Starting next Monday we be adding some themed posts into the mix. Every couple of weeks we will pick a new theme. Our first theme will be about hacks and projects involving high voltage.   Each day we will have a new post based on the current theme. To make this happen though, we need your help.  If you have been working on something that involves high voltage or you know someone who has, hit us up on the tip line.  If you have a cool high-voltage project but haven’t posted it online yet, take a look at this link where we show you some options.

Several people have been asking a similar question to,

“How do you at Hackaday keep track of and organize all your equipment?”
-[Jeff Allen] and others.

We have a variety of resources to help you keep track of your tools, equipment, parts, and supplies! Follow us after the jump for some tips for keeping your workspace clean and tidy.

First and foremost, we admit, we’re not the cleanest of bunches. We work on several projects at a time, receive ungodly amounts of mail and paperwork, struggle with dust and other allergens, all while writing wonderful articles. So please forgive us if our workspace is just a little messy.

So what can I use to help keep my parts orderly?

[Andrew Lybarger] asked us if Spice Containers would work, and was worried if the magnets would interfere with electronics. In short, we think they would work perfectly. Resistors, LEDs, etc should all be fine. We wouldn’t put our expensive ICs in there though, just to be safe.

For those that don’t want magnets, we suggest clear dividable containers. Or, my personally favorite for on-the-go hackers. A tackle box, its many holding areas for hooks and other things work great for transistors and caps. The bottom part of the boxes is usually quite roomy to fit a soldering iron (or two).

HAD writer [Devlin] prefers to keep all purchased components in the rail/tube/bag they come in, stick a label on and they’re good to go. Writer  [Mike] goes a step further by keeping the purchase order and a spreadsheet on his PC with a list of parts and supplies, all it takes is a GREP search to find the right IC.

I just have too many tools, help me HAD!

If you have one or two items that can fit in the above mentioned tackle box, you’re set. But some here might have everything from a sledge-hammer to a pair of tweezers. There is no real easy way to say this, but buy a tool chest, or better yet make one.

How do I keep my workspace clean?

First and foremost, prevention. When you’re done with a project, put your tools away! We would like to slide in a little note here to mention not only a clean work environment, but a safe one.

For a computer workspace, nothing is worse than horrible amounts of cables creating a rat’s nest. Zip ties and a little ingenuity can go a long way.

What about the ungodly amount of paper work?

Whether digital or real, find a filing system. I know several HAD writers rely on Google products. And with Gmail, Calender, Documents, and more all interlinked, I’ve never lost an important file.

Outside of the digital side though, accordion files are great! We have several around the office for articles, finances, and more. For a lot of mail, slot divided organizers work wonders (And we always know where a pen is!)

Final note:

Don’t let your desk and work area get overfilled with tools and supplies in the first place. If you clean up after you’re done every time, you’ll know where everything is and will spend less time looking and more time hacking.

Here is where the fun begins.

We get to now ask the fun questions; how do you, our readers, keep organized with your equipment, tools, parts, supplies and other necessities of hacker-dom?

Want to ask us a question instead?
Send your questions to askHAD@hackaday.com for consideration. They will be chosen based on a complicated system of random number variation involving furry woodland creatures and how we feel at the moment that we read them. Do not get offended if you question does not get published. We get tons of questions already and we don’t intend to publish them all.

Christmas has come early for us. This is our 3,000th post since launching Fall of 2004 doing just one post a day. The outstanding stat though is the 50,000 comments in the system. The team at Hack a Day would like to thank you, the readers, for bringing in all of our best tips and being part of this great community.

This is a paid, freelancing position that requires professionalism, consistency, and reliability. We want to hear from people that are passionate about software/hardware hacking and growing Hack a Day. To apply, send the following to jobs@hackaday.com

• A short bio about yourself
• 3 example daily posts written in the style of Hack a Day
• 3 software or hardware how-tos you’d like to see. For examples of work we’ve done in the past, look here, here, here, and here.
• A couple sentences on how you would improve the site either through features or content
• Any additional reasons why you would make a good fit for Hack a Day

Do not send any attachments. Having your own blog you can show off is a definite plus.

[photo:fbz]

Congratulations to [John Keppel] for his winning t-shirt design. He wins a Dash Express, an in-car navigation device with both cellular and WiFi data support. It’s running Linux on top of the Openmoko FreeRunner’s hardware platform; yes, [John], we do expect you to hack it. We’ll let all of you know when we plan on putting the shirt into production. Thank you to everyone that entered!

