When I read the article “Build a Pocket-Sized Altair Computer” by David Hunter on building an Altair clone, I was reminded that I too had designed an Altair clone, but I built mine in 1977. Mine required seven boards in a 19” rack. This article details the resources I had then in a comparison of what resources are available today. I’ll also describe how I designed and built my clone.
A few months ago, I accepted a challenge: Design a way for people who can’t easily use a keyboard to create text for applications such as Word, OpenOffice, eBay, or Google via Morse code. It takes only two fingers to create them, and learning to send Morse code proves easier than learning to receive it, which requires much practice. See how I used a $10 Cypress Semiconductor CY8CKIT-059 MCU board to mimic a USB keyboard but without software drivers, code libraries, or special USB-interface ICs.
Nixies were introduced when vacuum tube hardware automatically provided the high voltage they require. These days, circuitry typically runs on five volts or less, so finding the +170V or so for Nixie anodes can be a bit of a challenge. Here are three transformer based ways to obtain that high voltage in line-powered semiconductor-based devices.
A few years ago, we brought you a story about a guy building ham radio antennas from aluminum crutches. Now, he's using cable TV coax for his dipoles.
After trying different things to troubleshoot an intermittent problem with my MicroBITX kit (multi-band, software-defined ham radio transceiver), it turned out static discharge was the answer to my problems
Keeping your batteries ready for action in your ham radio hobby is something we all have to deal with. How much does “memory effect” come into play with recharging? Does it really exist? Let’s look at some different failure modes and what might really be behind them.
Are you bored with conventional two-dimensional circuit layouts, or looking for a way to add an artistic flair to your next project? I’ve taken point-to-point construction style a step further by making it self-supporting, which opens up a wide range of physical circuit topologies. (Point-to-point construction usually uses supporting structures like terminal strips that are functional but not pleasing to the eye.) I call this construction style the copper cobweb. Here’s how to do it.
Even when a circuit functions as it’s supposed to, it’s not always easy to tell what it’s doing. Plus, waiting for an output (especially if there’s a long delay involved) is not always practical. Conversely, if a circuit does not function, the only means to find out what’s wrong is to troubleshoot it with either a multimeter or oscilloscope. Wouldn’t it be great if the circuit itself could tell us more directly what’s wrong?
Short of living underground in the wilderness without electricity, battery power, or Internet, exposure to electromagnetic radiation can’t be avoided. The best thing you can do is look at the guidelines provided by organizations like the FCC and ARRL, and use a little common sense.
It took me eight months of part-time work to restore all 168 pounds of a Heathkit “H-1.” I would like to share a few of the trials and tribulations I went through to resurrect this beast.
