Tag Archives: electronics

On the Bench: LED Traffic Signal Light

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LED Stoplight

Many cities are switching to LEDs for their traffic signals, and is it any wonder? The energy savings are tremendous, never mind not having to change burnt-out bulbs all the time. Luckily for us, LED traffic signals are finally ubiquitous enough to show up at the surplus stores. Our local junk shop had a couple of big barrels of LED stoplights and turn signals of various sizes. We picked one out that still had the connector attached for screwing it into a regular light bulb socket.

LED Stoplight

 

Of course, after we made sure it worked, we promptly took it apart. It is a fabulous object, designed to be used, abused, taken apart, and maybe even fixed, though there is not much to go wrong. Click through for more gory photos and delightful design details.

 

 

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Electronics Flea Market 2008 Season Opener

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The Silicon Valley Electronics Flea Market

Saturday was the first Electronics Flea Market for 2008. We went, a little late as usual, but early for us. When we got our coffee and donuts at 8:30, there were already some vendors packing up; they had been there for hours and sold enough to call it a day. The weather was beautiful, and we all got sunburned, but we also took home a nice haul of goodies.

Above: the pretty stuff put in a cigar box for the benefit of photographers like me.

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Tiny portable AVR projects: Business card breakout boards

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XX8_complete

For all of our different AVR microcontroller based projects, we seem to find ourselves continually wiring up minimalist target boards; little circuit boards that fit both the AVR and a 6-pin header for connecting to your in-system programmer. And, when you find yourself hand-wiring the same circuit over and over again on a protoboard, that’s really just life’s way of telling you “just lay out a damn printed circuit board already.”

Coincidentally, we needed a new business card.
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Tales from the Auxiliary

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The Evil Mad Science Auxiliary is a public group on Flickr for anyone to add photos that are (at least marginally) related to posts and projects from Evil Mad Scientist Laboratories.
Lately some fantastic photos and projects have shown up in the group, so we thought that we should stop and round up a few– not all– of the great things that we’ve seen there.

The photos below were taken by their respective owners; click on the individual photos to get the full story.

DSC_2180

 

A dark detector built by cyenobite, using a tiny battery holder.

 

Joule Thief 1

 

 

 

Beautiful Joule Thief light by Jimmie Rodgers

 

 

 

Rewired 16seg POV display: Shift registers!   

Adam Greig has been having fun with AlphaPOV. (Results here.)

 

Macro shots with light ring   Bristlebot version IIBristlebot version II   Cheapest bot on Earth

Francesco (Flickr user fdecomite) made this amazing army of BristleBots, photographed with the help of his spiffy LED ring light. He even made some excellent videos of the little guys in action.

 

LED arrays   Homebrew toy blaster effects
progress

Steve Lodefink has been busy building up this set of electronics for an extra-spiffy handlheld blaster. Based on 555 and 4017 chips, it has some elements in common with our little cylon circuit. I can’t wait to see what it looks like when it’s done!

 

SP_A0133   SP_A0130SP_A0112

Channon (Flickr user plik the geek) is building up one of our interactive LED kits.

He also decorated his office printer with an overly honest label. (Coincidentally, we also did this to our own office printer.)

 

 

Finished circuits!

Speaking of interactive LED kits, A Oli Wood contributed this fabulous time exposure of his completed circuit.

So… If you’ve got pictures or projects that were in some way inspired by our projects, we would as always love to see them in the Auxiliary. And to everyone who has contributed, thanks for your cool pictures!

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Last minute Evil Mad Shopping and Projects

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Lit up segments spell out the letter M   Segments visible

Time to make some LED Micro-Readerboards as ornaments for your tree this year? Watch the short video introduction to see what they do: display a message one character at a time.

This is one of the open-source holiday electronics projects that we released last year. Our up-to-date build instruction are here, including source code. We also have an FAQ about this project, a page of technical data about it, and a discussion forum if you need help with it. The version 2.0 kits (which are still available at the Make Store) use a seriously awesome ultra-high brightness, deep red 16-segment alphanumeric display for long battery life.

As of today, you can also buy the LED displays alone– just the thing for your own custom microcontroller project, alphapov display, name tag, or ornament.

[Product Page]

Jellybean versus the mechanical mouse
Next, the Interactive LED Panel Kits (as seen in the interactive LED coffee tables that we designed with Because We Can) now come with these beautiful black printed circuit boards. Pictured above, JellyBean combats a mechanical mouse on a table made with a special-order kit that has all green LEDs.

