Hack-a-Day

Capacitive discharge cutting provides more control than linear transformer versions. A very large capacitor is charged to a precise voltage and then discharged through the material to produce a controlled cut. The same device can also be used for spot and tab welding. A video of copper roof flashing being cut is embedded below. An example of a linear transformer can be found in our our How-to: build your own spot welder.

This antenna tuner is controlled remotely using geared motors and legos. The tuner needed to be closer to the antenna for performance reasons. This created a problem; most of the radio gear is inside while the tuner is outside. The gear motors and Legos combine to form a closed loop servo, operating two air core caps and an inductor switch. A control box placed near the radio is hard wired to the modded tuner outside. We would like to see something like this under gesture control using the Wii MotionPlus + Arduino.

Today is the last day to pre-order a Bus Pirate. Get your own Bus Pirate, fully assembled and shipped worldwide, for only $30. We don’t plan to make more soon, this could be your last chance.

A special shout out to our partner, Seeed Studio, who handled the rush of orders like pros. The first pre-order is already being manufactured, and will ship as soon as possible. Seeed still has a few V2a PCBs if you’d like to roll your own Bus Pirate.

You’ve made this pre-order a huge success, and we’d like to make more projects available in the future. Were you just interested in the Bus Pirate? Should we arrange pre-orders of future Hack a Day hardware? Are there any past projects that we should revisit?

Thanks for the artwork [Aaron], licensed under Creative Commons Attribution 3.0.

Here’s an interesting concept, the bot pictured above has no internal control mechanisms.  His claims to have built the smallest bot are dubious, considering it requires a much larger control platform to function, so lets just set that aside and look at how it works. The bot itself is basically a hollow box with a hinged manipulator mounted on it. He has then built a modified CNC type structure with various magnets below a platform. The magnets can move the bot and control the manipulator (assuming the bot isn’t trying to pick up anything magnetic). He talks about this being a possible control scheme for smaller bots, though we think he would have to make some major advancements to his magnetic controls for accuracy’s sake. As for his claims of being the smallest, well, we’re sure we’ve seem similarly sized bots, even hexapods,  that were completely self contained.

Here’s something every office probably needs. Ours does at least. It’s a WTF counter. When the office gets just a little too weird, someone hits the button and it gets logged. It’s probably pretty easy to judge the day by the WTF chart. The button is connected to an Arduino that updates the status on a local web server. We can imagine a nice bar graph of WTFs per day, or possibly a pie chart with normal time vs WTF time. Unfortunately, imagining is all we’re going to do. They didn’t include any examples of the visualizations. Can you imagine saying something to a co worker just for them to promptly march over and slap the WTF button? Maybe we don’t need one.

SparkFun has started to release some of their kits as open-source hardware. Projects such as ClockIt, a simple alarm clock, have their schematics, board designs, and source code released under the CC-by-sa license. Although most of their widgets and projects already had example code and schematics available, they are now using an open-source license. They are joining adafruit and EMSL and others in pushing OSH, but it is interesting to see an established company turn to this. Normally, startups do this to encourage early adoption.

[via adafruit]

[Jen Hui Liao] created a device that guides the user into drawing a portrait of themselves. Dubbed Self-Portrait Machine, it comments on how much in society is created by machines and we are dependent on them. Unlike previous drawing robots, the user is part of the sketching process. The machine holds the users hands and uses stepper motors and servos to move them around like a LOGO turtle. Liao promises to have more details available soon. Video of the machine after the jump.

Lifehacker wrote a guide for cracking a WiFi network’s WEP password using BackTrack. BackTrack is a Linux live CD used for security testing and comes with the tools needed to break WEP. Not just any wireless card will work for this; you need one that supports packet injection. The crack works by collecting legitimate packets then replaying them several times in order to generate data. They point out that this method can be hit-or-miss, especially if there are few other users on the network, as the crack requires authenticated packets. We covered cracking WEP before, but using BackTrack should smooth out compatibility issues.

