Some of our favorite hacks are those made with scrap materials, so we were delighted to see a contest being held by the German technology magazine c’t which focuses on using salvaged components. “Mach flott den Schrott” is the name of the competition, which loosely translates to “Make fast the scrap”.

German builder [Mario Lukas’] entry into the contest (Google Translation) is definitely unique, and certainly fits within the theme. He built a toilet paper printer that uses a bunch of recycled components to write anything he desires on a roll of the soft white stuff. His blog walks through the build details, including a bill of materials for all of the scrap bits he used to put it together. Several CD-ROM drives, printers, and even inline skates donated some components to the printer, while an Arduino controls the entire printing process.

Though [Mario] is using RSS and Twitter feeds as a data source for his toilet-side scribe, we imagine it will only be a matter of time before advertising companies seize upon this sort of technology to create personalized advertisements geared towards a decidedly captive audience.

Continue reading to see a quick video of his toilet paper printer in action.

[via Make]

[Pedro] had a busted laptop LCD screen on his hands, but rather than throw it out, he brainstormed what he could possibly do with what would typically be considered a worthless item. He decided to make a simple art installation using the scrapped part, so he gathered a few other supplies and got to work.

The first thing he did was pull the LCD screen from the laptop, separating the front panel from the backlight panel. He drained the liquid crystal fluid from the display, and set it inside a picture frame in place of the glass. He added spacers around the edge of the frame so that the backlight could be mounted several inches behind the LCD panel.

[Pedro] then found a few polystyrene and polycarbonate plastic items from around the house, and placed them inside the frame. As you can see in the picture above, the polarizing filter built into the LCD screen makes for some pretty cool effects.

While you could debate for hours over exactly what is art, there’s no denying that his PolFrame looks cool and is a great way to save electronics from the scrap heap. We just want to know what he did with the LC fluid he drained from the screen!

Take a moment to think about how many old or damaged computer motherboards you have tossed away over the years. Sure we try to repurpose everything we can, but reclaiming electronic components from complex devices can be overly time consuming if you don’t have the proper means of doing so.

Ideally, if we were to try removing components from a motherboard, an old stove or an unused toaster oven would be great. If you didn’t have either item at your disposal, you could always attack the board with a soldering iron and some braid – but who has the time for that?

[Giorgos Lazaridis] over at PCBHeaven put together a quick video demonstrating his favorite technique for salvaging components after a motherboard has outlived its usefulness. Using a 2000W heat gun, a few hand tools, and couple of metal pans, he had the entire board stripped bare in about 30 minutes time. He talks about some of the best parts he has discovered while salvaging and points out a few hard-to-find items that can be easily obtained by tearing down a motherboard.

Sure his process might not be as easy as inverting a PCB in an oven, but his method is cheap, portable, and takes up very little space.

Keep reading to see [Giorgos'] video demonstration and don’t forget to check out some of the other cool stuff he has done in the past, such as his temperature-controlled soldering station, this acrylic bender, or this bench top function generator.

Think Geek has a growing pile of returns and damaged product that they’re trying to get rid of. The purveyors of technological oddities, like any other large retailer, sometimes have stuff that doesn’t work right, or has been damaged somewhere between factory and consumer. The broken bits find their way back to the distribution center and now they’re stuck with the task of doing something with it.

They can’t sell it, and we’re happy to say they don’t want to throw it out. So they’re considering giving it away to worth-while causes like Hackerspaces and schools. Looks like no real details have been hammered out as of yet. But if you belong to a Hackerspace or other group that can find a use for this stuff, click-through the link above and sign up to let them know you’re interested. The goldmine of reusable stuff is located in Columbus, Ohio and pick-ups might be available. Otherwise they’re going to need to find a way to cover the cost to ship boxes to those interested.

Don’t forget to document your projects and let us know what you use this stuff for.

[Thanks RenderMan]

An accurate drill press is an essential tool for making your own through-hole printed circuit boards at home. Reader [Josh Ashby] offers up a solid design using scrap bin materials.

A major issue with PCB drilling is that even the slightest horizontal play will snap the delicate carbide drill bit. Hobbyist-grade tools such as Dremel’s drill press attachment are usually too sloppy for this task, while a more precise instrument might set you back a couple hundred bucks.

[Josh’s] design uses a nylon “sled” moving vertically in an aluminum u-channel track. Most of these materials were salvaged or were acquired inexpensively from a local hardware store, and assembled in less than a day. Surprisingly, this low-tech approach has proven sufficiently smooth that he’s yet to break a bit while drilling. And the entire setup, including the knockoff Harbor Freight rotary tool, cost less than the wobbly name-brand accessory alone.

We’re sometimes shocked at the electronics included in ‘disposable’ items. For some reason (our tech inclinations?) we’ve been getting those audio greeting cards from relatives and it kind of kills us to see the PCB, batteries, and speaker in what would have otherwise been a fully recyclable card. Now we’ve got several sets of those guts waiting around for our next project.

