Sparkfun third hand kit, ever since I saw it in their new products page. I finally bought one, and this post contains my review, as well as some modifications.



• Aoyue 128 Soldering Tip Polisher Review

The Aoyue 128 is a soldering tip cleaner. It has two rotating brass brushes that clean and polish your soldering iron type. I bought it on a whim, and review it in this post.



• Eico 369 RF Sweep Generator

I bought an Eico 369 RF Sweep Generator. The video covers my experiences with it, from the moment I unboxed it to when I made the first sweep.



• DIY Digital RF Attenuator

I build a digital RF stepped attenuator. It uses a PE4302 chip, along with an RGB encoder and a VFD display. It attenuates from 0 to 31.5dB in 0.5dB steps.



• Sinometer VC2000 Frequency Counter Review

I review the Sinometer VC2000 Frequency Counter. You can buy one on Amazon for less than a hundred bucks.



• RGB Rotary Encoder on a Raspberry Pi

The video in this blog entry shows how to connect a rotary encoder to the Raspberry Pi. The particular encoder is from SparkFun and contains a pushbutton switch as well as a tri-color LED.



• Polaroid 312 LED Camera Light – Teardown and Repair

People may have noticed my Camera Light shut down unexpectedly during the Pilotuner video. I finally got around to tearing the camera light apart and fixing it.



• DIY Variable AC Power Supply

I build a 0-30V adjustable AC power supply for the bench using a Variac, 28 VAC transformer, a digital panel meter, and a handful of other support components.



• Pilotuner T601 FM Tube Tuner Restoration

I restore a Pilotuner T601 FM tuner. This is an interesting piece of history, as it's one of the earliest FM tuners. It doesn't even have an amplifier and is designed to be attached to an existing radio or receiver.



• Hantek T3100 scope probes unboxing and review

I evaluate some Hantek T3100 oscilloscope probes. These are x100 probes, that I bought for using on high-voltage projects, such as tube radios.



• Ebay VCO module evaluation

I ordered some cheap VCO modules from eBay. Only $20, using an MC1648 VCO oscillator chip, and they work from 70Mhz to 200Mhz.



• LM2576 constant voltage / constant current switching power supply

I design an adjustable voltage / adjustable current limit power supply using an LM2576 buck converter. For the current limit function, I use an op-amp to measure the current from a sense resistor, a second op-amp to compare that to a pot, and then feed that signal back into the feedback pin.



• DIY RF Signal Generator

I build an RF signal generator from an article in Nuts and Volts. I learned many things about RF circuits during this project, and the blog post details some of the lessons.



• Learning to use the GALI-55 MMIC

I didn't know what the heck I was doing when I tried to use a GALI-55 MMIC in my RF signal generator. A few basic mistakes led to hours of diagnosing the problem.



• My new KG-650 RF Signal Generator

I bought an old tube RF generator on eBay. It works surprising well considering the age of the technology. I use my Rigol scope to view some of the waveforms and play with the RF generator a bit.



• Creating the ultimate home automation keypad

I wanted a control center mounted to my monitor that I could use for important home automation functions. I build some custom keypads using Cherry MX blue keyswitches and interface them to a Raspberry Pi. I add a VFD display for status info.



• Interfacing a VFD display to the raspberry pi

I interface a vacuum fluorescent display to a Raspberry Pi.



• GE iTwinkle 36 LED Christmas light teardown and hacking

The availability of GE35 color effects sets, the ones that have been hacked since 2010, is poor. In this article I tear apart one of the new iTwinkle sets to see if they are compatible with the same hack.



• Raspberry Pi Powered Individually Addressable Christmas Lights

GE G35 Christmas bulbs are easily hackable. I wanted to control them with my Raspberry Pi, and this describes how I used a Parallax Propeller to do the intermediate protocol handling.



• Nixie Tube Calculator, Powered by a Raspberry Pi

My latest Nixie Tube Project, a desktop calculator controlled by the Raspberry Pi. It's currently on Kickstarter!



• Raspberry Pi Nixie Tube Clock Prototype

Nixie tube clock prototype using IN-12 Nixie tubes with a Raspberry PI. 74141 / K155D drivers are used with 74HCT595 shift registers.



• A temperature and humidity probe for the Elk M1 Gold

I design and build a temperature and humidity probe for the Elk M1 Gold Alarm / Home automation panel. A parallax propeller microcontroller and an SHT11 sensor is used.