DIY photoplethysmographic pulse sensor


Raj has posted a tutorial about a DIY photoplethysmographic sensor for measuring heart rate from fingertip. “The sensor measures the little variations in the blood volume inside finger tissue and outputs a digital pulse which is synchronous with the heart beat.” The sensor used in this project is TCRT1000, which is a reflective optical sensor with both the infrared light emitter and phototransistor. The sensors output goes through several stages of signal conditioning using a MCP6004 op amp before its fed into an oscilloscope or similar device.

You can find the schemtic and other project info in Raj’s post on EmbeddedLab.

Via the contact form.

Little Wire Python library

Adam ported Little Wire’s library to Python. The library was already available in C, C++, and Processing, and now Python users can enjoy the little hack tool as well.

Little Wire is multi-featured USB controlled open source hardware tool packed in a minimal form factor designed by Ihsan Kehribar. Even though it has minimal form factor, it’s packed with full of features. There aren’t any SMT components involved, so it is very suitable for beginners to assemble.

Ishan donated 2 of them to the open 7400 Logic Competition.

Via the forum.

DIY flux made from pine gum straight from the tree

We’ve posted about homemade flux before, but Tom has taken it to a whole new level. He used pine gum straight from the tree for his Flux recipe. He dissolved the rosin in some 99% isopropyl alcohol, and filtered it using coffee filters.

I tried making flux from an even more raw material, pine gum straight from the tree. It had to be filtered, of course, but so far so good — and the turpentine in it hasn’t eaten through my bottle yet. :)

Via the forum.

NEXT WEEK: New York City East Village food crawl 2012

Last year we failed to discover a New York City equivalent of the Mission District taco crawl. In 2012 we’re trying several different stand-and-eat joints in the East Village.

The crawl will kick off on Wednesday evening, September 27th, somewhere in the East Village. The exact time and meeting place is yet to be decided. If you’re interested in joining please contact us.

Stops
The exact route is yet to be decided, but here are the places we’re looking to visit.

Continue reading “NEXT WEEK: New York City East Village food crawl 2012”

NEXT WEEK: New York Global Geek Tour 2012

Next week we are heading for the World Maker Faire 2012 held in New York. We’ll also be attending the Open Hardware Summit 2012 during the same week to give a presentation on USB and open hardware.

As always we try to plan some trip to local electronics shop, and eat some great stuff along the way. We’ll be hitting the East Village for an evening food crawl, and visiting some electronics shops in Manhattan and Brooklyn. If you’re in New York for the festivities and would like to join, please hit us up over the contact form for more details.

Locations

Here’s some electronics shops and hackerspaces to visit the day between the Open Hardware Summit and the Maker Faire. This is by no means south east Asia, but it’s good for an afternoon out.

  • Hack Manhattan hackerspace – A good meeting point
  • Radio Shack @ 781 Broadway near NYU – Supposed to have the best selection of parts and Arduinos
  • 269 Electronics – Soldering supplies and kits, tools, some parts, HAM Radio stuff. No surface mount parts
  • Argo Electronics – Used gear, surplus parts, connectors, mostly junk
  • Leeds Radio in Brooklyn – Tubes, connectors, enclosures, switches. Stop at Brooklyn Brewery on the way (see food map layer)

These are all saved to a Google Maps layer so you can take them with you on your own tour.

We usually end at the Maker Faire setup party in Brooklyn. You generally need to be a registered maker to get in, but sometimes there’s extra passes or a lenient gate operator.

Food Crawl

Thus far we’ve failed to discover a New York City equivalent of the Mission District. In 2011 we failed to crawl, but in 2012 we’re trying a several different stand-and-eat joints in the East Village. We’ll post more information about the East Village food crawl later today.

Eagle Parts: Our Eagle library converted to KiCad

Lately we’ve been testing the KiCad waters. For the ATX Breakout Board v2 we needed to escape Eagle’s PCB constraints, and we succeed.

A major hurdle to using any new CAD package is that all your part libraries have to be built again.

Luckily Sjaak pointed us to a script that helps you convert your library from Eagle to KiCad. We did hit a tiny snag in the conversion. All the squared pin 1 pins in the Eagle parts get converted with an error on that pin in KiCad. This is a small error compared with building each part from scratch.

You can get our KiCad library from the SVN. Keep in mind we are just messing around with KiCad, there’s a ton of bugs in there we don’t know about.