The final day for entries in our Hack a Day T-Shirt Design Contest is today. Get your entries in by midnight Pacific time and you could win a Dash Express (or non-US prize).

We had a lot of entries for our Fail contest; there can only be one winner though. We liked [Gordon LaPlante]‘s entry pictured above most of all. It’s big, it’s broken, and it’s black and white; that certainly sounds like us. [Gordon] wins $100 worth of No Starch Press merchandise.

There were plenty of other honorable entries. You can view them in the Hack a Day Flickr photo pool. We saw a couple themes emerge during the contest and have highlighted some of them after the break.

Hamsters

This caught us off guard. Our downtime message said, “we’re adding more hamsters to our server power plant” and people just ran away with it.

[hohan]

This one by [jetblackscreems] looks like it has lots of mascot potential, spelling be damned.

Fail Whales

These were natural given our Twitter inspiration.

[oneamericankid]

[Bjonnh]

[reenigneesrever]

[macetech] made probably the most Hack a Day appropriate rendition of the Twitter image.

Error screens

[jonathanrice78]

[AdamsGrizzly]

[dibbqwaz] made a fine ASCII 503 that should probably be in the previous category.

[adamsih300u]

Angry robots

We’re sad this didn’t gain more traction.

[enrique jimenez]

[einsofayin]

This was a really fun contest to hold and we’ll be having many more in the future. Check out our Hack a Day T-Shirt design contest, which ends this weekend.

[by John]

[by evolve]

I think [Joel]‘s entry was in case we were handing out the prize at random.

Keep those entries coming and let your friends know about the contest too!

We’ll begin by building the solder fume hood. Yes, we said “hood”, not just “extractor”. While there have been some nice fume extractors hacked together, this system integrates all of your soldering tools into and around the fume hood.

The purpose of a fume hood is to draw solder fumes away from the person soldering. Besides the health risks, these fumes are really annoying as they follow that pesky law of the universe: “No matter where you happen to be sitting, solder fumes will float directly towards your face.”

To start, let’s gather materials:

Once all the materials are gathered, we can begin cutting the plastic of the Rubbermaid container. To cut this material, use a plastic scoring tool. When you make your cuts, make sure to repeatedly score the line you want to cut until the blade goes all the way through the plastic. Do not try to score it and snap it like acrylic. This material has a bad tendency to crack in places you didn’t intend. If your plastic cracks, all is not lost. Since the plastic is soft, you can weld the cracks back together by touching it with the tip of a high temperature hot glue gun.

First, we need to cut a hole for the fan in the top of the hood. Take off the cover of the fan and use it to make a hole slightly smaller than the inside diameter of the fan cover in the top center of the hood. The fan is actually going to hang from the top of the hood and pull the fumes out of the hood when turned on.

Once the big hole is made, drill smaller holes for the screws used to hold the fan together. With the nuts on the outside, screw the fan assembly to the top of the hood.

To reattach the top cover of the fan, use some scrap solid core wire or twist-ties to connect the spars on the top cover to the spars on the bottom fan assembly. We used only three twist ties as this is plenty to keep the fan cover in place.

Now we are ready to mount the light. Mark a good place to attach the light in the back top of the hood. It is likely that the mounting screws that came with the lamp are too long. Additionally, the lamp might get too hot. To prevent the lamp from melting the plastic, we cut about five half-inch spacers out of some of the plastic cut off earlier. To make life easier, pre-drill holes in the center of each of the spacers. Use a couple of the spacers on the inside to lower the lamp away from the top of the hood, and then use a few on the outside to cover the sharp points of the protruding screws. Alternatively, encapsulating the screw points on the outside of the hood with hot glue works just as well.

Next, cut the main window of the fume hood. Ours goes all the way across the front and is about 7 inches high. It’s a good idea to start with a smaller hole and expand it to see what feel comfortable for you to use. Make sure it is easy to reach the top back wall of the hood. This is where the controls will go later.

At this point, you can use zip ties to attach the active carbon filter to the top of the fan.

Plug the fan and the light into a powerstrip. Make sure the fan and the light are turned on so you can turn the entire hood on and off from the strip. Plug in the soldering iron and you are ready to go. The adjustable base of the fan is used here to hold the excess wire from the soldering iron; keeping it out of the way.

