Wandering aimlessly through that great and tangled web we call the Web, I discovered the Den of Iniquity , where we are invited to perform the following:

1. Grab the nearest book.
2. Open the book to page 123.
3. Find the fifth sentence.
4. Post the text of the sentence in your journal along with these instructions.
5. Don't search around and look for the "coolest" book you can find. Do what’s actually next to you

"You can readily identify mating phases when there is a small resistance though the wire pair." From Robot Builder's Bonanza , first edition, by Gordon McComb. It was under some papers, a Linux Journal , and the AS&S catalog.

In this section of the book, the author discusses stepper motors. Unlike a typical DC motor, the coils of a stepper motor must be energized in a specific sequence for the motor to turn. Although this means that the controlling circuity must be more complex, the stepper motor's motion can be more precisely controlled, and can supply more torque at lower speeds. Thus they are ideal for devices that must move to precise positions, such as in floppy disk drives . Hmm, do people still those? I guess not.

An ideal application of stepper motors is in robotics. For example, in something I've wanted to build for quite a while, a CNC machine . This is basically a robot that operates a power tool, typically a drill or router, but sometimes an etching laser, a water jet cutter, a pen, icing dispenser, or whatever the situation calls for. In fact, a fabricator is basically the same sort of machine, but with a tool that deposits material (or hardens plastic ), rather than cutting material away.

The reason the CNC machine had bubbled to the top of the stack is because I was recently seized by a desire to build a telescope. It would certainly be nice to make the robot do all the fiddly cutting and drilling, which, if I were to do by hand, would almost certainly introduce enough slop to render the entire device useleless. Of course, stepper motors would have their uses here as well, in the positioning of the scope and the accounting for the motion of the Earth.

And when all was said and done, I could then torment visitors with photos like the following, and the tales of all the stepper motors that made it possible.

Jupiter

Originally uploaded by astroferg .

I've often wondered what's in it for denouncers of global warming. Now we know. Are we really surprised that Big Oil is pulling the strings from that side of the debate? We all know that they stand to lose big if legislative action is taken in reaction to climate change. Now, what's in it for those on the other side of the debate? Well, who stands to lose big if no action is taken? That would be agriculture and tourism. I guess we'll soon find out which industry can scream the loudest.

In other political linkage, check out this interesting poster of the Federal budget, which makes it easy to visualize your tax dollars at work. We certainly no longer spend more on space exploration than on law enforcement.

In meaningless linkage, here is an analysis of how the later three Star Wars movies changed the meaning of the earlier three movies.

Never Confuse a Memo With Reality: And Other Business Lessons Too Simple Not To Know

It's funny how one can start searching for one thing and end up finding something else.

For example, one could search for android-related information, but a typo could cause one to recall the word androne. This might have been one of many games for the Tandy Color Computer At this point, one might be overcome with nostalgia for a beloved 8-bit microcomputer , and peruse the entries for one's other favorites, such as Popcorn , Polaris , Microbes , Panic Button , Spidercide, the oddly unmentioned Robot Odyssey, and of course the (in)famous Dungeons of Daggorath .

One might sigh with regret at this point, recalling one's long-vanished CoCo2 and Program Paks therefore, but one might also breathe a sigh of joy to learn that modern reimplementations exist of both Robot Odyssey (as DroidQuest ) and of Dungeons of Daggorath.

I count myself lucky, actually, to have received a CoCo2 for my ninth birthday. I think that if I'd been given a more mainstream system, such as a Commodore 64, an Apple II, or even an IBM-PC, the ready availability of software for these systems would have led me to spend most of my time playing games written by others. Instead, I read lots of books on how to write games in BASIC and laboriously translated the examples therein to the proper dialect. As a result, I learned not just "how to work a computer" but how a computer works .

San Diego is now ranked as 21st Fattest City in America .

In other news, here are some motivational posters for Role Playing Gamers.

And here's my word cloud:

Rather than posting another Robot Update that says nothing of importance except that it's been a while since the last Robot Update, we're going to try a something new, a question-and-answer column! Now, since nobody's actually asked me anything directly yet, I'll instead respond to a hot(ish) search topic.

Q. Control cordless drill motor with basic stamp

A. Although your query was phrased less than elegantly, I'll attempt to answer what I assume is a question. A pair of cordless drills or electric screwdrivers may be the ideal propulsion system for a combat robot. Consider the advantages: built-in gearbox, adjustable speed and torque, and modular, self-contained rechargeable battery packs. They can also be obtained for a relatively low cost, especially when compared to buying and/or fabricating the components separately. They can also be considered to be easily replaceable, another advantage to a combat robot.

Before we begin the interesting part of this article, I'd like to point out that I am not a professional electronic engineer, nor do I play one on television. This is also not a step-by-step tutorial on hacking your rechargeable drill. This is just me telling you very generally how I would go about doing it. It could work, but then again, it could explode in your face, set your house on fire, frighten your children, or just plain not work. I haven't actually tried it, so I don't know.

