Dave Richards (a.k.a. AA7EE) has a nice write-up about building another Si5351 VFO project:
To many, this will be just another Si5351 VFO project, with nothing to distinguish it from the others. In fact, that’s exactly what it is. The “how to” of connecting an Arduino board to an Si5351 board, wiring up a display, and loading the firmware, is straightforward, and well established. To me though, it was a complete mystery.
There are a lot of cheap electromagnetic radiation testers out there which boast some quite impressive claims. So I decided to pick up a popular one (GM3120) from eBay to see how well it works. And perhaps more importantly, I wanted to take a look inside to see how the E field and H field sensing is done.
Most professional field strength meters feature a dome-like sensor. Housed inside are three orthogonally arranged antennas used for picking up field component in that axis. A cheap tester like the GM3120 clearly doesn’t utilize this kind of sensor topology and presumably can only discern field strength along a single axis.
App note from CREE on driving LEDs over its specified current capability. Link here (PDF)
The Applications Engineering team at Cree is often asked whether it is safe to operate Cree XLamp® LEDs with pulsed currents above the maximum data-sheet rating. This question is usually asked in the context of legitimate product requirements such as those posed by emergency-vehicle applications, specialized stroboscopic illumination and even pulsed modulation for general-illumination dimming applications.
The short answer is “it depends.” Multiple variables affect both initial and long-term performance and reliability of an LED. These include thermal resistance, pulse duration, as well as current amplitude, frequency and duty cycle.
Application note from CREE on efficiently designing a conventional FR4 PCB to manage thermal heat and as a cheap alternative to metal core pcbs. Link here (PDF)
One of the most critical design parameters for an LED illumination system is the system’s ability to draw heat away from the LED junction. High operating temperatures at the LED junction adversely affect the performance of LEDs, resulting in decreased light output and lifetime. To properly manage this heat, specific practices should be followed in the design, assembly and operation of LEDs in lighting applications.
Matt Brailsford (aka Circuitbeard) has a nice write-up about building his mini pinball machine with a lattepanda core running dual monitors:
I generally start my projects by thinking about the hardware that I’m going to want to use as I’ll need to know sizes when it comes to the design phase. My first thought was to go with a Rasberry Pi as it’s what I’m familiar with and it’s what I’ve used for my other arcades, but after looking online, there really didn’t seem to be any good options for pinball emulation on Linux at all. It all seemed to be windows based. Thankfully I remembered reading about a single board Windows computer called a LattePanda so I thought why not give that a go and so this was the approach I ended up taking.
The NickelBot is complete and it works great. The goal of the project was to create an easily portable machine that creates low cost items that could be given away at events like Maker Faires. I think it has completely achieved that goal. The nickels are purchased from Amazon and cost about $0.08 each.
Makervilla is back! It will be held on August 13th, 14th, 15th and 16th at Batam, Indonesia.
MAKERVILLA 2.0 is a 4-day creative learning retreat designed for local and international maker educators to gather under one roof for a time of learning, dreaming, hacking and sharing of ideas.
MAKERVILLA 2.0 is specially organized to address the needs of educators who are involved with maker education. Whether it is the need for peer support or understanding how to develop curriculum ideas, MAKERVILLA 2.0 will be able to facilitate the formation of learning network, professional learning community and special interest groups.
MAKERVILLA 2.0 is organized by Onemaker Group Singapore in collaboration with Ruang Kreasi Indonesia.
Although I’ve been working with AVR MCUs for a number of years now, I had never made a high voltage programmer. I’ve seen some HVSP fuse resetter projects I liked, but I don’t have a tiny2313. I think I was also hesitant to hook up 12V to an AVR, since I had fried my first ATMega328 Pro Mini by accidentally connecting a 12V source to VCC. However, if you want to be an expert AVR hacker, you’ll have to tackle high-voltage programming. Harking back to my Piggy-Prog project, I realized I could do something similar for a fuse resetter, which would simplify the wiring and reduce the parts count.
One area of silicon reverse engineering which has interested me is the delayering of a chip to see each layer which allows superior visibility into the circuitry. I know of two ways: chemical etch and mechanical means.
In this video I try to make a mechanical grinder which can take micron levels of material away: a partial success. Parts are ground but I was not able to keep the silicon absolutely flat. More study of the commercial units is warranted!