# Monthly archives: March 2013

## Audio Amplifier

Today’s lab: Amplifier to drive a small speaker

http://www.erosenthal.com/NYUITP/Session_8.html

Works like a charm!

Posted in Basic Analog Circuit | Comments Off

## Experiments in Computation & Fashion

Experiment 1: Shapelock

Shapelock was a great material to experiment with. The material heats up quickly with a heatgun and becomes moldable. When I heated a pile of it up, I decided that I really liked the organic structure, look and feel of the pellets themselves so I used that to make a couple pieces and molded it to my body.

Experiment 2: Voronoi Cells

I used a processing script from Mark K. and Shieva R. as inspiration to generate voronoi forms and brought the geometry into Rhino. Final Step, Makerbot.

Posted in computation & fashion | Comments Off

## Do the harvestShake

Mary Fe, Maria Paula and I finally got our shake on! We learned that it is best to use thin copper wire wound very tightly and many many times to get the most voltage. The best coil we got can put out a max of 10 volts.

We soldered up a board with 6 LEDs, a bridge rectifier and 4 0.0047F capacitors in parallel to hold some of the charge.

Starting voltage: 0 V

Ending voltage:  8.5 V

Starting energy: 0 joules

end: (0.5) * 4 * (0.0047 F) * (8.5V) * (8.5V)= 0.68 Joules

power = 0.68/ 20 secs = 0.034 watts

## Shake it up

For our midterm project, we decided to make a wearable/mobile system that produces energy by either shaking or beating it.

First, we thought about using piezos, but they produced almost no current with high voltage peaks. Inspired by shake-lights, we proposed to build a shaking system with copper coil and a neodymium magnet passing through it.

Our first attempt was a failure. It produced something around 0.06V (60 mV) and 4 miliAmps. The problem was: the coil was too small. We needed a LOT more wire.

We tried other coils and started getting some more interesting numbers. The coil on the left in the first picture produced a bit more than 10V! The middle one 5V and the smallest reached 2.5V.

To calculate Power, we measured the voltage difference when charging up a capacitor. Doing the math, we reached the following numbers:

Starting voltage: 1.5V
Ending voltage: 6.5V
Capacitance: 4700 microF
Starting energy: 0.5 * (0.0047 F) * (6.5 V) * (6.5 V) = 0.0992875 joules
Ending energy: 0.5 * (0.0047 F) * (1.5 V) * (1.5 V) = 0.0052875 joules
Difference: 0.0992875 – 0.0052875 = 0.094 joules
Time: 3 secs
Power: 0.031 Watts

Posted in Energy | Comments Off

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