Scratchbot is designed as a rescue bot, going places where there is low visibility. It’s defining feature is the fact that it uses “whiskers” to feel for things. We feel like this is a little gimmicky. If it is a low visibility situation, wouldn’t IR or audio, possibly sonar be a more effective? How would it differentiate between different physical obstacles? Are the whiskers really new? Aren’t they really just bump sensors? Maybe they have something a little more complicated going on. There was another recent bot that utilized whiskers and compared different tactile profiles to determine what it was touching.

A probe cable makes it easy to connect the Bus Pirate to a circuit and get hacking. Good test clips make quick connections on cramped PCBs without causing short circuits. We made two cables for the Bus Pirate v2, keep reading for an overview of our designs and list of part suppliers.

Friday, July 3, 2009 is the last day to pre-order a Bus Pirate. There’s only two days left to get your own Bus Pirate, fully assembled and shipped worldwide, for only $30.

Overview

We use these cables to connect the Bus Pirate’s I/O pins to a microchip or test circuit. A cable consists of a 2×5 connector, a cable, and some kind of attachable probe like an alligator clip or test hook.

The gray cable (top) is a ‘junk box’ cable, we recycled it from scrap parts and old computer hardware. The ‘expensive’ cable (bottom) uses high quality and special-order parts.

2×5pin female connector

The Bus Pirate’s I/O header is two rows of five 0.1″ spaced pins. We used a 2×5 arrangement because 2×5pin female ribbon cable connectors are common and cheap. We decided against a single row of 10 pins because the connector is an expensive specialty item.

The pin names are shown above, and are silk-screened on the bottom of the PCB. See the Bus Pirate page for detailed descriptions of each pin function.

The junk box cable uses a 2×5pin female connector from an old PC ISA card.

The expensive cable uses a black connector with a reinforced cable holder. Mouser has gray connectors ($0.69) and black connectors ($1.15).

Ribbon cable connectors have internal pins that pierce the cable when the top part is pressed onto the bottom part.

Ribbon cable

Standard 2×5pin female connectors attach to 0.05″ 10-strand ribbon cable. The wire thickness is usually 22, 24, or 26 AWG. We think 12inches (30cm) is a useful length that doesn’t get in the way.

Grey ribbon cable is pretty common. We salvaged a piece from an old computer connector, you might get lucky and find one with a 2×5 connector already attached.

A color coded cable makes it easy to identify each connection. DigiKey has 5 foot sections ($3.03), Mouser has it by the foot ($1.16, $1.19).

Ribbon cable is cheap and readily available, but it tends to tangle and kink. A really nice probe could use a ribbon cable stub attached to thicker test leads.

Test clips

Test clips are the most important part of the cable. They have to be easy to position, and maintain contact with the circuit. Alligator clips work, but there’s a lot of exposed metal that can create short circuits. Professional test clips have a grabber that retracts into the probe leaving less metal exposed.

Alligator clips

The junk box cable has alligator clip probes, we pulled them off test leads like these (40 leads for $12). You could also use loose red and black clips (20 for $2.30).

Remember to put the rubber housing on the cable before soldering the wire to the alligator clip, it won’t go on later. In the photos you can see that some of our covers are cut to fit over the front of the clip because we forgot.

Round test hooks

This is the classic, round-bodied test hook. These are great for grabbing onto 0.1″ pin headers, wires, and the leads of through-hole components. The hooks are usually too big to use with surface mount components, and the round body makes it hard to fit more than a few in a small space.

Test hooks are easy to position. Squeeze the probe to extend a single metal hook, grab something, then release. The hook retracts into the body of the probe, securing it in place and preventing short circuits.

Most hooks come apart by pulling the top away from the body. Put the test lead through the hole in the cap and solder it to the metal tab. Push the halves together when the joint is cool.

DigiKey ($17.26) and Fry’s ($14.95) have multi-colored hooks in sets of 10. Deal Extreme has dirt-cheap 10 packs of yellow ($2.30)  and black ($2.33) hooks, but the reviews say the quality matches the price so buy extra (via [haku]).

Flat test tweezers

Tweezer-probes are great for clipping onto the legs of through-hole, surface mount, and many smaller chips. They usually have a flat body so they fit better in tight spaces than round hook probes.

This type of probe has tiny tweezers instead of a hook. Accidental short circuits are rare because there’s so little exposed metal when the tweezers retract.