[David Cook] cracked open another disposable item, an Avatar action figure that came as a Happy Meal prize. What he found inside will actually be useful. There’s a battery holder for the three coin-cell batteries, A blue LED (for those blue LED hacks our commenters are so fond of), and a piezo speaker. There are some other discrete components that may be of use to you but the first three are certainly a boon for those that are  junk scavengers like us.

Has anyone else found some goodies inside these types of free toys? We’d love to hear about them in the comments. But for now we’re just glad to see the first good thing to come out of that annoying market saturation that accompanied the movie release.

Incidentally, [David's] h-bridge writeup is our go-to reference for building quick motor controllers from parts on hand, or that can be purchased locally.

[Thanks Gron]

Old computer mice are being abandoned in droves. They’re tossed out because of dirt, obsolescence, or for being entirely too beige. Anyone who has a computer usually has more than one mouse and you can get them for pennies, if not free just for asking. Fortunately for the discriminating (read: cheap) hacker, these little widgets are chock-full of project parts. Today’s How-To will dissect a computer mouse, extract the useful parts, and give some ideas about how to use them.

Here we have a standard PS2 mouse; a USB mouse will look pretty much the same. We’ll talk about optical mice later on.

Lets open it up. First, take out the mouse ball. Then there will be one or more screws on the bottom side that need to come out. Screws are sometimes hidden under the rubber pads.

The first thing to notice is the cable connector. Most mice have a very convenient plug for the cable, instead of soldering it onto the board. That’s the first usable part: a 4 (or 6) conductor cable with a nice plug on one end. The socket can be removed from the PCB and used in other projects.

With the cord out of the way, we can start pulling out parts. First thing that pops off is the mouse wheel. Yes, it’s just a big rubber wheel. If you’re annoyed by the mouse wheel’s clicking noise, you can silence it. There are at least two micro-switches and usually a third one under the mouse wheel which can be used for bump sensors or buttons.

Next thing to take out are the two plastic slotted discs. They’re the encoder wheels. They turn whenever the mouse moves and interrupt an IR beam, producing pulses. It used to be that precision encoder wheels were pretty expensive, but not anymore. Every single (non-optical) mouse comes with a pair built in.

On either side of the encoder wheel are some little boxes. One side is an IR emitter, and the other side is a pair of IR detectors. Sometimes the emitters and detectors will be one complete unit. A pair of detectors is used because with 2 detectors slightly offset, it generates quadrature encoding, so that mouse knows the direction of rotation.

These IR emitters and detectors are fairly modular pieces when it comes to hacking and can be removed with some careful desoldering. It is a good idea to use a multimeter to see what kind of voltage is going to them before removing them. They are probably TTL parts, because mice are powered by 5v, but sometimes they are an even lower voltage. The emitter/detector pair by itself can be interfaced directly. Those parts alone can be used for a proximity sensor or for a line following robot.

Add an encoder wheel and this sensor setup has lots of uses. From a tachometer, to a wind speed indicator, to sensing a robot’s speed, this will do it. The quadrature output (with some decoding) can be used to measure distance, direction, and speed.

One tricky thing about using the encoder with the IR sensor is getting the emitter to line up with the detector(s). No problem: instead of desoldering the parts from the PCB, use a rotary tool to cut off the little piece of PCB that has the sensors on it (already lined up). Wires can then be soldered to the pins/traces on the other side. If holding the encoder wheel in place is a problem, a hunk of the mouse casing can be used with it. Be sure to leave enough PCB to keep it stable on the mouse casing.

This is a picture of an encoder wheel with quadrature from a PS2 mouse on a small robot. Rather than make custom parts, the mouse is carved up and the whole assembly is fitted to the motor axis.

What’s left to salvage on the mouse? The sensors for the mouse wheel. Depending on the model, the mouse wheel movement may be sensed with switches or a low resolution encoder, suitable for measuring slow rotation.

The final bit is the mouse controller chip. At first thought it seems pretty useless: it’s a single purpose part made specifically to run a computer mouse and nothing else. However, if your controller chip isn’t an anonymous blob, the datasheet could be very enlightening. Octopart can help find datasheets based on the chip’s part number. This (PDF) is a typical datasheet for a mouse controller.

This specific part does a number of useful things:

• decodes the quadrature input from the encoders
• keeps a running count of the number of encoder pulses in a set of registers
• filters out jitter
• debounces the micro-switches and keeps track of their state
• packetizes the information and sends it up the cord.

For a PS2 mouse, getting at these features is not too difficult. The PS2 protocol is pretty friendly, even for microcontrollers. Here’s an example of interfacing a microcontroller with a mouse. For USB mice, check the controller’s datasheet to see if it can do both PS2 and USB; with older mice there’s a decent chance it does. While pure USB is not very easy to talk to with a microcontroller, it’s really easy to hook to a PC (with the right software).

