[Gio] enjoys using vacuum tubes in his projects. He designs the circuits using a CAD program but was finding that there is no substitute for actually building a prototype before heading to a final design. To make this process easier, he built his own tube prototyping station.

At the top of the board he’s got three different sizes of tube sockets with the pins from each wired as common. The nine pins from the sockets break out to a terminal strip where they can be interfaced with a solderless breadboard. For added versatility he’s included terminals to tap into some RCA jacks, as well as a 100 kOhm variable resistor. We’d bet this is not something that you can find ready-made, but it sure does look a whole lot better than a workbench full of components alligator-clipped together.

[Johndavid400] built this incredible looking R/C lawnmower. After spending some time repairing broken R/C cars, he wanted to move on to something a little more useful and powerful. He decided to build a mower. He’s using a transceiver set from ebay, with an Arduino interpreting the signal and outputting to his custom motor board. In the video after the break, you can see that the mower looks responsive and quick. He does note, however, that he had some glitches early in the process that left him with a runaway mower. We covered a very similar mower ages ago that used a wheelchair as the base.

[via littlebirdceo]

[Kizo] repurposed a flatbed scanner to use as an exposure box for making printed circuit boards. Exposure time is controlled by an AVR ATtiny2313 microcontroller. The device is connected to a separate display board to control four 7-segment displays using one shift register for each. Time is set in ten second increments and once started, switches on the lights with a relay. Once the right exposure time has been reached, the lights are switched off and a piezo speaker is buzzed. There’s no mention of they type of bulbs he’s using but they look like compact fluorescent with tin foil beneath as a reflector.

If these are just CFL bulbs, how will the performance compare to a light box based around a UV light source?

[Thanks Jake]

Circuit-bending blog GetLoFi has posted the best tutorial yet on home-made printed circuit boards using the toner transfer method.

We’ve covered homebrew PCB fabrication techniques about a billion times before. What sets this tutorial apart is that it collects many bits of knowledge otherwise scattered all about the web, and then depicts the entire process on video, from initial printing to cut PCB…because reading about it versus seeing it done are two different things entirely. They give a number of immensely useful tips throughout: choice of materials and where to get them, tools and techniques, and dispelling several myths about these methods (for example, they’re adamant about not using acetone to clean toner from the PCB). Well worth the 30 minutes to watch. If that’s too much and you’ve been stuck on just one part of the process, the tutorial is in three segments.

Trimming finished boards on a paper cutter? Who would’ve guessed?

[via Make]

Starting a new robotics project and want to find the perfect servo for the job? It can be a real pain in butt sometimes. This is where ServoDatabase.com comes in. They’re compiling specifications and reviews on servos. We love seeing these databases pop up. Remember the online chip reference? You simply can not have too much reference material.

[via makezine]

Xerox has announced a breakthrough in printable circuits. They’ve developed a conductive ink called “silver bullet” that can be printed on many different types of substrate to create circuits. The key part of the new ink is its lower melting point. Plastic film substrate melts at 150 degrees Celsius but the ink is liquid when ten degrees cooler to avoid damaging the film. This begs the question: how do you then solder components to the circuit?

The benefits of printable circuitry are obvious. Aside from cheaper and easier RFID, disposable circuits like greeting cards, and fabric-based electronics, we’re hoping this will facilitate more environmentally friendly PCB fabrication. That really depends on the ink’s production process and the resilience of the resulting circuitry.

[via Gizmodo]

Above is a video detailing one method for populating a two sided surface mount PCB. We covered using a stencil to apply solder paste for a PCB a few weeks ago. In the comments there was a debate about the virtue of using stencils as well as a question about how two sided boards are populated. This was a good question because reflowing a board twice can cause components on the underside to fall off.

[Wim L's] comment mentions that there are a couple of methods for two sided population. In the video you will see that a stencil is not being used, but instead, paste is applied by a pedal actuated syringe. The paste is applied to the underside of the board first, then a teeny dot of epoxy is added to hold the component in place. Each part is then positioned normally and baked in a reflow oven. This process both reflows the solder, and cures the epoxy. When the board is reflowed a second time, the epoxy holds the bottom components in place as the top solder reaches its melting point.

This method of applying solder paste is slower than using a stencil. But if done correctly, every component can get the amount of solder needed.

Here’s a project from back in 2001 that might be of interest to some of you. It is a guide on how to build your own hot air pencil for SMD soldering.  He is using a super cheap 45W soldering iron from “the shack” combined with a pump type desoldering tool and an aquarium pump. He says it works pretty well, and we don’t see why it shouldn’t. This is a pretty elegant solution. There are also some more recent versions of this mod, but the idea is basically the same.

[thanks Stuart]

A dedicated rolling chest for one’s tools is among the most indulgent yet worthwhile acquisitions. Having everything mobile and organized for quick access improves efficiency and keeps the shop tidy. But holy living crap, have you priced these things? Even a mediocre setup costs more than the gross national product of some small nations!

