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Physical Computing
Implantable RFID temperature sensors
Written by the machinegeek   
Friday, 28 January 2011 00:00

Authors: the machinegeek

Implantable RFID chips have been around for years. Since at least 2004 these devices have been capable of including GPS data, and manufacturers have been researching other measurement capabilities.

Implantable health sensors may soon be a real option with the launch by PositiveID of its ‘Wireless Body Platform’. Initially the health sensor system was designed for diabetics allowing blood sugar levels to be wirelessly read and sent to an external device. Now they have announced the ability to measure body temperature as well. The temperature sensing chip notifies people or their caregivers of rising body temperature giving them time to take anti viral medication which works best when taken early.

Three of PositiveID’s new sensors can be viewed here. Makes you wonder when chips will be able to monitor enough parameters to function as an implantable lie detector.

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Last Updated on Friday, 28 January 2011 04:01
How to make an H-bridge
Written by Administrator   
Thursday, 30 December 2010 00:00


Via Instructables.

An H-bridge is a type of circuit that you can use to get a reversible DC motor to spin both clockwise and counterclockwise.
In other words, this circuit allows you to quickly reverse the direction a motor is spinning by using a switch or controller chip to change its direction.

It's really handy to know how to control motors for a lot of Physical Computing and Robotics projects.

Last Updated on Thursday, 30 December 2010 01:39
Computer-controlled frypan for surface mount soldering
Written by admin   
Wednesday, 29 December 2010 00:00

Authors: admin

This project shows how to use a frypan for surface mount soldering. It uses a thermistor sensor to measure the frypan temperature and a solid state relay to control it. The overall device is controlled by an Arduino. To gain fine control of temperature the relay is controlling the heating element on and off. It’s something like low-frequency Pulse Width Modulation.  [via]

Last Updated on Tuesday, 28 December 2010 22:47
VFD tube counter v0.2
Written by blog   
Tuesday, 28 December 2010 00:00

Authors: blog


I have a new build of the VFD tube email counter which improves several aspects of the original:

  • replaced atmega8 microcontroller with smaller attiny2313
  • replaced IRF730 power mosfet with smaller IRFD110
  • replaced 100uH inductor with larger 2200uH inductor
  • replaced $20 FTDI USB-serial cable with $2 PL2303 cable
  • replaced boring old white breadboard with fancy new transparent breadboard
  • replaced ugly breadboard wires with shiny magwire

However, by far the biggest change is the elimination of 7 transistors. The first design used the conventional high-side switch arrangement of a level-shifting NPN to switch a PNP driving each segment anode, but it bothered me that Jon Stanley was able to get his single-tube clock working without the level-shifting NPNs. Now, Jon's clock is operating at a lower voltage than mine, and he's using a PIC instead of an AVR, so I wasn't sure if I could make that work. It seems that compensating for the higher voltage with a bigger base resistor works just fine so far.

If it continues to work well, I'll put it on a circuit board and make a nice aluminum case for it, like this one.

by coreylcoreyl

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Last Updated on Tuesday, 28 December 2010 22:31
Arduino based Water Tank Depth Sensor
Written by admin   
Tuesday, 28 December 2010 00:00

Authors: admin

This project is Arduino based water tank level indicator. It uses a device called a differential pressure transducer to measure the water pressure at the bottom of the tank, and from that to calculate how full the tank is. Water pressure increases by about 9.8067kPa per meter of depth so a full tank 2m tall will have a pressure at the bottom of about 19.6134kPa above ambient atmospheric pressure. [via]

Last Updated on Tuesday, 28 December 2010 22:44
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