Quite a few of these tables have now been built and there’s even a new instructable from Deadly Computer about the process of building one. During the past month we’ve slowly caught up with the huge waiting list to get a kit, so it’s much easier to get one now. We have even made up some extras of the most popular kit combinations (8 panel with all blue LEDs or blue + white LEDs), which are available in stock to buy right now, shipped to arrive before Christmas to US addresses.

[Product Page]


bugStickers

Finally, we have some new multipurpose stickers for sale. Quite possibly the best gift in the world for the software developer in your life.

“These handy stickers will increase the visual appeal of many different items. If you happen to take them to any big box electronics stores, please bring your camera and post pictures in the Evil Mad Science Auxiliary.” We’re waiting for those action shots.

[Product Page]

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A Simple and Cheap Dark-Detecting LED Circuit

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Components   Complete

Stupidly bright.

Here’s a simple problem: “How do you make an LED turn on when it gets dark?” You might call it the “nightlight problem,” but the same sort of question comes up in a lot of familiar situations– emergency lights, street lights, silly computer keyboard backlights, and the list goes on.

Solutions? Lots. The time-honored tradition is to use a circuit with a CdS photoresistor, sometimes called a photocell or LDR, for “light-dependent resistor.” (Circuit Example 1, Example 2.) Photoresistors are reliable and cost about $1 each, but are going away because they contain cadmium, a toxic heavy metal whose use is increasingly regulated. There are many other solutions as well. Look here for some op-amp based photodetector circuits with LED output, and check out some of the tricks used in well-designed solar garden lights, which include gems like using the solar cell itself as the sensor. (Our own solar circuit collection is here.)

In this article we show how to build a very simple– perhaps even the simplest– darkness-activated LED circuit. To our LED and battery we add just three components, which cost less than thirty cents altogether (and much less if you buy in bulk). You can build it in less than five minutes or less (much less with practice).

What can you do with such an inexpensive light-controlled LED circuit? Almost anything really. But, one fun application is to make LED throwies that turn themselves off in the daytime to save power. Throwies normally can last up to two weeks. Adding a light-level switch like this can significantly extend their lifetime.

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Weekend Projects with Bre Pettis: Make a Joule Thief

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Weekend Projects Podcast!
In this week’s Weekend Projects video podcast, Make Magazine’s Bre Pettis and I show you how to make a Joule Thief. The PDF file that goes with the podcast is here (450 kB PDF file).

So whatsa Joule Thief? It’s a little wisp of a circuit that allows you to drive a blue or white LED from a low voltage. Normally, if you want to light up a blue or white LED you need to provide it with 3 – 3.5 V, like from a 3 V lithium coin cell. But a 1.5 V battery like a AA cell simply will not work. But using the Joule Thief, it works like a charm. Not only does it work with a brand new battery, but it works until the battery is nearly dead– down to 0.3 V. That’s well below the point where your other toys will tell you the battery is dead, so it can steal every last joule of energy from the battery (hence the name). To learn how to make one, watch the video, which is available in a variety of formats.

The original site where we learned about the Joule thief shows you how to make a miniature version of this circuit, such that you can fit it in a tiny flashlight. However, in the video we show you how to make it big, large enough (1) to make with clumsy hands and (2) that you can see what we’re doing.

After the jump, some detailed photos of how the coil is wound in case you need more detail than in the video.

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Halloween projects and Texas

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This week the lab staff is heading off to Austin, Texas, our former stomping grounds and site of the other Maker Faire this year!

As we noted earlier, we’ll be doing a demonstration of how to build an excellent Bat Costume out of an umbrella and a hoodie. However, our primary project there will be our booth: High-Tech Pumpkins, where we will show up to a dozen (fingers crossed) halloween-themed projects, TSA willing. (Thank FSM it’s Austin, not Boston.)

While we get everything together this week, our publishing schedule will be a little wonky. However, halloween is just around the corner, so it’s time to dust off a few projects from our halloween archives!

Headless horseman   
How to hack LEDs into Lego minifigures for Halloween (Link)

 

FSM Costume - 01.jpg   
Make a Flying Spaghetti Monster Costume (Link)

 

   Croc Costume - 10.jpg
Crocodile Costume (Link)

 

Attaching long wires 2   
Easy Itty-Bitty Blinky LED Jack-O’-Lantern (Link)

 

Dalek Body-- under construction   
A Robotic Dalek Pumpkin (Link)

 

See also:

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