Category Archives: Curated

Creating A PCB In Everything: Upverter

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For the last five months, I’ve been writing a series of posts describing how to build a PCB in every piece of software out there. Every post in this series takes a reference schematic and board, and recreates all the elements in a completely new PCB tool.

There are three reasons why this sort of review is valuable. First, each post in this series is effectively a review of a particular tool. Already we’ve done Fritzing (thumbs down), KiCad (thumbs up), Eagle (thumbs up), and Protel Autotrax (interesting from a historical perspective). Secondly, each post in this series is a …read more

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Early Electromechanical Circuits

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In the days before semiconductor diodes, transistors, or even vacuum tubes, mechanical means were used for doing many of the same things. But there’s still plenty of fun to be had in using those mechanical means today, as [Manuel] did recently with his relay computer. This post is a walk through some circuits that used those mechanical solutions before the invention of the more electronic and less mechanical means came along.

Coherer Morse Code Receiver

The circuit shown below is a fun one, especially if you’ve played with crystal radios. It receives Morse code that’s transmitted as bursts of radio …read more

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Increase The Range Of An ESP8266 With Duct Tape

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For the longest time now, I’ve wanted to build a real, proper radio telescope. To me, this means a large parabolic reflector, a feed horn made of brass sheet, coat hanger wire, and at least for the initial experiments, an RTL-SDR dongle. I’ve done the calculations, looked at old C-band antennas on Craigslist, and even designed a mount or two that would make pointing the dish possible. I’ve done enough planning to know the results wouldn’t be great. After months of work, the best I could ever hope for is a very low-resolution image of the galactic plane. If I …read more

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Let’s Prototype! This Filament End Needs 80 Decibels

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Reaching the end of a spool of filament when 3D printing is inevitable. The result ranges from minor annoyance to ruined print. Recently, I needed to print a number of large jobs that used just over half a spool of plastic each. Unwilling to start every print with a fresh spool (and shelve a 60% used one afterward), I had a problem to solve. What my 3D printer needed was filament monitor, or at least that’s what I thought.

After reviewing some projects and aftermarket options, I ended up making my own. Like most prototypes, it wasn’t an instant success,

…read more

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PCB Design Guidelines to Minimize RF Transmissions

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There are certain design guidelines for PCBs that don’t make a lot of sense, and practices that seem excessive and unnecessary. Often these are motivated by the black magic that is RF transmission. This is either an unfortunate and unintended consequence of electronic circuits, or a magical and useful feature of them, and a lot of design time goes into reducing or removing these effects or tuning them.

You’re wondering how important this is for your projects and whether you should worry about unintentional radiated emissions. On the Baddeley scale of importance:

  • Pffffft – You’re building a one-off project that

…read more

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Tools of the Trade – Thermoforming

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Chances are good that you’ve already lost some blood to thermoforming, the plastics manufacturing process that turns a flat sheet of material into an unopenable clamshell package, tray inside a box, plastic cup, or leftover food container.  Besides being a source of unboxing danger, it’s actually a useful technique to have in your fabrication toolchest. In this issue of Tools of the Trade, we look at how thermoforming is used in products, and how you can hack it yourself.

The process is simple; take a sheet of plastic material, usually really thin stuff, but it can get as thick as …read more

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A How-To in Homebrew Design, Fab, and Assembly with Structural Framing Systems

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At this point, the internet is crawling with butt-kicking homebrew 3D printers made with extruded profiles, but it’s easy to underestimate the difficulty in getting there. Sure, most vendors sell a suite of interlocking connectors, but how well do these structural framing systems actually fare when put to the task of handling a build with sub-millimeter tolerances?

I’ve been playing around with these parts for about two years. What I’ve found is that, yes, precise and accurate results are possible. Nevertheless, those results came to me after I failed and–dry, rinse, repeat–failed again! Only after I understood the limits of …read more

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A Realistic Look At The Death of A Standard

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A bit ago I wrote an article called, “Death To The 3.5mm Audio Jack, Long Live Wireless.” A few readers were with me, a few were indifferent, many were vehemently against me, and there was a, not insubstantial, subset in a pure panic about the potential retirement of a beloved connector. Now I used a lot of opinionated language dispersed with subjectively evaluated facts to make a case that the connector is out. Not today maybe, but there is certainly a tomorrow not so far off where there are more wireless headsets at the electronics store than wired ones.

So …read more

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Tools of the Trade – Injection Molding

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Having finished the Tools of the Trade series on circuit board assembly, let’s look at some of the common methods for doing enclosures. First, and possibly the most common, is injection molding. This is the process of taking hot plastic, squirting it through a small hole and into a cavity, letting it cool, and then removing the hardened plastic formed in the shape of the cavity.

The machine itself has three major parts; the hopper, the screw, and the mold. The hopper is where the plastic pellets are dumped in. These pellets are tiny flecks of plastic, and if the …read more

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Hams in Space Part 2: The Manned Spaceflights

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Whether it’s trying to make contacts across the planet with a transmitter that would have a hard time lighting an LED, or blasting signals into space and bouncing them off the moon, amateur radio operators have always been on the forefront of communications technology. As mankind took to space in the 1950s and 1960s, hams went along for the ride with the first private satellites. But as successful as the OSCAR satellites were, they were still at best only beacons or repeaters in space. What was needed was the human touch – a real live operator making contacts with people …read more

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