Still there? Good. Let's take a look at the guts of a cordless drill.

You'll notice that the on/off switch and the speed-controlling rheostat have been removed. That's fine, as I wouldn't be using them. You'll also notice that the battery jack and the case are missing. This is so that I can make a point. Below, you'll see the equivalent assembly from a remote-controlled dune buggy.

Notice anything? That's right, they're not all that different. So at least one way of controlling these motors should have just occurred to you. If you're building a remote-controlled combat robot, off-the-shelf RC controllers will probably fit the bill.

But since you also asked about BASIC Stamps, I assume you're going to want to program your robot, rather than just puppeteer it by remote control. That's fine, too. In that case, I'd build my favorite motor controller, the old-fashioned electromechanical H-bridge. I'd choose this over a transistorized or solid-state controller mainly because I don't know what voltage the drills will be using. Relays can typically handle 120V AC, so handling 12V-36V DC shouldn't be a problem. Also, the brushes of the motors can introduce a lot of noise into the power supply, and this method will physically isolate this noise from the control circuitry. And finally, listening for the clicking of the relays can be a valuable troubleshooting tool.

Here's the schematic.

Typical parts are 1K resistors, 2N2222 transistors, and 1N4003 diodes. I try to use 5V relays in order to avoid the need for a 6V or 12V power supply. However, if the design of your bot means that you already have a 6V or 12V bus, then by all means use it.

The finished product might look something like this.

There are, of course, some drawbacks to this circuit. The main drawback is that the motors will always run at a constant speed, as determined by the supply voltage. This may be what you want. However, a robot that can only go full speed ahead could be difficult to maneuver. I would suggest the following modification if you want speed control.

This version will use a big fat power transistor in place of the SPST relay. You could then feed a PWM signal from the BASIC Stamp to the transistor to control the motor's speed. I'm told the diode across the pins of the transistor is necessary to protect it from backlash voltage when the motor shuts off. Hopefully I've got it in the right place. Values of these parts depend on your motor.

The finished product might look something like this:

This concludes our first installment of q+=a. If you have a question you'd like answered, go ahead and leave it as a comment. Also, if you don't like my answer, go ahead and leave that as a comment. See you next time!

It's been a while since I've responded to a questionnaire. But I think one may be appropriate right about now, since I don't have anything snarky, pithy, sentimental, meaningful, or interesting to say about Valentine's Day-- except of course to wonder a) whether I'll see Easter Bunnies before I see leprechauns and b) whether I'll see either of them tomorrow.

Anyway, this questionnaire is brought to us by Comical Misadeventures of a Rambling Mind . The point of this questionnaire is simply to play the old word-association game. Here we go.

1. Cigarette: Smoker
2. Sex: Attention
3. Relationship: Pain-in-the-ass.
4. Ex: Lax
5. Power: Hungry
6. Create: Make
7. Job: Shovel
8. Food: Eat
9. Type: Writer
10. Home: Heart
11. Care: No
12. Value: Cost
13. Eve: Midsummer's
14. Jest: Jester's cap
15. Religion: Preacher
16. Thunder: Lightning
17. Fear: Love
18. Marriage: Wedding
19. Back: Front
20. Spark: Plug
21. Tear: Fabric (of the Spacetime Continuum)
22. Trust: Antitrust
23. Boredom: Without Technology
24. Inside: Intel
25. Fire: Caveman
26. Game: Gameboy
27. Soft: Ice Cream
28. Ice: Caves
29. Hard: Man (Hard Man was a Mega Man boss. I swear . Okay, fine, don't believe me then. What ever.)
30. Because: Just
31. Community: Bank (No, I don't use them.)
32. Wood: Man (Wood Man was another Mega Man character. Really. I am such a nerd. )
33. Theme: Park
34. Love: Hate
35. Hate: Joy
36. Friendship: Friendship? (Mortal Kombat. Nerd! Nerd!)
37. Money: Green
38. Heartache: Tonight (oh, no )
39. Lust: Envy (And I thought of the Homunculi. Nerd-nerd-nerd.)
40. Time: Space
41. Divorce: Rate

Something new has happened. Someone has written a post about me. An entire post! Sure, people write posts about each other all the time. But since this is kind of a first for me, I'm still going to find it exciting--.and interesting! In a remarkable coincidence, the other blogger's name is also Erik, and he's gay and a robot enthusiast. What are the chances of that?

Well, let's find out, shall we? A quick visit to howmanyofme.com reveals...

• There are 101,989 people in the U.S. with the first name Erik.
• Statistically the 518th most popular first name. (tied with 5 other first names)
• More than 99.9 percent of people with the first name Erik are male
• There are 299,968,595 people in the U.S.