Most tweezer-probes pull apart and have a metal solder tab inside. Run a cable strand through the hole in the cap, solder it to the metal tab, and then press the halves back together.

Tweezer quality varies dramatically among brands, we’ve used no-name probes that bend easily or don’t grip well. The X- series micro-hooks from E-Z-Hook are the Cadillac of tweezer-probes, we first used the XKM version that comes with the Saleae Logic. They’re intended to fit specialty test leads, but it’s easy to solder a wire to them instead. About $2 each, available directly from the E-Z-Hook website.

Conclusion

We highly recommend a cable with hook or tweezer-probes for secure connections without causing shorts. The right probe depends on the parts you use. Round test hooks work best with through-hole parts and wires. Flat test tweezers attach well to small, surface mount chips.

Please share any additional part sources in the comments. We did our best to provide a variety of sources, but there’s going to be some great places we’ve missed.

Friday, July 3, 2009 is the last day to pre-order a Bus Pirate. There’s only two days left to get your own Bus Pirate, fully assembled and shipped worldwide, for only $30.

Stairs are one of the most commonly faced mobility challenges for a robot. This robot’s design eliminates the need for a complex drive train or computer, and instead uses a clever mechanical design to climb stairs. Version three of the robot uses five servos modified for continuous rotation, a Picaxe28, sharp IR sensors, and bump sensors.

[via BotJunkie]

The Great Internet Migratory Box of Electronics Junk, or T.G.I.M.B.O.E.J. has turned one. In the last year, they’ve learned a lot of things. They learned that lots of people are willing to contribute. Hundreds have signed up on the site to participate. Theyve also learned that laziness is the key road block on this project. The boxes that have stalled generally sitcollecting dust, simply because someone hasn’t bothered to ship it off. If you’re curious what kinds of stuff ends up in one of these, check our initial post. There aren’t any guarantees though, it all depends on what people toss in.

Using an IR thermometer, there are two ways to go about building a thermographic camera. The first uses a pan and tilt head. Scan lines are emulated, as a computer controls panning from left to right, taking a temperature sample from each step. Vertical resolution is accomplished by tilting. Another method uses a web cam attached to the thermometer. The thermometer’s laser pointer is captured with temperature annotations, as the computer records the field of view. We think the best outcome can be found with a combination of both methods. The video embedded below demonstrates the results. This would be a good addition to the Autonomous paintball sentry.

[Thanks Rolf]

With the 4th of July around the corner, we thought it would be a good idea to give a controller wrap up and show you how to make some ignitors. Last year we covered a microcontroller based fireworks launcher. If you like the idea of a controller but don’t want to run all the wire, we have the wireless fireworks controller. Adding a little twist to the wireless scene are cell phone triggered fireworks. Maybe controllers are not your cup of tea, you could try to microwave your fireworks. After the break we show you how to make ignitors from a diode and a match.

Using a 1N914 diode, match, and 4 ohm ballast you can make your own ignitors. Using the leads for support, the diode is attached to the match. A current is passed through the device to cause rapid heating. The match head and component must touch one another, in order to ignite. In the video embedded below we show you exactly how.

DARPA has awarded an extension to AeroVironment for their work on the Nano Air Vehicle project.  The prototype seen above, called Mercury, is an ornithopter which means it flaps it’s wings. It is the first to show controlled hovering. Look closely, there’s no rudder or tail. Mercury uses the two wings for both lift and control. Ornithopters themselves aren’t new, we’ve even covered them before. Usually they use the flapping wings for propulson and a tail to steer as they travel like an airplane. We would really love to see some detail shots of Mercury.

[via slashdot]

[Kyle McDonald] sent in his latest project, a software keylogger that twitters what you type. He wrote it using C++ and OpenFrameworks. It logs each keystroke, then it posts to twitter 140 characters at a time. To protect himself, he set up a whitelist of private strings like passwords and credit card numbers that would be stripped before posting. If the twypewriter followed him, his keystrokes could be recreated.

[thanks Kyle]

Most of the parts we use operate at 3.3volts, but we still run into a lot of old 5volt stuff, and an occasional 2.5volt or 1.8volt part. This post explains how to use the Bus Pirate’s open collector pin mode to interface with parts at different voltages.

