SI5351 VFO project

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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.

See the full post on his blog here.

#FreePCB via Twitter to 2 random RTs

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Every Tuesday we give away two coupons for the free PCB drawer via Twitter. This post was announced on Twitter, and in 24 hours we’ll send coupon codes to two random retweeters. Don’t forget there’s free PCBs three times a every week:

  • Hate Twitter and Facebook? Free PCB Sunday is the classic PCB giveaway. Catch it every Sunday, right here on the blog
  • Tweet-a-PCB Tuesday. Follow us and get boards in 144 characters or less
  • Facebook PCB Friday. Free PCBs will be your friend for the weekend

Some stuff:

  • Yes, we’ll mail it anywhere in the world!
  • Check out how we mail PCBs worldwide video.
  • We’ll contact you via Twitter with a coupon code for the PCB drawer.
  • Limit one PCB per address per month please.
  • Like everything else on this site, PCBs are offered without warranty.

We try to stagger free PCB posts so every time zone has a chance to participate, but the best way to see it first is to subscribe to the RSS feed, follow us on Twitter, or like us on Facebook.

Teardown of a GM3120 electromagnetic radiation tester

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Kerry Wong did a teardown of a cheap GM3120 field strength meter:

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.

See the full post on his blog here.

Check out the video after the break.

ESP32, PlatformIO

PlatformIO is an opensource ecosystem (as it’s defined in the homepage of the project) to develop IoT projects.

The heart of the platform is a software component named PlatformIO Core. This component includes:

  • a cross-platform compiler
  • a libraries and dependences manager
  • a serial monitor

PlatformIO Core is developed in Python and therefore it can run on different operating systems (Windows, Linux, MacOS).

Although you can use the Core component directly, PlatformIO’s strength lies in its IDE, which allows the development of multi-platform projects and integrates with the Core itself.

In this article I’m going to show you how to use PlatformIO to develop projects running on the esp32 chip.

Installation

PlatformIO IDE is provided as a plugin for two different development tools: Atom and VisualStudio Code. I tried both solutions and I preferred VSCode: both the installation and the use are simpler and more immediate.

Install VSCode after having downloaded the package from Microsoft’s website (the installer is available for Windows, Linux and MacOS).

Open the Package Manager:

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search the PlatformIO IDE package, then click on Install:

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wait until the installation is complete:

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Hello world

Now it’s time to develop your first program, which traditionally will display the sentence Hello world! on the terminal.

If it doesn’t show up automatically, open the PlatformIO’s homepage:

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then click on New Project:

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give a name to the project and choose a devboard based on the esp32 chip (in this example I’ll use a Lolin32 board by Wemos). PlatformIO supports both the esp-idf framework and the arduino-esp32 one. All my tutorials are based on the first one:

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PlatformIO automatically creates some folders for your project. Choose the src folder (it stands for source, that is the folder which will contain the source code) and create a new file:

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name the file main.c and type the simple program as it follows:

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run the compiler by clicking on the corresponding button in the bottom bar:

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the editor displays an error… indeed your code is using the printf() function without having included the library:

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add the missing line, now you should be able to complile the code without errors:

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PlatformIO can also upload the compiled program to your board. Thanks to its auto-detect feature, you usually don’t need to specify the serial port the board is connected to:

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Serial monitor

PlatformIO also includes a serial monitor you can use to test your program. By default, this monitor connects to the serial port with a speed of 9600 baud. The esp32 chip instead has a default speed of 115200 baud; you have therefore to change the platformio.ini file included in your folder as it follows:

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Now open the serial monitor; you should see the correct output of your program:

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Conclusions

I found the use of PlatformIO really immediate: after a few minutes I was able to develop, compile, load and test a program. Try it and leave a comment with your impressions!

 

App note: Pulsed Over-Current Driving of LEDs

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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.

App note: Optimizing PCB Thermal Performance for LEDs

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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.

Rombus pinball – a LattePanda mini pinball machine

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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.

Build log at Circuitbeard blog and the GitHub repository here.

Check out the video after the break.

Mostly PIC16C57

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CAPS0ff team posted an article taking a closer look at 8 “PIC16C57s”:

We were recently sent 8 “PIC16C57s” from:

*High Seas Havoc (403/C013)
*Wargods (U69, C020)
*MACE (U96, C021)
*Carnevil (U96, C022)
*BioFreaks (C023)
*Gauntlet Dark Legacy (C024)
*Gauntlet (U37, C025)
*Blitz 99 (U96, C026)

More details at CAPS0ff blog.

Nickelbot – wooden nickel laser engraver

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bdring posted an update on NickelBot project we covered previously:

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.

Project info at Buildlog.Net blog.

Check out the video after the break.