A slightly more advanced option for the front is to cut another smaller window (about 6.5 by 13.5 inches) just above the first one and add a piece of acrylic. This greatly improves visibility. Make sure to cut the acrylic about a half inch larger than the window to give yourself a surface to glue. Attach the acrylic on the inside of the fume hood with hot glue.

To improve your soldering iron set-up, you can get a professional soldering station. But why spend $50 on a temperature controlled soldering station when you can build your own for cheaper! Afrotechmods has a rough guide to building a great adjustable temperature soldering station.

To install this soldering station into the fume hood, simply cut a hole in the back of the hood large enough to stuff the dimmer and the socket through it from the front side and small enough to make sure the mounting holes still have some plastic to mount to. The box will be attached to the back of the hood, but the faceplate needs to be on the inside.

You’ll notice that there is a different knob on the dimmer switch. We used a scrap knob with a flat bottom (comes complete with cool numbers) on the dimmer switch instead of the stock knob.

Regardless of what soldering station you use, if it doesn’t have auto turn off (which is good for fire prevention), put a grounded AC appliance timer inline with the iron. These timers allow you to automatically turn on or off any AC appliance at any time you want within a 24 hour period, but don’t rely on it to keep your iron turned off, as it will turn it back one every 24 hours. It’s better than nothing and is a cheap option, as they run between 5 and 10 bucks at local hardware and super stores. The one we use has increments of about 15 minutes. Setting it for 30-45 minutes works well.

For some reason, the designers of these timers want to take up all the plug space they can by placing the plug practically in the center on the back of the timer. Luckily, the scrap dimmer knob we found has a low profile, and allows the timer to plug in with little interference to the dimmer. A better option is to get an aquarium timer. These are designed with a better form factor and generally only cover one socket.

Many cheap soldering irons come with a sponge to clean the tip. If you think about it, it’s not really the best idea to use a sponge to clean your soldering iron; it works, but it also cools down the tip of the iron every time you clean it. If you are doing delicate work and clean your tip once every couple of soldering points, this can lead to cold solder joints and bad connections.

Professionals use a flux covered wire mesh to clean the tip. This method draws off the solder and uses flux to clean the tip. Every now and then, you just kind of stab the mesh with your iron a couple of times to clean it off. The problem is that this method costs around $10.

Instead of buying some job specific wire mesh, just use a copper coated scourer to clean your soldering iron tip. Usually used for cleaning pots and pans, these little guys can be picked up at your local grocery store for $1 or so a pack. The copper mesh isn’t coated with flux, but the copper itself will draw the excess solder from the tip of the iron. Do not get the steel scourers, as they are only good for cleaning dishes.

A great addition to our ti
p cleaner is the use of a simple $1 “locker organizer” picked up from the dollar aisle of the local super store. Just shove the scourer into the organizer to keep it from sticking to the iron. The magnet on the bottom will also weigh it down enough to keep it on the table when you make spastic stabs at the scourer in frenzied hacking sessions.

Surface mount soldering is becoming more common amongstl hackers and hobbyists. This work is notorious for being one of the most tedious and annoying practices known to man. Of course, having the right tools for the job helps. The cheapest surface mount rework stations cost upwards of $100. In the past, our own [Will O'Brien] showed how to make your own surface mount reflow iron.

A reflow iron or pen isn’t the only tool you need for surface mount soldering. Sometimes you’ll need a hot plate or oven.

For smaller jobs we’ve found that using a candle warmer can be useful. We got ours for $5 from a super store. The plate might not get completely hot enough to melt the solder by itself, but it does help a lot when you use a soldering iron or a reflow iron by decreasing the time and effort it takes to warm the joints. The sweet spot on these warmers is usually directly in the middle of the black steel plate.

Simply place a PCB in the center of the candle warmer and allow it to raise the temp of the solder joints. Use a reflow pen or soldering iron to heat the particular joint you want the rest of the way. It will take a lot less time to melt the solder this way. This is especially useful when placing surface mount parts, but can also be useful when taking them off of a PCB.

Placing all of these components together inside the fume hood, the Hacker’s Soldering Station is complete. With this project we set out to make a simple, cheap solder fume hood complete with a time and temperature soldering station. We ended up with a great soldering station and fume extractor set up. In fact, this has now replaced one of the WLC100 soldering stations we usually use.

