Instructables
Picture of Connect robotic wheels to your old laptop
Do you have an old laptop just laying around, while you use your shiny new one to play WoW and surf the interweb? Have you ever thought "I would like to bolt some wheels on that old laptop and drive it around"? Perhaps you'd just like a mobile low-angle camera tripod. Maybe, you're the kind of person who wants to post videos of driving underneath a moving police car on YouTube. Well, if so, then this may be for you.

I was recently playing with my original LaptopWheels robotic platform, that I had built from some old pine tongue-and-groove shelving, and it got stuck in the carpet in my living room because the motors driving the wheels were too weak. I decided that it was time to rebuild it, better, and to share the build process here.

 
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Step 1: Gather tools

Picture of Gather tools
Tools Needed:

Wire Strippers
Scissors
Tin Snips
Tape Measure
#1 Philips Screwdriver
#2 Philips Screwdriver
Flat-Blade Screwdriver
Needle-Nose Pliers
X-Acto knife
Sharpie Marker
1/4" Nut Driver
3/8" Nut Driver
Drill, with a full set of bits
Soldering Kit
Metal Saw (Hacksaw, Jigsaw, reciprocating saw, etc.)
Straight-edge
Scrap wood, for sawing jig, and clamps
I was wondering, are the yellow wheels the ones you ordered? Where did you buy your wheels from? What rpm are your wheels running at?
psymansays (author)  snowluck23451 year ago
http://myworld.ebay.com/redingtoncounters

They run at varying RPM's depending on the speed command. I think they max out at about 120 RPM's, if I was just taking a guess. I haven't checked in any accurate way, I just think they may turn two full turns in a second.
psymansays (author)  snowluck23451 year ago
I bought them from an ebay user "redingtoncounters". Actually, they do not appear to be selling them any more. I would not really recommend them either. They took well over two weeks to ship, and when I e-mailed the seller to get status, they apparently didn't appreciate that, and they wouldn't allow me to place further orders when I was going to buy more of the same. They had blocked me on eBay. However, similar wheels are available from other sellers.
kburman3 years ago
Can your software can control servo directly from usb. Actually i have 2 servo and and a car which can move in omni direction i have developed a program in "Roborealm" which can follow a line and follow a ball but you know that can not  directly connect a servo or motor and the problem is that i have no board or PIC controller through which i can connect to computer and control it. So if your software can do this can you please mail me i will really very thankful to you or if you know any other way to do this please  tell me .Thanks In advance 
At last you have done a great project its really cool.I was thinking that if i had one with me.
psymansays (author)  kburman3 years ago
My system also uses a board in between the PC and the motors and servos, that the PC communicates with over a serial port.

Now, if you have a PC with a parallel port (virtually no modern laptop PC's have these, built-in) then you could program the parallel port to control servos directly, but otherwise, you do need a microprocessor.

One thing to keep in mind is that you can use an Atmel ATtiny2313 chip with almost no extra parts, which costs only $2.47 per chip, and you can program this chip with free gnu tools. (http://microcontrollershop.com/product_info.php?products_id=993)

You could make it as simple as taping the chip up-side-down to the top of your servo, and soldering directly to the pins (dead-bugging the chip)

AVR Freaks is an online forum with a lot of great resources for programming those chips, especially with servos.
OMG when i click on checkout button i was stuned to see $2.47 was converted into $32.42. It will be better to use parallel port can you please give a link to it tutorial.
fchfdhf.PNG
psymansays (author)  kburman3 years ago
Wow, I had no idea international shipping was so crazy expensive! (Especially for such a small part)

When I bought chips from that same web site, for shipping here in the USA, the shipping was like $2.

Well, don't get discouraged. Look up "Atmel ATtiny2313" and your country's name, and find a more local online shop.

The USB-to-Parallel adaptors, unfortunately, are much less programmable than an old Parallel port that was controlled by the PC BIOS. They won't work with any of the existing code or tutorials I know of. If you can get a PCMCIA Parallel port card, that can be made to work, though. I've used one of those for some hacky projects before.
Is there any way control even few LED's with USB to Parallel port converter
psymansays (author)  kburman3 years ago
You might be able to control up to 8 LED's with one of those USB-to-Parallel cords. Basically, you would have to trick your PC into installing a "Generic Printer (Text Only)" driver for the port, then any data that you try to "print" on it would be applied to the Data pins (D0 through D7) which you could plug a D-Sub connector with LED's on it into. It would be best to get a USB to DB-25 cable, otherwise you will have to work with the old Centronics standard 32-pin port.

