I had the opportunity last week to interview Murray Harms from Queensland Australia, and talk to him about his home made Iron Man Suit. He built it with his son for Halloween and as you can see below, it looks pretty amazing.
The NE555 was designed in 1970 by Hans Camenzind and to this day remains an incredibly versatile chip.
Entries are due March 1st and will be judged by Hans Camenzind and Forrest Mims. For more information, please go to http://www.555contest.com
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When you were a kid, you may have made a lemon battery for a school science project. These are very simple to make and involves inserting dissimilar metals into a lemon. Typical materials are copper staples and zinc plated nails. This combination usually gives you 0.7V and a few milliamps.
The chemical reaction that happens in a lemon battery is called "Galvanic corrosion" and it also happens when 2 dissimilar metals touch each other. For galvanic corrosion to occur, the following factors must be present:
Ever wanted to drive you etch-a-sketch from your computer, well one guy did and this is how he did it!
The concept is pretty straight forward. The interface to the notebook is via a parallel port, there are a pair of stepper motors that turn the knobs on the etch-a-sketch, and an ATMEGA8 sits in the middle.
One of the design challenges was that the stepper motors were rated at 24V and also drew a fair bit of current. A pair of uln2803 darlinton arrays were used with 2 channels used for each step. Each channel on the array can handle up to 500ma, so this provided adequate current for the motors.