This is a paid, freelancing position that requires professionalism, consistency, and reliability. We want to hear from people that are passionate about software/hardware hacking and growing Hack a Day. To apply, send the following to jobs@hackaday.com

• A short bio about yourself
• 3 example daily posts written in the style of Hack a Day
• 3 software or hardware how-tos you’d like to see. For examples of work we’ve done in the past, look here, here, here, and here.
• A couple sentences on how you would improve the site either through features or content
• Any additional reasons why you would make a good fit for Hack a Day

Do not send any attachments. Having your own blog you can show off is a definite plus.

[photo:fbz]

Pictured above we see one of the amazing cable braiding machines from UK based Cobra Machinery. This link was found on a post about creating your own high end speaker wires from cat5 cable. At the time we hoped to find a DIY braiding machine. No such luck today but we did come across and interesting site in the process. diyAudoProjects has a ton of great how to guides for all things audio. They even have a few walkthroughs for creating your own speaker wires.

We looked at the robotic dexterous hand from The Shadow Robot Company. Browsing through their high rez image gallery its pretty clear to see the product has been progressing nicely: 24 degrees of freedom complete with force feedback and a GPL based software package.

Three years ago we covered the Nokia 770 internet appliance and it’s upcoming SDK. The device has now been replaced by the Nokia N810 (pictured on the right). However, open source support from Nokia has continued to develop. We found a blog from software developer Ari Jaaksi where he talks about Nokia’s involvement in the community. Recently he discussed the latest news from MAEMO, the platform used for open source development of Nokia internet tablets and other Linux-based devices.

This hack shows how to make a dumb terminal out of a keyboard, LCD screen, and an 8-bit microcontroller. From time to time, a portable dumb terminal can be handy for when you have to rescue a headless server that’s acting up or if you are building a minicomputer out of a WRT, or if you just want to learn how to run a keyboard and LCD screen with a microcontroller. This super simple serial terminal will use RS-232 to control a headless linux system. Additionally, you might want to check into some of the command line interface programs that allow web browsing, AIM and IRC chatting and more directly from the terminal, but nothing beats being able to track your pizzas with this device.

The Linux system in question here will be Linux Mint. It’s a young distro based on Ubuntu that’s gaining a lot of attention lately, though the principles can be used for other Linux distros.

The Hardware:
For this How-To we’ll be using an ATMEGA128 running at 16MHz. Since this device will be communicating through RS-232, we’re going to need a level shifter. RS-232 uses 12 volt signals which will fry our 5V microcontroller. To fix this problem, we’re going to use a MAX233 chip.

This is the schematic of the level shifter circuit.

This is an example layout.

I’m using the ET-AVR stamp module with the stamp board for this project. This dev board is cheap and has the essentials built in. I’ll be using the on board power supply and the MAX232 RS-232 level converter.

The LCD chosen for this project is a very common 4×20 character LCD. These LCDs are really easy to control with a microcontroller(PDF), and even without one(PDF). The HD44780 chip allows for several bit widths for parallel programming, as well as commands, and even custom characters. This LCD has nice software library, which makes it even easier to use.

A more attractive choice would have been to go with a graphical LCD, which are also supported by our library, however, we only had the character LCD on hand.

A common AT keyboard will be used for character input, again these aren’t hard to find, you probably have an extra one laying around somewhere .

If you don’t want to buy the ET-AVR, you can build the circuit for this hack yourself. (Click for larger pic).

A full parts list of above circuit: :

If you would like to use the ET-AVR or some other dev board, you can use this parts list:

The Software:
We used WinAVR with AVRlib installed. AVRlib is a set of libraries that can run servos, set up A/D conversions, etc. It can do pretty much anything else you need it to do. To install WinAVR, get the newest version here and follow the directions on the installer. We generally don’t follow the directions here for installing AVRlib and place it into the include folder of WinAVR installation found at C:/WinAVR/avr/include/AVRlib. This way your included headers are easier to see and find.

eg. #include <AVRlib/servo.h>

Once this is done, you can open up Programmer’s Notepad and begin coding. We’ve already written the code for this project (with room left over for some adventurous readers to modify).

The Keyboard Protocol:
Keyboards use a simple serial communication setup. There are only 2 lines, the DATA and the CLOCK. Generally, nothing is happening on these lines (both the CLOCK and DATA lines are high) until you hit a key. Once a key is pressed, the DATA line goes low. Shortly thereafter, the CLOCK falls. The clock will go for a total of 11 cycles. As this happens, data must be read form the DATA line on the falling edge of the clock. The data is sent from the keyboard in reverse (least significant bit first) with a parity and a stop bit.

