Repairing someone else’s design mistakes is much more difficult than starting from scratch. So whenever we come across someone who’s good at this type of trouble-shooting we pay attention. [Jim] had a Sangean HDR-1 in his home. It’s a tabletop HD radio that stopped powering up for some reason. He cracked it open and got to the bottom of the problem.

The first order of business is disassembly, which isn’t too hard with this model. With multimeter in hand he started probing the transformer and found that the contacts for the primary are an open circuit; signaling a problem. There’s no inline fuse for protection, and further study of the secondary winding let him to discover the use of 1N5817 diodes. These are underrated parts for this particular transformer. He replaced them with 1N4003 diodes to bring the device in spec. But there was still the issue of fuse protections. A bit of circuit free-forming allowed him add a fuse and varistor  by soldering the directly to the transformer’s contacts.

Why stop there? While [Jim] had the case open he also swapped out the low-end op-amp and a few electrolytic capacitors to improve the sound quality of the radio. Op-amp replacement seems to be a popular way to improve the sound from HD radios.

[Grenadier] has a thing for the high voltage and, as you can see, he’s found multiple ways to build the icon of HV toys - a Jacob’s Ladder.

The three look similar, but they use different means of generation the voltages necessary to get a spark to jump through the air. The exhibit on the left uses a neon sign transformer, the one in the middle is based on a transformer from an X-ray machine, and the example to the right uses a microwave oven transformer. [Grenadier] discusses the pros and cons of each method, then links to his in-depth posts about working with each one them. There are also videos for all three. We’ve embedded the video for the microwave oven transformer after the break. That version of the Jacob’s Ladder requires some way to start the spark and in the video he’s doing it manually. There is always the option to add a solenoid to do the job but he does mention that you can’t just let it run because that cheap transformer will burn out before long.

If you like what you see here, perhaps you’ll be entertained when he runs HV through some soda cans.

The next time you reach for a cold one, you might want to take a look at the can to ensure that your beer won’t suddenly sprout legs and start skittering across the table.

You might remember [Ron Tajima] from some of his previous creations, including this Roomba-based baby cradle and the PacMan Roomba mod. This time around, he has created a cool little transforming robot that fits inside a beer can.

The robot’s brains are stored just underneath the top of the beer can on a custom-built board. On one side of this board, you will find an mbed controller which is used to manage all of the robot’s functions, and on the other side, four batteries provide all of the device’s power. The robot’s three legs are controlled by six servos, allowing for movement in several different planes. The beer-bot’s movements are controlled with a Wiimote, so we’re assuming he has crammed a Bluetooth module somewhere in there as well.

[Ron] mentions that it moves a bit slowly when standing on end, but we think the robot is pretty awesome as is, and we can’t wait to see what improvements the next version might bring.

Stick around to see a video demonstration of the robot in action.

[Thanks Sascha]

Let’s face it – building robust robots isn’t exactly easy. When designing them, builders often focus on a single method of locomotion in attempts to create a robust, reliable means of transportation. Whether it moves on the ground or in the air, there are always compromises to be made when designing a robot with the ability to travel over variable terrain. Looking to change that, researchers at the Center for Distributed Robotics have recently unveiled a robot that can travel on the ground with ease, then take to the skies in a matter of seconds.

The robot is rolls along the ground on a set of wheels mounted at either end. When it is time to fly, it pushes itself up onto one end before extending its rotors. As you can see in the video below, the transition occurs pretty quickly.

The current prototype is pretty fragile and carries quite the hefty price tag . More robust revisions are already in the works, so expect to see more in the coming months.

[Thanks Sandeep]

Two sparks are better than one, a sentiment that was never more blindingly illustrated than with this three-conductor Jacob’s Ladder. The build centers around three-phase power, which uses a trio of alternating current sources sharing the same frequency, but offset by 1/3 from one another. If we’re reading the schematic correctly, [Jimmy Proton] is using normal mains as a power source, then connecting three transformers and a capacitor to set up the different phases. Two of the transformers, which were pulled from microwave ovens, are wired in antiparallel, with their cores connected to each other. The third transform is connected in series on one leg of the circuit.

The video after the break starts with the satisfying hum of power, only to be outdone by the wild sparks that traverse the air gap between conductors of the ladder. After seeing the first demonstration we kind of expected something to start on fire but it looks like all is well. We’ll probably stick to a less complicated version of Jacob’s Ladder.

[http://www.youtube.com/watch?v=2w54QjtR0nc&w=470]

[Electorials] actually makes working with a flyback inverter sound rather easy. This comes hot on the heals of the huge high voltage collection we saw the other day, but slows way down in the presentation of information. This makes the project very approachable for the newbie, especially considering that the majority of the testing is done with low voltages.