Here’s a project that tarts up a dresser into a passable tool chest. Using casters, modern drawer pulls and a tidy paint job, they turn a nasty old dresser into something presentable. It’s nowhere near as slick as the commercial units…no ball bearing glides, not chemical resistant, and your macho grease monkey friends will just roll their eyes…but if you’d rather spend your hard-earned money on more and better tools than a pretty box to put them in, this might be just the thing. From across the room, you’d hardly know the difference.

A good tool chest will include several shallow drawers so that all the tools are visible at a glance and not buried in a jumble. If searching for a piece of furniture to re-use, look for something with multiple slim drawers rather than just a few deep ones; a large jewelry chest might work well.

[via Craftynest]

Let’s face it friends, everything is moving toward surface mount components. We’ve seen quite a few features here that cover using stencils to populate boards and using ovens to reflow. [Oleg] has put together a tutorial on the process he uses to populate and reflow his own boards.

[Oleg] is the creator of the USB Isolator and therefore has a need to frequently populate the same board. He’s using an acrylic frame that fits the PCB perfectly to hold it in place so that paste and be applied right up to the edges of the board. He ordered a laser cut Kapton stencil for applying the solder. The paste is squeegeed into the stencil holes, the stencil is removed, and parts are placed with tweezers and a steady hand. For the final step, the boards go into an old toaster oven for reflow.

[Oleg] uses temperature marker on his boards to monitor the progress of the reflow. This marker is basically a crayon that begins to melt at a specific temperature. When the board has cooled, the melted mark can be scraped away or removed with alcohol.

Of course this is only really useful if you have a bunch of high-quality boards to populate. But with the relatively low cost of getting professionally made boards we think the need for this type of assembly process is on the rise.

[Oleg] of Circuits@Home and maker of the USB Isolation Board and the USB Host Shield has a new, two-part hack for his chemistry set. In Part 1 of  this hack, [Oleg] discusses the method he uses to make a stir bar spin and what types of stir bars work the best. Part 2 discusses the motor control code and circuit. Given the ample amount of capability leftover in the Arduino he used, we would like to see this stirrer paired with a heating element to have a complete hotplate/stirrer. What do you think you could do with or to improve this device?

The fantastic Creatrope blog has a great article on quickly assembling animatronic Halloween gags using salvaged electric motors, pvc pipe, and “grid beam” construction.

Grid beam is a prototyping and building medium that’s like a giant hippie Erector set. You can’t buy grid beam, but with a drill press, a jig, and some square stock you can create your own unlimited supply. It’s ideal for “sketching” and temporary constructions like these Halloween props. After use, everything can be dismantled, stored flat, and later reused for the next [Herbie Hancock] music video creative project. Looks like fun!

The article wraps up with some valuable pointers on getting started with grid beam and where to acquire parts.

Reader [Mikey Sklar] told us about a review he wrote covering 3 different models of pocket multimeters. We’re sure that you’ve had the same experiences we have being the go-to-guy or got-to-gal  for all things electrical. For our sort, having a multimeter on hand at all times has become an expectation.

[Mikey] looks at a model from ebay, Harbor Freight, and Radio Shack. Not surprisingly, the ebay offering doesn’t rate too well but does get the job done. We were surprised to read that he picked up the Cen-Tech model for about $10 at Harbor Freight. Although it may no longer be sold there (we haven’t checked) [Mikey] seems pretty happy with it so we’ll be on the lookout during our next tool-buying trip. We’re unfamiliar with the tiny Radio Shack 22-820 but we’ve always been happy with our larger 22-811. The 22-820 allows the probes to be folded up inside of the case cover for a truly pocketable package.

You can never have too many meters at your disposal and we’ll have to keep this article in mind the next time we’re shopping for another. Never used a multimeter before? Take a look at the tutorial [Mikey] linked to over at ladyada.

[bongodrummer] wanted to use a lathe to make some gifts for his family. Instead of buying one, he decided to make one and recycle some parts in the process. More info after the break.

[bongodrummer] scavenged a motor from a washing machine which is a great choice because these motors are capable of generating plenty of torque. To control the speed of the lathe he developed his own pulse width modulation controller. All of the parts were then mounted to some heavy steel plates and an enclosure was built around the belt-driven assembly. In keeping with his recycling goals, the tool rest was fabricated from tubing reclaimed from a junked bicycle frame.

This lathe is not a CNC machine, but judging from the wooden bowl he turned out we’d say this project is a huge success.

In the military, you have to carry tons of stuff. This is something we hear and see all the time. They are always trying to come up with ways to reduce the weight or quantity of the things that you bring into the field. This power generating backpack harnesses the natural up and down motion of your steps to produce power. This could reduce the amount of batteries carried into the field greatly. That’s what they say anyway, how many batteries do soldiers normally carry around? Aside from that point, we think it is pretty cool. We could see using this to keep our cell phone or GPS charged on long hiking and camping trips. You could also build something of your own to work similarly.