So, what are the chances of being named Erik? Well, if you're female, the chances apparently approach zero. However, if you're male, which I assume exactly half of the population is, then the chances are 101,989:149,984,297, or approximately 1:1500, or 0.06%. That may seem low, but remember, it's the chances of being named Erik, not Eric (the 52nd most popular name.)

Next, a visit to Google reveals that nobody can quite agree on the percentage of the population that's gay. Depending on who is asked, what is asked, and how it's asked, the results seem to be anywhere between about 1% to 10%. Therefore there should be anywhere from 1.5 million to 15 million gay men in the U.S. But let's assume the correct answer is 5%, since it lies between the two extremes. That's 7.5 million, about 4,000 of which should be named Erik. The chances of that are 1:1875.

That's more than I would have thought, but I never claimed to be good at math. Rather I vaguely remember just enough to be dangerous.

Finally, what are the chances of someone being a robot enthusiast? On that subject I have found nothing. Surely there exists, no doubt behind some impermeable corporate firewall, some closely-guarded marketing demographic database that would quite plainly show that out of X customers, Y purchase robot-themed products. Certainly, Amazon and Google would both have such data. But I doubt either of them would tell me the answer without charging handsomely for the privilege of asking.

However, I've run a quick and dirty experiment which could vaguely amount to a survey. I did a search of Flickr profiles for "a" and "a robot"-- which is somewhat misleading since I, myself, don't have the word robot in my profile. In fact, it's pretty much blank and would thus have been excluded from this search. Anyway, the a-only search returned 72,519 members, and the a-robot search returned 607. I conclude that the chances of being a robot enthusiast are 0.83%. And therefore out of the previous 4,000 Eriks, only 33 will probably consider themselves robot enthusiasts.

Now, to find the other 31...

Some may say these Robotic Eyeballs are a bit on the creepy side. I'd like a couple for my desk at work.

Make brings us this Linear Stepper Motor Kit . Looks like a pretty good design that can handle some heavy-duty stepper motors.

My gaydar may blow but at least I can tell a serial killer from a programming language inventor nine out of ten times.

Welcome to the second installment of q+=a, The Electronic Replicant's new question-and-answer feature. As nobody has actually submitted a question yet, I'm going to consult my referral logs again.

Q. How can I control a 120VAC motor with a BASIC stamp?

A . This should not be too difficult if all you need to do is turn the motor on and off. Now, it is important to remember that I am not an electronic engineer, nor do I play one on television. I am also not an electrician, with which one really ought to consider consulting before trying to build anything that interfaces directly with wall current. The following ought to work, but it could just as easily electrocute you, catch fire, or otherwise malfunction. You're probably better off buying an X-10 module.

Still there? You are obviously an individual of unswayable fortitude, or perhaps you have simply fallen asleep at the keyboard. In either case, what you'll need is something along these lines:

This is quite similar to the motor controllers I mentioned last time. A pulse from the BASIC Stamp (or other microcontroller, or your PC, or whatever else) causes the LED side of the optocoupler to emit light and thus trigger the phototransistor side of the optocoupler. The transistor energizes the relay coil, creating a magnetic field which closes the contacts, allowing AC to flow from the plug to the socket, thus powering your motor, Christmas lights, fan, pump, or whatever.

A nice thing about this circuit is that the optocoupler will protect the Stamp or PC from destruction by high voltage if the relay happens to short, which is not likely, but it could happen if the current flowing through the contacts is much higher than what the relay is rated for. That could also lead to the relay melting and/or bursting into flame, which is just not a good thing. Of course, the optocoupler is really effective only if the PC and relay are on separate power supplies.

That concludes this installment of q+=a. If you've got a question you'd like answered, or if you think my answers are utterly and completely useless, or both, or neither, please leave a comment at the prompt.

Q. I've asked my friends to give me their broken appliances so that I could scavenge parts from them. Now I have so many circuit boards lying around that it takes me longer to look for a chip than it does to remove it from the board. How can I get more organized?

A. I had this same problem. The answer is to create a database. With the work of an hour or two, you'll soon have all your parts at your fingertips. And if you're a Windows user, chances are you may already have all the tools you need on your computer. I'm talking about MS Access. Sure, professional DBAs may scoff at this program, but it will be sufficient for cataloging a few hundred components. On the other hand, if you're an ambitious Linux user, you might be well-served to look into a Linux-Apache-MySQL-PHP (LAMP) solution. Whichever route you take, plenty of books and Web tutorials are available.

When I set up my database, I created tables for each sort of component I wished to track. For example, the IC table looks something like this:

The Container field points to a record in the Container table, which represents either a circuit board or other container (such as a drawer of loose components):

The Location field points to a record in the Location table, which represents the various boxes and drawers used for storing Containers:

Now if I ever need an L272M, or an Op-Amp in general, I can query the database, which will tell me that there's one on Brownish board marked LP1-CD MBD in Cardboard Box #1 .