Autor: sduro

Kevin Darrah writes:

The trigBoard is an IoT project that does one thing – it pushes you a notification triggered by a digital input. Well, it’s much more than that, but this is the inspiration. I wanted to design a WiFi board that essentially sleeps most of its life, but when that door switch, flood sensor, motion sensor, etc.. gets triggered, I just want a notification immediately on my phone. And that’s about it… a perfect IoT device in the background doing its job.

Project info on Kevin Darrah Wiki. It’s also up on Tindie.

Check out the video after the break.

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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.

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Michael Krumpus designed and built a SAMD21 development board with LoRa radio module and GPS receiver, that is available on GitHub:

I’ve been doing some LoRa projects lately in order to learn as much as I can about this exciting new radio technology (see this LoRa mesh networking project and this LoRa weather station). ATmega328-based Moteino modules work great for a lot of projects, but I wanted a LoRa node with more processing power, more memory, and an onboard GPS receiver. The ATmega328 is just too constrained with memory — I’ve outgrown it. I really wanted a LoRa board with an ARM Cortex microcontroller like the SAMD21. This is the microcontroller used on the Arduino Zero. So, my ideal board is a SAMD21 with LoRa radio module and GPS receiver, all programmable with the Arduino IDE.
But, where is such a board? I could not find one so I decided to design and make one myself.

More details on Project Lab.

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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:

• Tweet-a-PCB Tuesday. Follow us and get boards in 144 characters or less
• Facebook PCB Friday. Free PCBs while you wait for the weekend
• Free PCB Sunday, right here on the blog
• Check out how we mail PCBs worldwide

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

Be the first to comment, subscribe to the RSS feed.

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App note from Coilcraft on the design and construction of common mode filter inductor. Link here (PDF)

Noise limits set by regulatory agencies make solutions to common mode EMI a necessary consideration in the manufacture and use of electronic equipment. Common mode filters are generally relied upon to suppress line conducted common mode interference. When properly designed, these filters successfully and reliably reduce common mode noise. However, successful design of common mode filters requires foresight into the nonideal character of filter components — the inductor in particular. It is the aim of this paper to provide filter designers the knowledge required to identify those characteristics critical to desired filter performance.

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Coilcraft’s app note on temperature rise due to losses on inductors and transformers. Link here (PDF)

Core and winding losses in inductors and transformers cause a temperature rise whenever current flows through a winding. These losses are limited either by the allowed total loss for the application (power budget) or the maximum allowable temperature rise.

For example, many Coilcraft products are designed for an 85°C ambient environment and a 40°C temperature rise implying a maximum part temperature of +125°C. In general, the maximum allowed part temperature is the maximum ambient temperature plus temperature rise. If the losses that result in the maximum allowed part temperature meet the power budget limits, the component is considered acceptable for the application.

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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:

• Free PCB Sunday. The classic. Every week, get free PCBs right here on the blog comments
• Tweet-a-PCB Tuesday. Follow us and get boards in 144 characters or less
• Facebook PCB Friday. Free PCBs while you wait for the weekend
• Check out our video on how we mail PCBs worldwide.

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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Pete Juliano, N6QW,  has a nice build log on his newest version Heathkit 40M SSB Transceiver:

What are you thinking — I am not trying to break any world record? My XYL asked me that question today — why are you building another rig? Followed up by a snide comment that I had so many rigs now why do I need another one. Well the answer plain and simple because I can!
For the longest time in the late 60’s early 70’s my success rate with homebrew SSB transceivers was miserable. At that time I lacked the more sophisticated test gear and let’s face it some of the technology wasn’t that great. Crappy Analog VFO’s were high on the list of impediments! I also had to work and to give a fair share of my time to the family — it is that balance thing.
But today that is all changed –better test gear, better technology like Digital VFO’s and a bit more time. The latest project is to demonstrate that some of the components out of boat anchors can indeed be reworked to provide a very modern, very capable rig.

See the full post on N6QW blog.

Check out the video after the break.

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Technovative writes, “The purpose of this article, is to show a simple method to increase the power efficiency, and functionality, of standard DC actuated electromagnetic relay switches.”

Project instructables here.

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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.

from Dangerous Prototypes https://ift.tt/2CRUHOf