555 Inductance Meter

February 25, 2011 by Mike Szczys 7 Comments

[Apexys] is performing some experiments with switched-mode power supplies and needed to compare the inductance of the coils he was using. His multimeter doesn’t have an inductance testing function, but he does have a 555 timer on hand. He put the 555 and some other parts together to create his own L meter. The writeup includes the theory behind this meter, with an incoming AC source converted to a voltage by an RC network.

Once he’d worked out the design it was time to build the circuit. Instead of printing a circuit board he created what he calls a DCB; Drawn Circuit Board. We’ve got to admit that this was way faster than using toner transfer or soldering point-to-point. We also like his use of an Erlenmeyer flask and a torch to heat the etchant. We don’t make PCBs in the winter because our Cupric Chloride is too cold to use outside but that may change now. The final piece in the puzzle is an analog meter which he pulled from an extra microamp meter he had on hand. Check out the demo after the break.

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A VFD Clock That Tells The Time, Then Tells You To **** Off

February 25, 2011 by Mike Nathan 12 Comments

Clocks are relatively simple devices – they tell time, and most often sport a handful of other utilitarian features like alarms and radios. Rarely though, do you see a clock that will wake you up in the morning and also curse at you shortly thereafter. [Matt Evans] clearly thought that clocks need to pack a little more attitude, so he built his girlfriend a clock that not only tells time, but spouts off nasty phrases as well. What a lucky gal!

The clock was constructed using IV-17 VFD tubes, each bearing 16 light-able segments. It seemed wasteful to simply use the tubes to tell time, so [Matt] got busy adding other features to the clock. It has an alarm, a calendar that is always stuck on his girlfriend’s birthday, and an ambient light sensor to dim the tubes at night. It also sports a variable rudeness setting, allowing for mild insults when family members are present, and extremely foul language for when your frat brothers swing by.

He has plenty of pictures on his site, but we’re betting people will want to see schematics and some source code. After all, Mother’s Day is but a few months away!

Propane Tank-ard

February 25, 2011 by Kevin Dady 22 Comments

[hpstoutharrow’s] new instructable is a neat idea on how to re-use those single use small propane bottles by turning it into an insulated canteen. Once the bottles are emptied through normal use, the safety valve is popped loose and allowed to vent. There are also comments on the article that suggest that the bottle be submerged to ensure all gas is gone, and we think that is wise too.

Once safe to work on, the bottom is cut open and the stem is cut off leaving a empty shell, a soda bottle is shrunk down by boiling water inside of it for a little bit, then is fit inside the propane bottle. The top of the soda bottle is held in place by an O-ring, the safety pressure hole plugged up and the whole thing is filled with spray “expand-o-foam” locking everything in place and adding insulation.

Though using a thermoplastic bottle as its liner does not invite hot beverages to the party, it seems to do the job just fine for cold drinks, and it makes for a interesting conversation piece out on the campground.

Join us after the break for a quick how-to video.

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A Look At Sony’s Ongoing War Against Hackers

February 25, 2011 by Mike Nathan 60 Comments

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[Phillip Torrone] recently wrote an article over at Make regarding Sony and their “War on Makers, Hackers, and Innovators“. In the article, he traces Sony’s history as a well-liked hardware company that once produced innovative products, to its current state as an enemy to all who would dare wield a screwdriver and soldering iron. He took quite a bit of time scouring the Internet to dig up very specific examples of Sony’s perceived assault on the hacking community. That’s not to say he simply lambasts the company and leaves it at that. Rather, he reflects on their past as a staple in nearly every American home, how they have changed since venturing into the content business, as well as what we might be able to do as hackers to change the way Sony treats its customers.

One specific example he mentions is the lawsuits that plagued the Sony Aibo modding scene, a case very near and dear to his heart. This scenario is one where the voice of the people was eventually heard, though too late to make a difference. He laments the loss of interest in the platform by the modding community as a clear cut example of the disastrous nature of Sony’s litigious nature.

You should definitely take a moment to read the article if you have the time. [Phillip] brings up some very good points, giving you plenty to consider the next time you make an electronics purchase, large or small.

We’d love to hear your take on the matter as well.

Racking Up Miles On A Bicycle Odometer

February 25, 2011 by Noah Dunker 27 Comments

[jonh] religiously tracks the miles he rides on his bicycle. When his odometer’s battery started getting low, he wanted a way to run the miles up to where they were before, since replacing the battery resets everything to zero. [jonh] used an Atmel microcontroller to run up the miles on his bike computer so he could pick right back up where he left off. There is definitely a Ferris Bueller’s Day Off joke in here somewhere.

The bike computer itself is designed to plug into a base that connects to a magnet-triggered reed relay. It uses a wheel-mounted magnet to count the number of revolutions made and thus the distance traveled. [jonh] hooked up a simple microcontroller-driven circuit to these connectors to trick the bike computer into thinking it was moving, and moving fast! Since he knew the number of miles he wanted to sandbag onto the odometer, he was able to program it to run up the proper amount of miles and then stop. There’s no source code listing for the project, but this shouldn’t be too hard to reproduce. He provides a pencil-drawn schematic for the connection to the cyclometer from the microcontroller. At the end, there’s also some sage advice for those of you who are interested in building a decent hardware hacking lab on the cheap.

Building A 555 Timer From Discrete Components

February 25, 2011 by Noah Dunker 18 Comments

The 555 Design Contest shook a whole bunch of really creative circuits out of the trees, hence the 555-heavy content lately. While not technically part of the contest, [esalazar] wanted to know what made the 555 tick, literally! He started working on the project in a circuit simulator, then ultimately ended up building the three main logic blocks inside the familiar timer on pieces of copper-clad board. He’d built a 555 using discrete components.

While this isn’t 100% compatible with the classic 555 IC, it covers the basics pretty well, and [esalazar] gets extra-credit points for embracing the hacker spirit of seeing for himself how stuff works while documenting it well and citing his references.

Digital Wavetable Oscillator

February 25, 2011 by Kevin Dady 9 Comments

The tabulaRasa is a digital wave table oscillator, and features control of frequency, wave table selection, and interpolation. The device is split up into 2 parts. One is a pcb with a healthy amount of resistors, 3 potentiometers, ST TL074 JFET op amp, atmega328 and a SD socket.

The second part is software for your computer that allows you to edit or create your own waveforms. There are 3 different modes of control. Breakpoints, which allows you to set the waveform points and allows up to sixteen. Harmonic allows amplitude control over 16 harmonically-related sine waves, finally, the third mode lets you load in short sound clips.

Once you’re happy, save to a SD card and pop it into the board, and you’re ready to make some noise. The project page states at the end “tabulaRasa is in the last stages of development, and will be available soon.” so you cant get your hands on one just yet, but if you’re interested [Greg] has a kickstarter page setup where you can find out details on pricing.