Tuitwall displays Tweets on LED matrix


tuitwall is a project that will allow you to show Tweets in a LED matrix. It’s based on an Arduino, an ethernet shield, a LED matrix that has its controller, a Holtek HT1632C and a PHP backend that interfaces with Twitter. Its designer Santiago Reig explains: “The webpage, written in PHP, allows a user to login with their Twitter account and show their Tweets in the LED matrix. It also shows the status, as the last Tweet shown, logged user, type of Tweets (timeline, mentions, your own ones) and optionally a video stream. There is a configuration file, so lots of things can be tweaked to your liking or needs.
Continue reading “Tuitwall displays Tweets on LED matrix”

#FreePCB via Twitter to 2 random RTs

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.

Workshop Update for September 17th, 2012

We’re finishing up Geek Tour schedules, especially New York. We’ll be posting schedules for the East Village food crawl and geek tours tomorrow if you’d like to join us. We got our first complete nixie thing module running.

Modeled and rendered the Bus Blaster v3 in the SoB case model for today’s post. We also worked on illustrating the Open Hardware Summit 2012 open USB presentation.

We made a small adjustment to the Bus Pirate Demo Board silk. Working on a holder board for a NEC D-8035-E VFD tube.

Open 7400 prize: C2000 Piccolo LaunchPad from C2kCentral forum

C2kCentral forum donated a C2000 Piccolo LaunchPad- LAUNCHXL F28027 to the Open 7400 Logic Competition. Get your entry in and this and other cool hardware can be yours.

The C2000 Piccolo LaunchPad is an inexpensive evaluation platform designed to help you leap right into the world of real-time control programming on the C2000 Piccolo microcontrollers. The LaunchPad is based on the Piccolo TMS320F28027 with unique features such as 64KB of on board flash, 8 PWM channels, eCAP, 12bit ADC, I2C, SPI, UART, and much more.

Thank you to C2kCentral forum for sponsoring the 2012 Open 7400 Logic Competition!

More projects using Altoids tin boxes as enclosures

In response to our “Disposable metal boxes make excellent shielded enclosures” app note post, Sverre shared some of his projects using the same enclosures. They are mostly RF projects, benefiting from the tin enclosure’s EMF protection.

Nice post which triggered me to picture some of my own Altoid projects.

Via the comments.

GNU Radio internals – how to use the framework


The availability of inexpensive SDR hardware such as the RTL-SDR and Funcube Dongle help to focus interest on the GNU Radio open source signal processing software. In this video from CCC Camp 2011 Marius Ciepluch delivers a case-study on how to analyze 802.15.4 (alias Zigbee) with USRPs on a real-time protocol (for send time verification, sniffing etc.). Marius attempts to explain the internals of DSP in simple terms for non-experts using demos analyzing ISM band signals.

3D Model: Bus Blaster v3 in a Sick of Beige v1 case

Today’s 3D model is the Bus Blaster v3c in our  Sick of Beige v1 enclosure. The Bus Blaster is a high-speed JTAG debugger for ARM processors, FPGAs, CPLDs, flash, and more. The v3 is a PCB, and part placement change only. The electrical connections are identical to the Bus Blaster v2.

Get a Bus Blaster v2 for $34.95.

In version 3 we moved the Bus Blaster to the new standard PCB size DP8049, and the parts have been repositioned, with the USB, the FT2232H, CPLD, and the shrouded header all placed inline from left to right.

The models will be published in the Dangerous Prototypes 3D warehouse collection. They are also uploaded to our SVN. You can find them inside the “art” folders in the respective project folders. Check out the 3D view below. You can zoom and rotate the model.

You can get a Bus Blaster v2 for $34.95.

7 segment display controlled by simple SPI interface

Touch let us know about these 4 digit SPI controlled 7 segment displays that cost a little less then $1 a piece. They include decimal separators and a colon separator so it’s easy to display time.

I picked up some cheap 4 digit 7 segment displays over on eBay for $10 + shipping. They Include a SPI PT6961 driver chip built in that deals with PWM and Multiplexing, saves on microcontroller ports & current limiting resistors. Figured someone here may have a use for them!

Via the forum.

DimBlue – USB controllable 16 channel light dimmer

Matseng designed DimBlue, an ATmega32u4 based USB controllable 16 channel light dimmer. Triacs which dim the lights are optoisolated from mains to provide protection from high voltages. The board is powered from mains voltage, via a PCB mounted transformer.

As an added bonus, the board has a footprint for a serial Bluetooth module, giving it the possibility of wireless control.

Via the forum.