Perhaps one day soon we’ll have a battery that displays no “memory” effect; can be completely discharged or overcharged without harm; and require no complex computerized management system. Does such a battery sound like too much to hope for? Thomas Edison didn’t think so.
An open garage door is an invitation for thieves and vandals. And don’t forget the mischief birds, cats, raccoons, and other animals can cause in your garage. No problem! This handy device will close it automatically for you.
This article shows you how to build a really cool 3D cube with a 4 x 4 x 4 monochromatic LED matrix which has a total of 64 LEDs.
This alternative energy project is two-fold. First, convert a two-cycle engine to run on pressure (air/steam). Then, create a control system to optimize engine performance. This project is very easily reproduced by any experimenter with average mechanical skills; the controller is an easy breadboard; and — best of all — it’s cheap and green!
As an experimenter, I use wall warts all the time to power circuit boards, microcontroller boards, and even finished projects. However, during the checkout phase of a new circuit, wall warts present a problem. How do you measure their output when they’re plugged into a board or project box?
Do you get erratic results with your oscilloscope? As you start probing higher and higher frequencies, do the results get increasingly odder? Let's address the reasons for that strange behavior and construct an inexpensive Active Probe.
Ground faults are a curse to fire alarm systems. Even a small amount of current leaking to ground somewhere in the building can cause an unscheduled fire drill. Worse yet, a second ground fault somewhere else in the building can short out the whole system. An easy modification allows a low tech analog ohmmeter to detect insulation faults that a high tech digital ohmmeter fails to find.
The clock is made of a collection of counters. Counters made by a chain of n flip-flops result in binary ripple counters capable of dividing by 2n. A four flip-flop counter naturally counts from 0 to 15. To make it count from 0 to 9, it needs some steering logic on the flip-flop toggle inputs.
So, my wife volunteered me for “Science Day” at my son’s elementary school — an annual half day program where moms and dads taught mini-courses on everything from rocketry to zoology to chemistry. But what could I teach the kids? No sooner did the thought cross my mind, did I get the answer: build a video game!
The first project is a transformerless voltage doubler that takes a DC voltage from 12 to 30 volts and doubles it. Unlike most other voltage doubler circuits, this design can supply amps of current. The second project uses a power MOSFET in a linear (rather than switching) application.