We promised a look at optical mice. Optical mice do not have any rotary encoders. There are still some switches and a low-res encoder for the mouse wheel. What an optical mouse has in it is a mini-camera, lights, and lenses. The light is probably a fairly standard LED, although they tend to be bright, and the lenses are purpose built. However, it is possible to interface directly to the mini-camera or use it as a really poor scanner.

We hope this How-To has sparked some ideas and that your obsolete mouse won’t seem as useless anymore.

If you want to keep your money, I’d avoid RadioShack as much as possible. When you’re stuck because you can’t find a freaking 10kohm resistor, it’s fine, but the markup on their low quality parts is insane-their clearance prices aren’t too bad. As much as people bag on RadioShack, just remember that nobody else bothers to sell electronic parts in the middle of nowhere.

Shipping can eat your project budget quicker than anything else. It’s the reason that I’m sometimes willing to pay $1 for $.05 in resistors at RadioShack. When I’m buying parts, I try to buy from a single supplier if possible to maximize my parts budget.

Stocking up on parts in bulk can help make projects extra affordable later on. Buying a quantity of resistors, capacitors, PNP and NPN transistors and a decent supply of linear voltage regulators will save you a fair amount of money later on. I love it when I can build a $30 project for the cost of a proto-board and an odd capacitor.

Just about every electronics component manufacturer will provide free samples on request. That’s right – free. It’s usually just a matter of creating an account on the manufacturers web site and selecting the components you need. As a rule, I don’t mention when I’ve sampled parts for a project. Seriously, they’ll get a little suspicious if 100 people suddenly sample the exact same parts. Samples aren’t limited to semiconductor companies. [ladyada] has a nice list of sample providers, including enclosures and connectors.

Digi-Key carries just about every part you can think of. These guys prefer to sell large quantities, but they’re happy to take small orders. Orders are shipped out fast, but they’ll tack on an extra $5 fee if your order is under $25. Even if you’re not ordering, they usually have data sheets linked for every part they carry online. If you’re wiling to jump through the hoops, you can even create a parts order that’s linkable from your website – it can make it much easier to share a project with others, but I usually find that a few part numbers get deprecated as time goes by. Oh, and they’ll send you a massive parts catalog that’s handy for parts hunting and brain storming.

Mouser Electronics is one of my favorite suppliers these days. They have reasonable shipping options and are fast with UPS ground orders showing up at my house within two days. Their inventory isn’t always the best, but substitution parts are usually easy to find because the online catalog links to web enabled PDF pages from their print catalog. It makes cross-referencing very easy. Like Digi-Key, they’ll send you a massive parts catalog to shove under your monitor.

Futurlec is a great place to get incredibly cheap parts, but you won’t be seeing your order for about a month (ok, so my last order showed up after three weeks). I suggest stocking up on connector headers and resistors. I haven’t had to make a late night resistor run in a couple of years thanks to these guys.

Sparkfun electronics is like a candy shop for Hack-A-Day readers. They carry higher end parts like GPS units, GMRS modules and micro controller programmers. Pricing varies a bit, but I can always find something interesting there. If you prefer professionally made PC Boards, they even put together an inexpensive PC Board service.

ebay is one of my favorite places to shop for parts. It’s a great place to buy brand new $150 stepper motors for $20 or hunt down funky, hackable hardware. People certainly try to sell single components, but it’s usually not worth the effort.

Salvaging parts is the absolute cheapest method for parts shopping. Thanks to custom ICs and SMD parts, newer electronics don’t normally have much in the way of salvage value. On the other hand, older hardware is a great source for parts. My current favorite salvage source is the dot matrix printer. They’re easy to take apart, have nice power supplies, and they’re loaded with quality heat sinks, wiring, connectors, hardened steel rods, and stepper motors. The bigger the dot matrix printer, the bigger the stepper motor. If you can score a few of the same model, you’ll end up with a few matched sets. People hate throwing them away, so they’re easy to get for free.

Lack of availability can be a problem, but obsolete parts are another way to keep costs down. Originally, the UCN5804B stepper driver I used for the cutting board CNC machine cost about $16 each. Now that they’re deprecated, they can be had for about $5 each.

Grab bags are another good way to save money. They’re usually full of loose parts that’ll have to be identified, but they’re cheap. The guys over at uchobby put together a nice how-to on sorting them.

Thanks to the movement from mail order to internet suppliers, the parts company scene is huge. There are loads of production part and surplus companies around. Here’s a quick list of shops that’ll probably be useful if you’re looking for parts.

Digi-Key electronics
Mouser electronics
Futurlec
Sparkfun electronics
eBay
All Electronics
BG Micro
American Science & Surplus
Goldmine Electronics
MPJA Online
MCM Electronics
Parts Express

Got a favorite shop? Drop the link in the comments and I’ll add it to the list.