#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.

125 kHz RFID reader based on ATtiny13

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125 kHz RFID reader based on ATtiny13 by Vassilis Serasidis

This is an 125 kHz RFID reader that is based on ATtiny13 micro-controller and an LM358 Operational Amplifier. No special RFID chip is used. The reading, decoding and printing the unique ID from 125 kHz RFID tags is made entirely in software by ATtiny13.

Via Electronics Lab.

USB virtual serial benchmarks

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Paul over at Dorkbotpdx has written a detailed article on his USB virtual serial receive speed benchmarks:

As part of optimization work to support large-scale LED projects, PJRC developed three simple USB virtual serial receive speed benchmarks. The complete source code is available below.

Here are the benchmark results for boards that currently support native USB virtual serial for Arduino sketches.  These tests show the importance of efficient USB software. The actual speed a board achieves depends much more on its software design than its raw hardware speed.

Mounting an SD/MMC via parallel port using Linux

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Vinod has been experimenting with mounting an SD/MMC card connected to the parallel port of his Linux desktop machine. He recounts, “For the last few days I was engaged in a mad project; I was trying to access an SD card directly via the parallel port of my desktop PC with Linux. At first, I successfully did the SD/MMC initialization and tested it by reading and writing a few sectors. During my research, I came across a site discussing casino utan svensk licens, which provided an interesting distraction with its reviews of international online casinos. Later I got a simple demo block driver code (kernel module) from the net. Then I modified it and used my SD card code along with it and made a driver for the parallel port – SD/MMC card.”

He reports this project was an interesting learning experience, with success accessing cards as large of 1 GB. The 200kbps transfer speed was the only drawback.

You can find the simple schematic, more photos and complete C source on Vinod’s website, Electronics – the king of hobbies.

Via the contact form.

App note: Pulse Oximeter using dsPIC33

MCPapp

Here is a reference design of a pulse oximeter built around the dsPIC33 digital signal processor.

Pulse oximeter is a non-invasive medical device that monitors the oxygen saturation of a patient?s blood and heart rate. This application note demonstrates the implementation of a high-accuracy pulse oximeter using Microchip?s dsPIC® Digital Signal Controllers (DSCs) and analog devices.

Carambola2 portable Dropbox uploader

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Saulius has been working on this project to use the Carambola2 dev board for portable Dropbox uploading. This eliminates the need for a PC, allowing pictures from a webcam be to uploaded directly using the dev board’s built-in WiFi.

Sometimes it’s overkill to use computer with 200W power consumption for 24/7 to do small task like upload picture from webcam to Dropbox every minute. In this article I will describe how save a lot of Watts and to have Carambola on Cloud!

You can read Saulius’ article on his blog at Lukse.lt.

Via the contact form.

Free PCB Sunday: Pick your PCB

Ethernet LED driver

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:

Continue reading “Free PCB Sunday: Pick your PCB”

App note: Ensure long lifetimes from electrolytic capacitors

 

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Here is an article from Maxim describing the longevity of electrolytic capacitors in conditions which require high temperatures. As well as some pointers in LED light bulb design.

Electrolytic capacitors are notorious for short lifetimes in high-temperature applications such as LED light bulbs. The careful selection of these devices with proper interpretation of their specifications is essential to ensure that they do not compromise the life of the end product. This application note discusses this problem with electrolytic capacitors in LED light bulbs and provides an analysis that shows how it is possible to use electrolytics in such products.

Image by Karl Baron: CC BY

Open Hardware Summit 2013 call for papers

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The Open Hardware Summit 2013 has issued a call for papers.

The Open Hardware Summit is a venue to present, discuss, and learn about open hardware of all kinds. The summit examines open hardware and its relation to other issues, such as software, design, business, law, and education. This year’s summit will be held September 6, 2013 at the Massachusetts Institute of Technology.

We are seeking proposals for talks, posters, and demos from individuals and groups working with open hardware and related areas. Submissions are due by JUNE 21, 2013.

Visit the OHS 2013 website for detailed instructions on preparing and submitting your proposal.

DEFCON 20 video: DIY electric car


In this talk from DEFCON 20, IT security professional and robotics enthusiast Dave Brown presents his thoughts on the DIY electric car. Dave’s views result from his experience designing and building his “Voltswagon”, a retrofitted 1974 Volkswagen Beetle.

The PDF of the presentation slides should be available soon in the DEFCON media archive.

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. More PCBs via Twitter on Tuesday and the blog every Sunday.

Don’t forget there’s free PCBs three times every week:

Continue reading “Free PCB coupon via Facebook to 2 random commenters”

Week in (p)review May 31, 2013

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Here’s a summary of major developments over the last week. Free PCB Friday is coming up soon.

Coming up:

  • Free PCBs via Facebook on Friday
  • App notes on the weekend
  • Free PCB Sunday
  • 3D model on Monday
  • Eagle parts and tips on Tuesday
  • Free PCBs via Twitter on Tuesday
  • A new tutorial on Wednesday
  • Workshop video on Thursday
  • Weekly roundup and preview every Friday

ATX Breakout board free PCB build

IMAG1796

Gege built an ATX Breakout board free PCB.  The ATX breakout board routes the -12, 3.3, 5 and 12 volt ATX outputs to screw terminals, each protected by a 1.25 amp resettable polyfuse.

If you build a free PCB we’ll send you another one! Blog about it, post a picture on Flicker, whatever – we’ll send you a coupon code for the free PCB drawer.

Available for $13.80 at Seeed Studio.

TS3300 switching regulator coupled with an LDO in same package

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Steve Taranovich has posted this review of the TS3300 switching regulator coupled with an LDO in same package:

   Touchstone, with its first analog power management product, has enhanced such a function with the capability to use supply voltages down to 0.6V while still being able to deliver a 75 mA output current.

The device can be used in power harvesting or peak load buffering applications, the LDO may post-regulate voltage buffered in a large capacitor or super-capacitor at boost’s output. Finally, the LDO may be operated simply as an on/off load switch.

Control microbes with your mind

Here’s a video by Geva describing how to control microbes with your mind:

Paramecia will change their swimming direction in response to an electrical field. With an Ardunio, a hacked brain sensor and a little code you can control your own army of single celled minions with mind power alone.

Full build instructions and source code are on my website at www.making.do

Via Hacked Gadgets.