The overall data package is:

The Start bit, Parity bit, and Stop bits are going to be ignored in this simple hack.

After the keyboard sends a key’s scancode, it also sends a 0xF0 when the key has been released.

Looking at an example, it is easier to understand. Imagine the ‘m’ key has been hit on the keyboard. The data line goes low to make a start bit, then the scancode is sent with the LSB first, then the parity (odd parity) and a stop bit. Since the scancode for ‘m’ is 0x3A, we should get that value in the data portion of the package. Again, the keyboard sends data LSB first, so since we are expecting 0x3A (binary 00111010) we will actually get the reverse of that (binary 010111100). Just remember to read the data bits from right to left to make it easier to see the scancode. After the data, we’ll receive a 1 in the parity bit to make the package odd parity, then the stop bit. After the scan code has been sent, the keyboard will send another scancode when the button has been released. This release code is always 0xF0 and can be ignored, and it gets handled in the code.

So when ‘m’ is hit, the keyboard sends :

A more advanced explanation on how this works can be found elsewhere.

We must only read the data line as the clock falls to make sure we get good data. We attempted to do this using an external interrupt on the ATMEGA128 and AVRlib’s external interrupts routines. This proved more complicated than it needed to be. We then remembered that not too long ago Sparkfun had posted about some kind of keyboard widget on their site that used an AVR. The code for their keyboard reading routine was really simple and didn’t use external interrupts at all. We modified the “getkey” routine from the one [Nathan] at Sparkfun wrote for their key-counter widget.

Once the scancodes have been read, they must be converted into something useful. As far as we could tell, keyboard scancodes have no mathematical relation to ASCII code so we set up two ASCII lists. Each list is actually an array of ASCII characters. One list has all the values for shifted characters, and another list has the values for unshifted characters. We looked up the ASCII value for each scancode and placed them in the array in order. This allows for a simple way to return the ASCII value of a given scancode.

When you hit the ‘h’ key for instance, the program catches the scancode 0×33 and goes to the 0×33 rd value in that array, which happens to be 0×68, the ASCII value of ‘h’. The resulting ASCII character is sent to the LCD and to the UART, both being controlled by AVRlib to make them easier to deal with.

There are a lot of 0s used as placeholders in the arrays. This is because AVRlib automatically loads the LCD’s CG RAM address 0×00 (the ASCII code for NULL) with a character. Basically, if those codes are send to the LCD, it will just look like garbled mess. We used ’0′ so we could tell what was going in if that were the case.

Extended keys are not currently supported. The Function keys (F1-F12) have been given normal functions used in Linux, but not supported by the rest of the program. For example, pressing F1 sends the same command as “Ctrl+X” in Linux. See the code for the other function keys. Not all the keys are used (purposely) so if you want to add custom functions to the terminal, there’s plenty of space to.

The UART:
The ATMEGA128 has two UART ports. Using the first one (UART0) characters can be sent from the AVR to the terminal, and vice versa. The UART is initialized and set to 9600 baud, 8-bits, no parity, one stop bit. Make sure to set the terminal program to the same settings. We’ll modify Linux later to make sure the settings match.

With AVRlib, using the UART is a breeze. Simply initialize it, give it a baud rate, and you can start sending and receiving data.

Fiddling with Linux:
You’ll either need a monitor and keyboard on the Linux machine, or SSH into the machine and set this up.

There are several good guides on the internet for setting up a Linux machine to use a serial console. However, Linux Mint is based off of Ubuntu, which is a bit different than most OSs when it comes to setting up serial access at boot. This guide explains the basics, but we’ll need to tweak that a little to make it work for us.

First you need to find out if you even have a serial port on your machine. Look at the back and try to find a DB9 connector.

Now you will need to figure out what that serial port is referenced on your machine. Open a terminal window on the machine and enter the following command:

======================================
$ dmesg | grep tty
======================================

The output will be something like this:
======================================
[ 35.742036] serial8250: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
[ 35.742435] 00:08: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
======================================
This shows that we have 1 serial port on this particular machine. And it is called “ttyS0″.

Now we must set up a way of logging into the serial console. This is handled by the getty process. This process will open the tty port you specify and send a login prompt.

