Electronics

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16
November
2011

Real-time DAQ system

The problem: Creating a low-cost 4-channel simultaneous DAQ accurate to 4 microseconds

The solution: Using four slave microcontrollers synchronized by a master controller, each sampling a single ADC channel at ~77kHz.


One really exciting thing we can do with a real-time DAQ is essentially make a touchscreen. Imagine a scenario where we have four accelerometers or piezoelectric vibration sensors, arranged in a rectangular (or square) configuration and mounted on a sheet of homogeneous material. If something strikes anywhere in the middle of the rectangle, the vibrations will propagate in all directions at the same speed, reaching each accelerometer at slightly different times based on where the strike was located. By using our real-time DAQ to find these exact times, we can use some clever math to figure out the exact location of the impact!


In order to do this, we first need to find the phase delay between two accelerometers, which can be calculated by subtracting the start times from one another.

If instead of looking at our coordinate system in units of distance we look at it in terms of seconds, we can treat the phase delay as our impact location. For example, if we were to strike the exact center of the board the impact would reach both accelerometers of each axis at exactly the same time, and the X and Y delays would measure zero - thus giving a coordinate of (0,0).


Read more to see how it works and what I'm planning on doing with this system!

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27
December
2010

RFID Adventures

This was a quick project I put together on the side when I was learning (teaching myself) about RFID theory. This project uses an Arduino and a Parallax RFID module to read an RFID tag and grant access if it's the correct one. This could easily be expanded to the classic RFID experiment of actuating a door lock to unlock a door if the correct RFID tag is swiped.



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25
December
2010

CNC control board

Merry Christmas to me! Today I assembled an EZ driver board from Hobby CNC. Yep, you guessed correctly - I'm planning on building my own CNC mill. My plan at this point is to build something capable of milling foam, which I can then cast into aluminum using lost foam techniques with my home foundry!