To clarify, that is (http://en.wikipedia.org/wiki/D-subminiature) vs (http://en.wikipedia.org/wiki/File:Centronics.jpg) end connector.
Controlling 8 LED's more then i expected .
So,i install "Generic Printer(Text Only)" and then connect a LED's from pin9,29 and then print a page but nothing happen(sorry i forgot to mention that i have 36pin parallel port and i get pinout connection from "http://hw-server.com/files/lpt/download/piny.html")
Capture.PNGCapture1.PNG
psymansays (author)  kburman3 years ago
I decided to try this out myself, and take some photos. When I hooked up the USB-to-DB25 adaptor that I have to this circuit, the LED was actually lit when the port was idle, and not printing. This is because the operating system and the USB device firmware use 0xFF (255 in decimal) as the parallel port's data pins' idle state. In one photo, I turned off my spotlight, so that you can (dimly) see the LED lit up.
PICT0192.JPGPICT0193.JPG
Let me explain what i want to do.
I want to build a car which can follow any object. For that i need some thing which you have done above.Since i am fitting nettop in place of laptop as you have done in your projeect and nettop not have any port except USB.(So,no other option other than USB To Parallel port(Please don't ask for any MCU))
I want to control LED'S from USB TO Parallel port because if i can control Led from computer then i can control transistor then relay and almost everything(Like my Car Motor).
As you have done above i also done and found that it has very less power to control LED(or Transistor).
If you don't mind i want to ask one more question
like LPT1 has address Address: 0x378H or in VB Express &H378S
Is there any for USB001 {"http://www.instructables.com/files/deriv/FKA/89HD/GGPETDCS/FKA89HDGGPETDCS.LARGE.jpg}
You can see USB001 port at window titile as "Generic /Text_Only Properties "
psymansays (author)  kburman3 years ago
OK. Well, LED's are one-directional (the longer pin takes the positive voltage), and you should use a resistor in series with the LED (330 ohm, since the port is 5V). Another thing is, you should try running the circuit between Pin 2 and one of the ground pins instead of pin 9, because bit 7 (Data pin "8") will never be positive when you're printing normal text characters, but bit 0 (Data pin "1") will be positive about half of the time and negative the other half of the time. When you use windows to print to the port, the data will only be on the pins for less time than you will probably be able to see (microseconds) before changing to each next character and then being finished.
Atmel are really very cheap i am going to buy it. Site which you have give is that genuine because from that i am going to purchasing it .
I have a laptop with USB port but i have seen a Parallel to USB converter means that i have parallel port in my laptop .Is there any tutorial for it how to control servo from Parallel port and Can you give me the name of the free gnu tool. So that i can download it.
Thanks for all your help.
smegger4 years ago
 I love how you've really tried and succeeded to make this nice and simple, oh, and cheap of course! I have a MOSFET lying around and two 300w motors (same as yours pretty much- the one from your newest video) and some wheels similar to your drive wheel- check my electric trike instructable. Reason for all those parts-- I stripped my electric trike!

I almost want to do what you've done here because it just a whole other different aspect from what i've done- definately needs a web cam strapped to it too!

Nice one man
psymansays (author)  smegger4 years ago
 Thank you for you interest in this project; it's really rewarding to inspire people with similar interests. I'll check out your trike project, soon.

If you do decide to build something like this, I'd like to see it in action.
smegger smegger4 years ago
 MOSFET Controller*****
jaxxster15 years ago
Where can i scavenge the parts on the cheap?
psymansays (author)  jaxxster15 years ago
Well, you could start with finding some obsolete computer printers (maybe at a thrift store, or yard sales), and get all the motors, belt, and gears you can from those. Next, don't buy plexi-glass or aluminum parts, use scrap wood (for your first built, at least).

You can scale down the microprocessor by using the ghetto development tutorial for the $1-2 AVR micros. The web site microcontroller pros got me what I needed for an AVR set up for really cheap; just a DB25 connector, a 20-pin socket, and some ATTiny2313 MCU's at a very low price.

A great place for other parts is goldmine electronics; I got sprockets from there for about $1 each, and lots of other stuff is cheap there. I also would check out your local "Dollar Store" to see if you can use anything from there for materials.

The hardest part to get for cheap, is the motor drivers. Mine cost nearly $20 each in electronics, after shipping, from Mouser.com. I wan't able to come up with any alternate sources for high-current H-Bridges, than building them from scratch. Some people have good luck using off-the-shelf ESC units, but those are more like $50-$100, AFAIK.

Anyway, good luck. Let me know if you decide to build something; I'd love to see it.
thnks!
psymansays (author)  jaxxster14 years ago
No problem, buddy.
p.s. can you please send me your current state software? i am going to try to build it.
mspark4005 years ago
great job and a great project! cheers, mspark400
psymansays (author)  mspark4005 years ago
Hey, thank you for the encouragement.