I find medical instruments like an ECG-EKG unit really fascinating. To be able to watch the electronic firing signals of a heart is mesmerizing and informative. For parts costing less than $50, I built a unit that plugs into my laptop computer’s microphone input jack and displays stunningly clear ECG waveforms. The unit worked beautifully when I tested it on myself, my wife, and friends.
Over the years, I have accumulated a bunch of chips from before the era of true PCs when computers with names like Altair, KIM-1, and Cosmac ELF were popular. I’ve been looking for a way to use them in new projects, so I designed a system around a 40-pin PIC16F887. I figured this would put some of my historic chips to work and be a great learning tool for understanding how a microcomputer works.
You should hear what you’ve been missing!! The most unbiased source of international news today is shortwave radio. The propaganda style of the cold war is mostly gone and countries are often surprisingly honest about themselves and about the state of the world.
This DIY piece of test equipment combines a variable DC voltage reference, a programmable function wave generator, and a fully functional frequency counter. Plus, it costs under $200. It started out as a microcontroller controlled variable voltage reference using just a PIC, a fixed voltage reference, and a digital-to-analog converter. However, it expanded to include a programmable function generator that can produce a sine wave, triangle wave, square wave, etc. I then went further to include a frequency counter to measure the frequency of the function generator output.
In decades past, capacitor and resistor substitution boxes were very popular pieces of test equipment. These days, it seems folks have forgotten their value and ease of use. Here’s a discussion on how they work and the different options and styles available, so you can start using them for yourself.
This six-digit, beautifully designed timepiece showcases cold war era components — Numitrons instead of Nixie tubes — along with modern LEDs and a Microchip PIC to create not only a useful clock but a great conversation piece as well.
Building digital clocks may not be the sexiest of DIY projects, but it’s still pretty fun. Try this version that utilizes the ESP8266 family of devices which makes incorporating the Network Time Protocol simple.
I love restoring old electronic equipment. A while ago, I was excited to find a vintage Heathkit EC-1 analog computer for a reasonable price on eBay. It definitely needed a little TLC. Here’s how I brought it back to life.
I’ve enjoyed tracking wind speed for years with my Davis weather station. However, the tiny plot on the station’s LCD screen is not very resolved and I wanted it to be better ... a whole lot better. The solution: a Raspberry Pi!
Internal resistance within capacitors — known as Equivalent Series Resistance — can increase over time, causing power loss and/or heating. With this device, you can test your stash of capacitors so you can weed out any bad ones before you install them in your projects.
