Back in 2007, [Stathack] rented an apartment in Thailand. This particular apartment didn’t include any Internet access. It turned out that getting a good connection would cost upwards of $100 per month, and also required a Thai identification card. Not wanting to be locked into a 12-month contract, [Stathack] decided to build himself a directional WiFi antenna to get free WiFi from a shop down the street.
The three main components of this build are a USB WiFi dongle, a baby bottle, and a parabolic Asian mesh wire spoon. The spoon is used as a reflector. The parabolic shape means that it will reflect radio signals to a specific focal point. The goal is to get the USB dongle as close to the focal point as possible. [Stathack] did a little bit of math and used a Cartesian equation to figure out the optimal location.
Once the location was determined, [Stathack] cut a hole in the mesh just big enough for the nipple of the small baby bottle. The USB dongle is housed inside of the bottle for weatherproofing. A hole is cut in the nipple for a USB cable. Everything is held together with electrical tape as needed.
[Stathack] leaves this antenna on his balcony aiming down the street. He was glad to find that he is easily able to pick up the WiFi signal from the shop down the street. He was also surprised to see that he can pick up signals from a high-rise building over 1km away. Not bad for an antenna made from a spoon and a baby bottle; plus it looks less threatening than some of the cantenna builds we’ve seen.
When your project is ready to build, it’s time to find a PCB manufacturer. There are tons of them out there, but for prototype purposes cheaper is usually better. [Ian] at Dangerous Prototypes has just announced Dirt Cheap Dirty Boards, a PCB fabrication service for times where quality doesn’t matter too much. [Ian] also discussed the service on the Dangerous Prototypes forum.
The boards are definitely cheap. $12 USD gets you ten 5 cm by 5 cm boards with 100% e-test and free worldwide shipping. You can even choose from a number of solder mask colors for no additional cost. [Ian] does warn the boards aren’t of the best quality, as you can tell in the Bus Pirate picture above. The silkscreen alignment has some issues, but for $1.2 a board, it’s hard to complain. After all, the site’s motto is “No bull, just crappy PCBs.”
The main downside of this service will be shipping time. While the Chinese fab house cranks out boards in two to four days, Hong Kong Post can take up to 30 days to deliver your boards. This isn’t ideal, but the price is right.
We love cheap stuff here. Who doesn’t? [Oscar Rodriguez Parra] does too, and wrote in to show us his super cheapey robot L.I.O.S. The build was for the AFRON design challenge, which involves building a 10 dollar robot to teach students robotics. The winners of the challenge were neat and all, but they all look too fancy flaunting their molded plastics and electronics breadboards.
[Oscar’s] design is super simple, LDRs as eyes, a PIC12F683 to do the brainin, LEDs for indicators and a couple modded servos to drive the wheels. An extraordinarily complex cardboard flap roller helps the cart turn, but probably isn’t going to see much aside from smooth flooring. The electronics are mounted using one of our favorite techniques, the paper perf board (very similar to the substrate free technique).
Check out the video after the jump to see LIOS in action. This is an excellent introduction to robotics for any classroom. Thanks [Oscar]!
Continue reading “L.I.O.S.: The ten-ish dollar robot.”
Like just about everyone else out there, [Adam] thinks that CNC machines are pretty cool – so cool that he decided to build one of his own from scratch.
The CNC machine was constructed mostly out of MDF and scrap wood, with drawer slides used for smooth gantry movement. An off-brand rotary tool was used to do the actual cutting, and [Adam] picked up a few Sparkfun stepper motors to drive the machine.
The assembly was completed without too much trouble, but [Adam] says that programming the mill was a long and frustrating process. Cutting was rough and not very accurate at first, but little by little he got things working pretty well. As you can see in the video below, while the cuts look great, improvement came at the expense of speed. He says that the machine could use a redesign to speed it up, which he’ll get around to if some free time comes his way.
It’s not the absolute cheapest CNC build we’ve seen, it’s pretty darn close. With a few tweaks, it could definitely be a solid budget-friendly contender.
Continue reading “$150 CNC mill is a tad slow but very solid”
A common complaints of beginners to microcontroller programming is the availability of DIY tools that do not require a parallel port. Using not much more than a couple of 74xx series chips and some protoboard, [Rue] was able to create an AVR programmer for less than the cost of some chips it can program – giving parallel programmers a run for thier money. [Rue] used Linux treat the ubiquitous PATA/IDE port as a parallel port. By having avrdude treat the programmer as an Atmel STK200, [Rue] was able to upload a blinky program to his AVR microcontroller through ISP. If anybody can think of an even lower cost unconventional solution give us a shout.
[Andrew] tipped us off about his Cable Cam built out of some lumber and clothes line. It is small enough to fit into a backpack, includes a safety line and the camera can pan and tilt. A future version is planned with a small remote motor to move the trolley more effectively.
[Andrew] accidentally linked us to his other Camera Crane, taking the same ‘cheap yet effective’ approach as his Cable Cam. Once again, just some lumber and creative engineering are used to pull this one off.
For those without the ability to weld, check out [Bill Van Loo’s] all wood version of a Camera Crane. Same parallelogram design, without remote video output or central pivot.
[AntonB] has modified a servo into a powerful linear actuator (think: changing rotational motion into linear motion). The process is simple enough, modify a servo for continuous rotation and then add the custom built actuating shaft. You do of course lose the precision of the servo, but a small price to pay to be able to lift ~20 pounds straight up. Inspiration for such a cheap solution came from his Planetary Surface Exploration Rover. Check out a video of both after the break.
Continue reading “Servo hacked linear actuator”