Free PCB Sunday: Pick your PCB

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We go through a lot of prototype PCBs, and end up with lots of extras that we’ll never use. Every Sunday we give away a few PCBs from one of our past or future projects, or a related prototype. Our PCBs are made through Seeed Studio’s Fusion board service. This week two random commenters will get a coupon code for the free PCB drawer tomorrow morning. Pick your own PCB. You get unlimited free PCBs now – finish one and we’ll send you another! Don’t forget there’s free PCBs three times every week:

Some stuff:

  • Yes, we’ll mail it anywhere in the world!
  • Be sure to use a real e-mail in the address field so we can contact you with the coupon.
  • Limit one PCB per address per month please.
  • Like everything else on this site, PCBs are offered without warranty.
  • PCBs are scrap and have no value, due to limited supply it is not possible to replace a board lost in the post

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App note: Aluminum electrolytic capacitors design for long operational life

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App note from KEMET on long life electrolytic capacitors. Link here (PDF)

The service life for high quality power supplies and automotive power electronics is often limited by electrolytic capacitors’ operational life (Lop). Very long life (> 20 years at temperature up to 75C) is possible to be achieved by choosing capacitors with optimized design. Type of electrolyte, capacitors lid design, sealing method and rubber material quality, are important factors which determine the Lop.

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App note: Comparison of ceramic and tantalum capacitors

 

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App note from KEMET about the replaceability between ceramic and tantalum capacitors to each other. Link here (PDF)

Ceramic capacitors have a multitude of dielectric types available and each of these types is characterized by their sensitivities to temparature, but not to voltage or time. This paper compares the X7R, X6S, or X5R dielectric types of ceramic capacitors with tantalum capacitors. Ceramic capacitors constructed witht these dielectrics offer moderate dielectric constants with moderate temperature and voltage sensitivities. They overlap with tantalum capacitors in capacitance/voltage range offerings. In many cases, the solder pad geometry allows swapping of ceramic 0603. 0805, 1206 or 1210 chip sizes with “J”, “R”, “A”, or “B” case tantalums, respectively.

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Video tutorials: Building the Arduino based data loggers

From the comments on our Arduino data logger post:

A visiting researcher dropped by our humble basement workshop with questions about the physical skill level students would need if they added one of our DIY data loggers to their environmental curriculum. I figured the easiest way to cover that was to simply build one, while they recorded the process.
The result of that 3 hour session is now available on YouTube

Thanks Edward Mallon!

Project info at the Cave Pearl Project website.

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STM32F103 vs GD32F103 round 4: SPI master

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Sjaak writes, “This is part 4 in the series where we compare the STM32F103 with its Chinese counterpart the GD32F103. Both are ARM Cortex M3 microcontrollers which are mostly pin, peripheral and register compatible. Now we compare the SPI master peripheral of both chips.”

More details at smdprutser.nl.

Check out the video after the break. 

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Free PCB coupon via Facebook to 2 random commenters

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Every Friday we give away some extra PCBs via Facebook. This post was announced on Facebook, and on Monday we’ll send coupon codes to two random commenters. The coupon code usually go to Facebook ‘Other’ Messages Folder . More PCBs via Twitter on Tuesday and the blog every Sunday. Don’t forget there’s free PCBs three times every week:

Some stuff:

  • Yes, we’ll mail it anywhere in the world!
  • We’ll contact you via Facebook 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.

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Building a GBA LiPo voltage regulator and charger

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Alex published a new build:

I saw a post where someone fitted a 2000mAh LiPo battery to their GBA, they had do to some modifications to the GBA battery compartment to fit it all. By using a LiPo battery instead of the AA’s, it would save us about 20 grams, while not a lot, ever gram does count and you can tell the difference plus since the LiPo has a higher voltage, it has a higher energy density, so it should give us longer play time than the AA’s. So I decided I would do the same mod and I might make a little voltage regulator and charging board to go along with it.

See the full post on insideGadgets project page.

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A software only solution to the vexing beagle bone black PHY issue

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Josh Levine has a nice write-up about a software only workaround for the Beagle Bone Black PHY issue:

Sometimes the Ethernet port on a Beagle Bone Black does not work on power up. It takes either a physical reset button press or a power cycle to fix it. This problem affects all BBB’s and until now could only be solved with hardware hacks.

The final official word from TI on this problem:
“There is no solution for this on the BB Black“

Full details at josh.com.

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Tutorial: Setting up a low cost QRP (FT8, JT9, WSPR etc) monitoring station with an RTL-SDR v3 and Raspberry pi 3

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A detailed tutorial on how to set up a cheap QRP monitoring station using an RTL-SDR V3 and a Raspberry Pi 3 from rtl-sdr.com

This tutorial is inspired by dg0opk’s videos and blog post on monitoring QRP with single board computers. We’ll show you how to set up a super cheap QRP monitoring station using an RTL-SDR V3 and a Raspberry Pi 3. The total cost should be about US $56 ($21 for the RTL-SDR V3, and $35 for the Pi 3).
With this setup you’ll be able to continuously monitor multiple modes within the same band simultaneously (e.g. monitor 20 meter FT8, JT65+JT9 and WSPR all on one dongle at the same time). The method for creating multiple channels in Linux may also be useful for other applications. If you happen to have an upconverter or a better SDR to dedicate to monitoring such as an SDRplay or an Airspy HF+, then this can substitute for the RTL-SDR V3 as well.

More details at rtl-sdr.com.

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