Tuesday, 23 April 2013

Hack A day: Pulse Oximeter from LM324, LED, and Photodiode

From Hackady: "This pulse oximeter is so simple and cheap to build it’s almost criminal. The most obvious way to monitor the output of the sensor is to use an oscilloscope. The poor-man’s stand-in for that is a sound card, which is what [Scott Harden] demonstrates in his write-up.
It uses a concept we’ve seen a few times before. The light from an LED shines through your finger and is measured on the other side by a phototransistor. It’s that light grey plastic thing you see on a patient’s finger when they’re in the hospital. [Scott] went with a common wooden clothes pin as a way to mount and align the sensor with your finger. It is monitored by the simplest of circuits which uses just one chip: an LM324 op-amp. There are three basic stages which he explains well in the video after the jump. The incoming signal is decoupled before being fed to the first amplifier stage. From there it is fed to an adjustable low-pass filter to help eliminate 60Hz noise from AC power in the room. The last stage amplifies the signal again while using another low-pass filter in parallel."
[From Hack A Day]

Make: BeagleBone Black Has Arrived

A new version of the BeagleBone is available, and from the name, Black, you might be forgiven for thinking that its got carbon fibre components, low profile wheels and it's weight has been reduced by getting rid of all unnecessary luxuries (Car joke BTW).
But no, all this has lost is the ability to reflect colored light, and replaced them with some stunning new features
  • The CPU runs at1GHz, up from the original’s 720MHz.
  • RAM doubled to 512MB.
  • Connection to an HDMI monitor through the on-board MicroHDMI port.
  • 2GB of on-board flash memory, which will be loaded with the Ångström Linux. You can overwrite this, and still get the micro-sd option.
  • The OS has been upgraded to Linux Kernel 3.8 and included upgrades to Java and the disk software.
This is all very good, I have been keeping the best until last, which is the price has dropped to $45 bringing it into direct competition with the Raspberry PI. And with that on-board OS Flash I think it might have just crept into the lead.

Make: 200,000 Piece Lego Sci-Fi Jaw Dropper

From Make "New York-based graphic designer and artist Mike Doyle caught our attention a couple of years ago with his beautifully rendered eerie Lego Victorian houses. His latest piece, titled Contact 1, employs over 200,000 Lego bricks, took him over 600 hours to build, and stands 5 feet tall and 6 feet wide. Contact 1 is the first in a series Doyle is working on, and he writes, “The Contact Series of Lego-built creations was designed to promote the beauty of all intelligent life forms as extensions of our family – children under the same creative force.”
The images seem unreal, leaving the viewer wondering if they are of an actual sculpture or a rendering. Doyle responds, “The project is built and then photographed. 90% of the saucers are connected to the model with black Lego hoses. These mostly disappeared against a black screen. Those hoses that remained, I darkened to disappear. For some of the saucers appearing in front of the buildings, they were attached and then the attachments photoshopped out for a cleaner presentation.”
For full article go to http://blog.makezine.com/2013/04/22/200000-piece-lego-sci-fi-jaw-dropper/]