To set this up, we need to create a file in /etc/event.d called ttyS0. Open up your favorite text editor and type in the following:

======================================
start on runlevel 2
start on runlevel 3
start on runlevel 4
start on runlevel 5

stop on runlevel 0
stop on runlevel 1
stop on runlevel 6

respawn
exec /sbin/getty -L 115200 ttyS0 vt102
======================================

Now save this file as /etc/event.d/ttyS0.

Now, that’s fine for the regular users on the machine, but to do things as root, there will have to be a pass in the /etc/securetty file. Go to /etc and use a text editor to open the securetty file. (That’s “securetty”, not “security” ).In this file, type “ttyS0″. This allows that port to have root access. Save the file and close the editor.
Now the final step is to have the console available when the machine boots. To do this, we must modify the grub bootloader. You have to go to /boot/grub and edit the menu.lst file. First go there and make a clean copy of the menu.lst file:

======================================
cp /boot/grub/menu.lst /boot/grub/menu_orig.lst
======================================

Now open menu.lst in a text editor and type the following

======================================
serial --unit=0 --speed=9600 --word=8 --parity=no --stop=1
terminal --timeout=10 serial console
======================================

This first line tells grub that you want ttyS0 to be used (–unit=0) with a baud rate of 9600 (–speed=9600) using 8n1 (–word =8–parity=no –stop=1)

The second line says to display the terminal on both the serial console as well as the screen, if there is one.

If you want to watch the boot messages on the serial console, you can add the following line to the end of the “kernel” line in this file:

======================================
console=ttyS0,9600n8 console=tty0
======================================

Save this file.

Now you should have access to the serial console when you boot, but the default shell is bash. This is bad because bash sends a lot of extra characters when it executes commands. On many terminals, these characters are stripped from displaying, however, it is hard to do that on an LCD, and with only 80 characters, we don’t have much room to spare on our screen. We need to use something a little simpler.

[Fabienne] suggested using sh as the shell to get rid of bash’s weird characters. This worked during tests, so we made it the default shell on the machine. This allows it to automatically load during the boot, making it much easier to use with the device we’ve just made.To do this, simply open a terminal window and type:

======================================
chsh
======================================

This will ask you for your password. Once you enter it, you will see a screen like this:

======================================
Changing the login shell for <username>
Enter the new value, or press ENTER for the default.
Login shell [/bin/bash]
======================================

At this point you need to type the following:

======================================
/bin/sh
======================================

Hitting ENTER again will save this new setting.

Now you are ready to connect the device and see it in action!

Connecting the device:
You can play with this on a windows machine, but its real power is with a Linux machine. If you have a Windows machine, you can now communicate to the device through hyperterminal or some other terminal program. Just plug in a serial cable to the DB9 plug and set the terminal to 8n1 as mentioned above. Typing on the keyboard will display on the terminal and on the LCD.

To use it with the Linux machine, plug in the DB9 to the serial port on the computer, and turn the machine on. The first that that should happen is that the system will ask you to “Press any key to continue”. Hit anything on the keyboard to begin loading the OS. After pressing the key, you should see all the boot information scrolling on the screen. Once this stops, hit “enter”. This will bring up the logon screen (remember setting up the getty?).

Type your login name, and hit enter, then your password. As with most Linux systems, typing in the password field will NOT print to the screen. Go ahead and get an “ls” of your home directory. Notice that the screen isn’t large enough to show all the files and folders. We’ve written in a simple single screen buffer that will show the previous 4 lines displayed on the screen. So this kind of emulates a “Page Up” function.

Now you have the code, and the hardware lists, lets see what you can do with it.

We covered many of [Jason Rollette]‘s personal projects in the past and are happy to welcome him as our newest Hack-A-Day contributor.

The electronics industry has shifted to lead free compliance, but most hobbyists haven’t even considered the personal impact of using lead. Today’s How-To will cover what it takes to switch from tin/lead solder to completely lead free. Our previous posts Introduction to soldering and the follow-up still apply to lead free. You may have never considered switching to lead free before, but we hope to help you make an informed decision.

The reason we are even talking about this is because of the Restriction of Hazardous Substances directive. RoHS was adopted in February 2003 by the European Union; all electronics sold there must comply. The substances restricted are: lead, mercury, cadmium, chromium VI also known as hexavalent chromium plating, and pbb, pbde flame retardants used in plastics. We will focus on lead. Solder joints must contain less than 0.1% lead to be compliant. RoHS is not currently required in the US, but California RoHS, effective September 2003, had a compliance deadline of January 2007.

