Author Archives: Windell

About Windell

Co-founder of Evil Mad Scientist Laboratories.

Basics: Open Collector Outputs

SN7407N

One of the joys of working with basic digital electronics– and logic gate ICs in particular –is that it almost works like building with a set of Lego blocks: One output goes here, which connects to the next input here, and so forth until it does what you wanted.

If you’ve played with chips like these, you’ve probably also come across chips with “open collector” outputs. And if not, they’re worth knowing about. Open-collector outputs form the basis of a number of clever tricks for level-shifting and interfacing between different types of logic, and from logic to other types of electronic circuits.

In what follows, we’ll work with the SN7407N, which is one of the most basic ICs with open-collector outputs. We’ll discuss what it means to have “open collector” outputs, and show some of the different ways that they are used. Continue reading →

A fantastic introduction to Maker Spaces

Jerry Isdale, founder of Maui Makers, sent in this great clip about their maker space. (The video is embedded above, and the Vimeo link is here.)

The video, from TV series Self Made in Hawaii,
is one of the best introductions that we have seen to maker spaces (and, really, hacker spaces in general)– showing people working together, having fun and building awesome stuff.

And that’s exactly what maker spaces and hacker spaces are all about: There’s fire art, 3D printers, and electronics, laser cutters, CNC machines, and even some fine footage of an Egg-Bot in motion.

More information about the video is available at the Maui Makers blog.

Basics: Power dissipation and electronic components

Lovely Resistors

An ever-present challenge in electronic circuit design is selecting suitable components that not only perform their intended task but also will survive under foreseeable operating conditions. A big part of that process is making sure that your components will stay within their safe operating limits in terms of current, voltage, and power. Of those three, the “power” portion is often the most difficult (for both newcomers and experts) because the safe operating area can depend so strongly on the particulars of the situation.

In what follows, we’ll introduce some of the basic concepts of power dissipation in electronic components, with an eye towards understanding how to select components for simple circuits with power limitations in mind. Continue reading →

Alpha Clock Five Turn Signal

From the forums:

Guy Albertelli wrote in with an unexpected use of his Alpha Clock Five kit: a turn signal machine for the back of his Xtracycle– complete with a “SORRY” button and a random-scrolling-message mode (that isn’t shown in the video). There’s even a clock mode with an improvised “second hand.”

One might argue that the scrolling messages could be a little simpler, but that’s really missing the point: this is an awfully clever application for a bright and self-contained alphanumeric LED display.

Guy’s video is embedded above. (YouTube link).

On the Future of the Internet

Project sites like ours are a product of, and are only possible in an open internet that promotes the free exchange of knowledge.

 

Legislation currently pending in the US congress–
H.R.3261 “Stop Online Piracy Act” and S.968 “PROTECT IP” — threaten, at a minimum, to significantly undermine our ability to encourage collaborative learning through linking to and direct sharing of resources and ideas. At worst, Evil Mad Scientist Laboratories could someday disappear from the web without warning, and without due process of law.

 

If you like our site, please take just a minute to contact your representatives in congress. For more information about what these bills could mean for the internet as a whole, there are more resources over at the EFF.