We’ve got more details and some example scenarios below the break. Yup, this is another Bus Pirate post. It’ll all be over soon though, because there’s a few days left to get your own Bus Pirate for $30, fully assembled and shipped worldwide.

Overview

The Bus Pirate has a normal pin mode and an open collector pin mode (also called high-impedance or HiZ). Normal pin mode can tolerate up to 5.5volts on input pins, but the output pins are fixed at 3.3volts. The open collector pin mode uses a pull-up resistor to set the bus voltage to something other than 3.3volts. Normal or open collector pin mode is offered as a configuration option after you select a protocol library in the Bus Pirate terminal (menu m). Some bus types always require open collector outputs with pull-up resistors, like 1-wire and I2C.

The image above shows a representation of normal and open collector pin functions.

Normal pin mode

Normal pins switch between the positive supply voltage (high state, usually 1) and ground (low state, usually 0), in the Bus Pirate that’s 3.3volts and 0volts respectively. A normal pin is depicted on the left, switch 1 (S1) toggles the output between supply (V+) and ground (GND).

Open collector mode

In open collector mode, pins switch between a ‘disconnected’ state (high impedance) and ground (low state, usually 0). The voltage that signals a high state is supplied by a pull-up resistor (R1). Without a pull-up resistor the attached devices will never register a high state. We can feed any voltage into the pull-up resistors that the Bus Pirate will tolerate, so we can use this mode to interface devices above and below 3.3volts.

An open collector output is depicted on the right. Switch 2 (S2) can only connect to ground. A resistor (R1) connected to the supply voltage (V+) holds the bus high. Most microcontroller pins are tri-state and become high impedance when configured as an input.

This technique isn’t without disadvantages. The maximum possible bus speed is much lower, and the pull-up resistors use a bit of extra current. Make sure every device you connect can tolerate the voltage you plan to use, most 3.3volt devices don’t have 5volt tolerant pins.

Usage examples

Scenario 1 – Bus Pirate interfacing 3.3volt UART/SPI/JTAG/MIDI bus
The Bus Pirate operates at 3.3volts, use normal pin outputs with no pull-up resistors.

Scenario 2 – Bus Pirate interfacing 5volt UART/SPI/JTAG/MIDI bus
The Bus pirate inputs are 5volt tolerant, but the output is only at 3.3volts. Use open collector outputs (HiZ) with pull-up resistors connected to the 5volt power supply.

Scenario 3 – Bus Pirate interfacing 2volt UART/SPI/JTAG/MIDI bus
The Bus pirate output is 3.3volts, which might damage a 2volt part. Use open collector outputs (HiZ) with pull-up resistors connected to the 2volt power supply.

Scenario 4 – Bus Pirate interfacing a 1-wire or I2C bus between 1.8volts and 5volts
1-wire and I2C are bi-directional, open collector buses. They always require a pull-up resistor to create the high bus state. Use pull-up resistors connected to the 1.8volt to 5volt power supply.

Snow days are great, but generally you still have to wake up to find out if it is a snow day. [insingertech] decided to make a system to solve this problem. He made an alarm clock that would automatically de activate if school is cancelled. What a pleasant surprise it would be to just wake up and find that you had been allowed to sleep in. It is using an Arduino and a python script to control the state of the alarm based off of an online school closing announcement. You can download the software from the instructable.

[Michael] has a keypad in his previous car’s door and he missed it enough to hack one into his Dodge Caliber. He bought a Ford keypad and mounted it inside his door with some custom electronics. He started with an Arduino nano to receive and authenticate button presses. This then splices into wires in the door that control the door lock. The program has a 5-digit code to unlock the door, but simply pressing 1 twice will lock the doors. He also implemented a lockout feature to prevent people from brute-forcing the combination. Although it isn’t wireless, it’s significantly simpler.

[thanks Michael]

The folks over at basicmicro.com are working on a massive LED display. They currently have one 32×32 RGB panel working. It displays 50 fps at  140 hz but the one above is only running at about 24 fps. The final display will be 40 of these panels. This thing is going to be massive. We have to wonder how this compares, financially and performance wise, to the commercial signage that displays videos.