Although the electronics industry has been directly targeted it only accounts for a small percentage of the lead used in manufacturing. The battery industry consumes nearly 80% of manufactured lead. Tire wheel weights also account for a larger percentage.

There are some good reasons for the hobbyist to convert to lead free solder, both personal safety and environmental. Lead poisoning can occur when lead enters the body through inhalation, ingestion or dermal contact such as direct contact to mouth, nose, eyes, and skin lesions. Even if you keep using tin/lead solder, wash your hands before and after you do anything. Most poisoning cases are from lead building up over time. The main environmental issue is lead leaching into drinking water or watersheds when disposed of improperly.

There are many different varieties of lead free solder. Two alloys seem be the most popular: SAC305 contains 96.5% tin, 3% silver, and 0.5% copper and melts at ~217C, SN100 contains 99.3% tin, 0.6% copper, and some nickel and silver and melts at ~228C. Choose whatever alloy and brand you feel is appropriate for you. Compare those alloys to traditional 63% tin and 37% lead melts that melts at ~183C. The higher melting point is part of what makes lead free harder to work with. We use SAC305 with a “no clean” flux core.

In addition to picking an alloy, you also need to decide on the diameter. We recommend for through hole .032″,.020″ and .015″ for SMT. Choosing the right diameter solder is very important to success. A finished joint viewed from the side should look like a little Hershey’s kiss, not an inflated balloon. The correct diameter solder makes this much easier to control.

A high wattage soldering iron with temperature adjustment is the best choice for precision work. Get a soldering iron with several sizes of replaceable tips for different soldering applications. Having a good iron makes soldering with lead free easier because of the higher melting point. It also helps to keep the dwell time as short as possible reducing damage to components caused by excessive heat.

Choosing the correct size tip for the job is perhaps the most important part for a new person learning to solder. Lead-free is less forgiving and the right tip will go a long way in preventing defects.

Using a tip that is too small will take longer, abuse the tip, and will not efficiently transfer heat to the joint. A small tip will seem too cold or too slow.

Using a tip that is too large will damage the circuit board, over heat and damage the parts, and burn off the flux too soon causing a bad joint.

Use tips that are designed for lead-free. Tips designed for lead free will have the longest life. The iron temperature should be set to 700-800F. Do not use pressure to compensate for lack of wetting and heat transfer; this will cause damage to the circuit board. Heat transfer is optimized by providing the best contact area.

Differences from tin/lead soldering

Tin/lead solder should not be mixed with lead free solder because it decreases the strength of the joint. Lead free parts can be used with tin/lead solder. You should try ordering all parts, ICs, resistors, caps, proto boards, etc. lead free even if you are not using lead free solder yet. This will ease the conversion for you in the future. Consumables such as flux and tip cleaner should be certified for lead free soldering. Flux will need to withstand higher temperatures and longer dwell times, and some tip cleaners have tin/lead solder in them that could contaminate the lead free solder joints.

Not all fluxes are capable of sustaining high soldering temperatures. Flux charring, called “black tip syndrome”, occurs when thermally incapable fluxes turn the tip black and make re-tinning nearly impossible. Heat transfer is severely reduced when this happens. Buying compatible flux is key.

As we’ve said many times: you’ll need to set your solder iron slightly higher temperature than you are used to. You will also notice that slightly longer dwell times are needed because of higher melting points. Wetting or spread is also a little slower when compared to tin/lead. The resulting lead free solder joints will appear slightly grainy and dull compared to shiny tin/lead.

The iron must be kept clean and fully coated with the solder alloy, otherwise at the higher temps oxidation can occur. Solder tips will need to be cleaned and tinned more frequently. Use a wet sponge for cleaning and keep your tip tinned by adding a small amount of solder. In general, all tips will have a reduced life when using lead free alloys.

Lead free solder is more prone to solder bridges (shorts). Tin whisker growth is also possible with high tin alloys, but is poorly understood.

The temperatures required make lead free soldering a different experience, but not out of reach. If you can solder with tin/lead solder, you can solder lead free. If you are having problems soldering, maybe some of the tips here will help. Remember, soldering takes practice; solder, desolder, resolder some old circuit boards from computers or consumer electronics before attempting a project. Otherwise you can’t expect a perfect outcome. Knowledge, practice and experience will provide the consistency required for excellent hand soldering results. Please share any experiences you have working lead free.

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.