LED resistor calculator

This calculates the number of ohms needed in a resistor when connecting one or more LEDs to a power source.

CDF file test

Move slider to change x

Image Processing

Original image

ImageReflect

Grayscale

Binarize

ColorNegate

ColorQuantize

When Sigma equals .07

LaplacianFilter

Created using Mathematica

9V USB Charger and Flashlight

This is a project that I have been working on for a few days. Made completely out of scratch. It is powered by a 9 volt battery, and can charge USB devices (including  the iPhone) and also has two blue 5mm LED's for a flashlight. Uses the 7805 voltage converter to bring down the 9 volts to 5 volts. The converter can get hot, so I added a mini heat sink I made out of copper enameled wire (not in photo). Two switches, one for converter, one for the LED's. The whole project fits nicely in an Altoids tin. 

Drilled away hole for female USB port then cut it away with tin snips.
Soldered onto the can.

Two switches, one for converter and one for LED.

Messy wiring. 

Charging an iPhone 4

Can light up a small white room easily.

Project idea credit goes to matt.e.jenkins.
If you want my specific schematic and more details, just email me.

USA vs. Mexico Population

Equation for USA is 1.8638^8 * 1.0114^x + 1.8517^7
Equation for Mexico is 9.8287^8 * 1.0015^x + -9.2925^8

Estimated Population in 2020 is 3.46757 x 10^8 and 1.28978 x 10^8

Estimated Population in 2050 is 4.79483 x 10^8 and 1.76944*10^8

Estimated Population in 2100 is 8.30344 x 10^8 and 2.61766 x 10^8

Infant Mortality Rate vs. Total Fertility Rate

This graph shows that the total fertility rate decreases with the infant mortality rate.

Created using Mathematica.

Functions and Regression Starbucks

Logistic Regression Graph when a = 375.065, b = 0.332098, c = 20499
20499/(1 + 375.065 E^(-0.332098 x))

In year 33, 2020, the expected number of Starbucks stores
 according to the equation is about 20366 stores.

In year 43, 2030, the expected number of Starbucks stores
 according to the equation is about 20494 stores. 

Created Using Mathematica