Square Root of Not

In a previous article, I demonstrate how to build an alcohol burner for a home chemistry set. In my article, I mention that "second-hand stores like Goodwill, Salvation Army, and local mom&pop shops are treasure troves of things to hack or repurpose." I would like to mention too that close-out stores like Dollar General are also fertile ground for modding.

Direct current (DC)

In a DC (direct current) circuit where the electricity flows in one direction, we can think of a battery as a storage tank like the water tower in your neighborhood. If nobody turned on their faucet, the water in the tower would just sit there. Forever. Physicists like to think of this as "potential energy." Like a boulder at the top of a hill, it will just sit there, forever, until someone pushes it over the hill or an earthquake shakes it from the top of the hill or erosion undermines it starting it to roll down the hill. When the boulder is rolling down the hill, physicists like to think of this as kinetic energy. So, the water will just sit in the top of the water tower until you turn on the faucet to your water hose.

Second-hand stores like Goodwill, Salvation Army, and local mom&pop shops are treasure troves of things to hack or repurpose. When you hack something you’re probably using it in a way in which it was never intended to be used so, there is always a risk that things might not go the way you planned. But since you can get items from second-hand stores on the cheap, you don’t care too much if you are disappointed with the results. Luckily, this "MacGyverism" was successful.

When we say "off the grid," we often mean off the power grid.

In honor of

National Robotics Week 2013
(April 6-14) I am adding this article that I originally posted on my

Society of Robots

blog page.

In this article you will learn how to build a programmable Snap Circuits Rover by adding a PICAXE micro controller.

In my previous blog post,

Introduction to the 555 Timer IC

, you learned how to build an optical Theremin using a 555 Timer. The original Theremin used radio frequency interference caused by the movement of the player's hand to change the pitch of the instrument. The optical Theremin depends on the intensity of light that falls on a photo resistor also controlled by the movement of the player's hand.

The amount of light that fell on the photo resistor changed the resistance in the circuit. When more light fell on the photo resistor, it reduced the resistance in the circuit and this made the pitch higher. Less light increased the resistance and made the pitch lower.