He’s using a flyback transform for this project, which can be pulled from an old CRT monitor. Once you have one in hand, all that’s required to figure out how to use it is a voltometer, a 9V battery, a MOSFET (also salvaged in this case), and miscellaneous components. Once he establishes what each external connection does electronically, [Electorials] builds his circuit on a breadboard, then uses it to create plasma in the bulb above as well as to light up a CCFL.

We know way too little about this subject but hopefully [Bob4analog] helped us learn a little bit more this time around. He’s building his own linear amplifiers on what looks like sheets of MDF. This is an evolving design and the two videos after the break show two different iterations. He’s salvaged several components, like transformers from microwaves, as well as built his own components like the plate choke to the right of the tubes in the image above. In standby, the amp sits at 2800 volts, warming the filament before the unit is switched on.

So what’s he got planned for this? Good question, but it appears that there’s more than enough power to drive a long-range transmitter.

First iteration: two tubes

Second iteration: single tube

[via Make]

[Ladyada] is working on a tutorial series covering power supplies. If you’ve ever built an electronic project you’ve used some type of power supply but we think that most people have no idea how you get from mains power to the DC voltages that most small projects use. So if you want to learn, get started with the first installment which covers AC/DC converters based on a transformer like the one seen above.

These transformers are inside the heavy and hot wall-wart plugs that come with many electronics. We used one along with a breadboard power supply when building the pumpkin LED matrix. They use a pair of coils to step down the voltage to a much smaller level. From there it’s a matter of rectifying the AC into DC power, which she talks about in an easy to follow discussion.

We understand this type of converter quite well but we’re a bit foggy on switch-mode AC/DC converters that don’t use a transformer. They’re much better because you don’t have to build a regulator into the target project like you do with wall-warts. Can’t wait until she gets to that part of the series!

This is a bench power supply with adjustable voltage and current limiting. [Sylvain's] creation can regulate 0-25 volts while sourcing 0-5 amps. Current limiting is a nice feature as it will allow you to test your prototypes to ensure the power regulator you choose will not be over or underpowered.

This supply is really a two-in-one. The case has two separate circuits so that you can have different power rails going at the same time. There is a microcontroller involved, but the ATmega32 doesn’t do anything more than measure the voltage and amperage and drive the graphic LCD screen. Two potentiometers are responsible for setting the voltage and limiting the current.

[Thanks Sargonout]

[Michael] got his hands on a refrigerator that he intended to store beer in but found that it ran constantly. Instead of buying a new thermostat he and his friend [Doug] set out to build an Arduino-based controller for the fridge.

The finished project will switch 240v so they’ve used a transformer to power the logic circuitry and a solid state relay to handle the load switching, with a Dallas 1820 for temperature data. Because the Arduino offers more capabilities than the average thermostat hack they also decided to tap into its potential by adding an Ethernet shield. We see the Arduino as a prototyping device and so do these folks. Once the bugs in their first PCB prototype are worked out the circuit will use the ATmega328 and do away with the Arduino.

[via @littlebirdceo]

It’s hard to believe that in five years we haven’t covered lifters before. This realization was sparked when [Tyler] tipped us off about a lifter project demonstrated at the Kansas City hackerspace called CCCKC.

Lifters, the casual name for ionocraft, fly without combustion or moving parts. We’re not going to tackle the particulars of what makes flight possible, but high voltage is required to feed the phenomenon that provides the lift. One of the first comments when we asked what to do with old CRT monitors was to use them for lifters. The flyback transformer puts out plenty of voltage if you can tap into it without killing yourself (no, seriously, that’s an issue).

This is the method that the CCCKC folks used. Take a peek at the video after the break. If you’re thirsting for more fun with lifters, stop by the Lifter Project.

Want to be visible when cycling at night? [Neon Dean] came up with this possible solution, which he cruised on at Nuit Blanche. Its a bicycle with neon lights mounted on every surface possible. [Dean], who gave a similar treatment to his car, explained how it worked. All of the tubes take their power from a 12VDC battery he carries in a fanny pack. 12V is a far too low voltage to power the tubes, so a step up transformer is used to bring that number way up. [Dean] also decided to install a neon tube on each wheel. In order to deliver power to them, he mounted a rotor on each wheel, with two conductive tracks running close to the edge of each rotor. Two strips of steel act as brushes (in a manner similar to those on slot cars), and deliver the stepped-up power to the tubes. One creative, but perhaps not so bright, idea is [Dean]‘s neon tube helmet.