Collaborate Disseminate
Yesterday we published a first look at the hardware found on the DEF CON 27 badge. Sporting a magnetically coupled wireless communications scheme rather than an RF-based one, and an interesting way to attach the lanyard both caught my attention right away. But the gemstone faceplate and LED diffuser has …read more
Continue reading DEF CON 27: The Badge Talk; or That One Time Joe Grand Sourced 30,000 Gemstones
Summer in the Northern hemisphere means outdoor cooking. Matches are old school, and you are more likely to use a piezoelectric lighter to start your grill. [Steve Mould] has one, but he didn’t understand the physics behind why it works, so he decided to do the research and share it …read more
We’ve read a lot about oscillators, but crystal oscillators seem to be a bit of a mystery. Hobby-level books tend to say, build a circuit like this and then mess with it until it oscillates. Engineering texts tend to go on about loop gains but aren’t very clear about practice. A [circuit digest] post that continues a series on oscillators has a good, practical treatment of the subject.
Crystals are made to have a natural resonant frequency and will oscillate at that frequency or a multiple thereof with the proper excitation. The trick, of course, is finding the proper excitation. …read more
There was a time when anyone involved with radio transmitting — ham operators, CB’ers, scanner enthusiasts, or remote control model fans — had a collection of crystals. Before frequency synthesis, because popular, this was the best way to set an accurate frequency. At one time, these were commonly available, and there were many places to order custom cut crystals.
One of the best-known US manufacturers of quartz crystals still around is International Crystal Manufacturing (ICM). Well, that is, until now. ICM recently announced they were ceasing operations after 66 years. They expect to completely shut down by May.
In a …read more
What’s the minimal BOM for a working amateur radio transmitter? Looks like you can get away with seven parts, or eight if you include the walnut. You’ve got to have a walnut.
Some hams really love the challenge of QRP, or the deliberate use of low-power transmitters to provide a challenge to making long-distance contacts. We’ve covered the world of QRP before and noted that while QRP rigs don’t throw a lot of power, it doesn’t mean that they need to be simple. Some get quite complex and support many different modulation schemes, even digital modes. With only a single …read more
Accurate timing is one of the most basic requirements for so much of the technology we take for granted, yet how many of us pause to consider the component that enables us to have it? The quartz crystal is our go-to standard when we need an affordable, known, and stable clock frequency for our microprocessors and other digital circuits. Perhaps it’s time we took a closer look at it.
The first electronic oscillators at radio frequencies relied on the electrical properties of tuned circuits featuring inductors and capacitors to keep them on-frequency. Tuned circuits are cheap and easy to produce, …read more
