App note: How to avoid chipLEDs sticking to cover tape during automated tape-and-reel assembly

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Investigative app note from Vishay on preventing too light components from sticking on the cover tape of their reel. Link here (PDF)

Customers have informed Vishay that 0603 LEDs (ChipLEDs) supplied in tape and reel format sometimes stick to the PSA cover tape that is peeled off from the carrier tape during the assembly process. This application note describes the problem and provides a summary of precautions that can be used to prevent this unwanted effect from happening.

App note: How to avoid chipLEDs sticking to cover tape during automated tape-and-reel assembly

an_vishay_chipledsticking

Investigative app note from Vishay on preventing too light components from sticking on the cover tape of their reel. Link here (PDF)

Customers have informed Vishay that 0603 LEDs (ChipLEDs) supplied in tape and reel format sometimes stick to the PSA cover tape that is peeled off from the carrier tape during the assembly process. This application note describes the problem and provides a summary of precautions that can be used to prevent this unwanted effect from happening.

App note: A simple alternative to analog isolation amplifiers

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A linear isolation amplifier from Silicon Labs app note. Link here (PDF)

Analog circuits sometimes require linear (analog) signal isolation for safety, signal level shifting, and/or ground loop elimination. Linear signal isolation is typically difficult to implement, costly, and often exhibits mediocre performance. While the design community thirsts for a flexible and inexpensive linear isolator solution, it is the analog isolation amplifier (ISOamp) that most often captures the socket.

WBR-Oscar regen receiver

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A nice write-up on Sheldon’s (N6JJA) version of N1BYT’s WBR regenerative receiver:

This article is broken into two parts. First comes the “Oscar” preselector/preamplifier. As I said, I intended it to be either part of the overall receiver or used as a standalone where desired. The second part deals with the WBR upgrades. Both designs were built using the same techniques and I’ve tested both and found that—especially in concert—they do about as well as some of my boat anchors! So if your soldering iron is ready, I’ll start by describing “Oscar.”

Via Dave Richards AA7EE Blog.

Homebrew SDR HF transceiver

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Simonhk (G0FCU) wrote a series of posts on building homebrew SDR HF transceiver:

However, what you might notice is the presence of image products in the waterfall. The processing of the signal suppresses all but the very strongest of these so they don’t appear as audio but it is mighty confusing when they are on the waterfall but actually not there (if you see what I mean)!
I am in the process of building a QSD or Tayloe Detector, which should provide better rejection of images. I have breadboarded one of these, it works but not very well. I think that this might be due to the length of leads I have on the breadboard so I am trying to use Eagle CAD to design a circuit board to overcome these problems.

Check out the video after the break.

 

Guitar Amp builder notes — AF power amplifier dummy load

DSC_2129-1 (1)Vasily Ivanenko has written an article detailing his AF dummy load project:

I’ll describe a simple 8, or 4 Ω dummy load to test your home brew guitar power amplifiers.
Low cost 16 Ω / 25W wire wound, aluminum shell, chassis mount resistors seem abundant.  I got mine on eBay.  Wire wound resistors vary in quality, design and tolerance. Some even exhibit low inductance by winding with an Ayrton-Perry bifilar technique.  Resistor tolerances range from 10% down to ± 0.5 % + 0.05 Ω.  Typical manufacturer power ratings are done at 25C, however, these devices are meant to sit on a heat sink when used and that’s why the aluminum housing contains 2 relatively large mounting holes.

Project info on QRF HomeBuilder blog.

Building a direct conversion receiver

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Ryan Flowers over at MiscDotGeek posted a how-to on building a direct conversion receiver:

In the first installment of this series, we discussed why we’re building a Direct Conversion receiver and talked about some basic ideas. In this installment, we explore what it takes to make the leap from a printed schematic to something physical that works. Follow along!

More details at MiscDotGeek.com.

Arduino Yun, how to update to rev.2

This year in March, Massimo Banzi announced on the Arduino blog the production of a new revision (Rev.2) of the Arduino Yun board.

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In addition to some improvements on the hardware design, the new revision offers a complete update of the software side of the Yun, that is the Linux distribution (OpenWrt) running on the board. The original Yun was indeed stuck to a distribution released in 2014 (still available in the download section of Arduino website) and that distribution contained outdated software packages which also presented some security vulnerabilites.

Who now buy a new Yun board, has the new OS version pre-installed. If you own a “Rev.1″ board, in this article you’ll learn how to update it…

Updater

In the Arduino forum, Martino Facchin (one of the contributors of the OpenWrt porting to Yun) published a post with links to an automatic updater for the different platforms (Windows, Linux, Mac). The application updates both the bootloader and the operating system (rootfs). You have to also update the bootloader because of the new OS requires a bigger partition than the original one.

Before running the updater process, there are 3 prerequisites:

  • the Yun board must be connected both to your computer via USB and to your home router/switch using an ethernet cable (the update process cannot happen using wifi)
  • your computer, which runs the updater application, must be connected to the same home network the Yun is connected to
  • your computer must not run softwares (like firewalls) that could block incoming connections

The third point in particular is the one that can give more problems… for example I use the Eset Internet Security suite and I had to temporary disable the protection:

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An additional suggestion is to disable other network cards in your computer, keeping active only the one connected to the home network:

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If you’re using Windows 10, it may happen that the yun-go-updater.exe program is blocked… in this case you have to cancel the block from the file properties:

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If you run the program, the update process should go automatically. When complete, if you connect to the Yun board you should see the new version:

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DHCP

During the update process, the Yun board requests a valid IP address for your network using the DHCP protocol. Sometimes this request could fail; in this case you can assign a static IP to the board answering “n” to the first question:

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App note: Ambient light sensor SFH5701

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App note from OSRAM on their ALS device SFH5701, its operation and application method. Link here (PDF)

The SFH5701 is a small, two-wire, linear output current ambient light sensor (ALS) with current amplifier and dark current compensation. The ALS is capable of resolving a wide range of ambient light levels (10 mlx – 10 klx) tailored to the spectral response of the human eye and operational from -40 °C to 100 °C.