Power Supplies And Transformers; A Learning Experience

[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!

Halloween Props: Borg Costume

The Halloween hacks are rolling in late this year, but we’re delighted to see that [DJ Sures] finished his borg costume in time. It is made up of a hodge-podge of items from different cultures… oh wait, so are the borg. These include a set of hockey pads spray painted black with just a light misting of silver to give them some depth. After taking the image above (which mostly shows off his makeup) [DJ Sures] added an LCD screen to the chest plate and lighted electronics throughout. See for yourself after the break.

If you liked this you might take a look at his singing spark plug.

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Halloween Props: Talking Skeleton In Reaper Robes

Here’s a great way to guard your front door on Halloween. [Sam Seide] built a motion controlled talking skeleton. The electronics are fairly straight forward, consisting of an Arduino, WAV shield, PIR motion sensor, servo motor for the jaw, and a couple of red LEDs for the eyes. But [Sam] did some really neat things in the design of the skeleton itself. As we saw with the puking pirate, he built the body out of PVC so that he can take it apart for easy storage. Under the reaper robe you’ll find a set of powered computer speakers that connect to the WAV shield. The servo motor is mounted in the skull and moves the jaw using a small wire arm. Since the whole thing is a bit flexible (thanks to the PVC), the torque of the motor causes the skeleton to move around, adding a touch of life. Don’t miss the well-made video walkthrough after the break.

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Smallest Gaming Console Ever. EVER!

That’s it… the controller and the video game system all in one. This is the standalone version of [Rossum’s] RBox. We looked in on the prototype in June but that was using a bulky development board. You can see the CR1632 button battery, which powers the device for about four hours, sandwiched in between the joystick and the mainboard. Exiting the image on the right are cables used to connect mono-audio and video to a TV via RCA connectors. There’s no port for interchangeable cartridges which means that all game data must be programmed into the ARM Cortex M0 processors. See [Rossum’s] demo video after the break.

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70 LED Matrix In A Jack-o-lantern

What takes eight hours to solder and uses more shrink tubing that you thought imaginable? An LED matrix installed in a real pumpkin. When I mentioned that we’d like the LED pumpkin in last Friday’s post scaled up to a full LED matrix I had no idea it would be me doing the work. But [Caleb] and I thought it might be just the thing to present for the hacker’s favorite holiday.

Installed in the autumn vegetable is a marquee made from a 5×14 matrix of light emitting diodes. I spaced them by printing out a grid on the computer, taping it to the pumpkin, and drilling 70 holes in the front of the thing. The real trouble came when inserting all of the LEDs from the inside; each of them has four wires soldered to it, creating a net of black wiring. Above you can see it turned out great. This is a shot of it scrolling the message HAPPY HALLOWEEN.

Join us after the break for video of this prop. But we’re not just sharing the finished product. I’ll take you through the build process. Along the way you’ll learn the design considerations that go into an LED matrix and how you can use these techniques to build your own in any size and configuration you desire.

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Robot Gripper Uses Coffee To Pick Up Anything

Picking up a raw egg is not something we’d think a robot gripper would be good at. But this model uses a bulbous tip instead of claw, which makes crushing the object less of a concern.

That tip is kind of like a balloon. It is stretched full with coffee grounds but air can also be pumped in and sucked out. When it comes time to grip an object, a bit of air is pumped in and the bulb is pressed down on its target. Once in place all of the air is sucked out, locking the coffee grounds around the object. Take a look after the break to see just how many things can be gripped with this technique.

Now the real question, can it bring me a beer?

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Security Flaw Bypasses IPhone Lock Screen

It looks like the iPhone lock screen provides just a marginal level of protection. [Jordand321] discovered a key combination that opens the contact app on a locked iPhone. Just tap the emergency call button, enter the pound sign three times (###), then tap call and immediately tap the lock key on the top of the phone. If this is confusing just look at the video after the break to see how it’s done.

You don’t get access to everything on the device. But this does give an attacker access to all of your contact data and allows that person to make any calls they desire.

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