[Dino] Tells Us About Transistor-based On/off Switches

August 22, 2011 by Mike Nathan 12 Comments

hackaweek_transistor_onoffswitch

You know them, you love them, you take them for granted – they are single push button on/off switches. As [Dino] explains in the most recent episode of his Hack a Week series, they are typically implemented in the form of IC logic switches nowadays, but it wasn’t always that way. When they first came on to the scene in the 70’s, the single button soft switches were built using a set of transistors and a capacitor to get the job done, so [Dino] decided to research push on/push off transistor switches a bit and build his own.

After reading through a short tutorial, he was ready to go. As he explains in the video, the operation of the switch is fairly simple, though he did run into some odd issues when he prototyped the switch on a piece of breadboard. He’s looking for someone to explain why the unstable circuit suddenly performs better with the addition of a small capacitor between the battery’s positive lead and the circuit’s output, so if you have some insight, be sure to speak up in the comments.

In the meantime, check out [Dino’s] exploration of push on/push off switches below.

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Polarized Art Fixture Made From A Busted Laptop Screen

August 22, 2011 by Mike Nathan 21 Comments

[Pedro] had a busted laptop LCD screen on his hands, but rather than throw it out, he brainstormed what he could possibly do with what would typically be considered a worthless item. He decided to make a simple art installation using the scrapped part, so he gathered a few other supplies and got to work.

The first thing he did was pull the LCD screen from the laptop, separating the front panel from the backlight panel. He drained the liquid crystal fluid from the display, and set it inside a picture frame in place of the glass. He added spacers around the edge of the frame so that the backlight could be mounted several inches behind the LCD panel.

[Pedro] then found a few polystyrene and polycarbonate plastic items from around the house, and placed them inside the frame. As you can see in the picture above, the polarizing filter built into the LCD screen makes for some pretty cool effects.

While you could debate for hours over exactly what is art, there’s no denying that his PolFrame looks cool and is a great way to save electronics from the scrap heap. We just want to know what he did with the LC fluid he drained from the screen!

Video: Shocking [Jack] Into Submission With High Voltage

August 22, 2011 by Jack Buffington 59 Comments

Hackaday headquarters has recently been overrun by techno-groupies hanging around outside so we decided to take some measures to discourage that. A word of warning though, if last week’s video ruffled your feathers then you probably shouldn’t watch this one. In this video [Jack] shows you how to create a stun glove using a disposable camera and some leather spikes. To prove that it really works, he intentionally takes a jolt from it courtesy of Hackaday’s security chief [Vlad].

Check out the video after the break.
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One-man SMD Assembly Line Shares A Lot Of Tips About Doing It Right

August 21, 2011 by Mike Szczys 33 Comments

Need to use that antiquated hardware that can only be connected via a parallel port? It might take you some time to find a computer that still has one of those, or you could try out this USB to Parallel port converter. It’s not limited to working with printers, as the driver builds a virtual parallel port that you should be able to use for any purpose. But what we’re really interested in here isn’t the converter itself, but the build process. [Henrik Haftmann] posted a three-part series of videos on the assembly process, which you can watch after the break.

The build is mostly surface mount soldering with just a handful of components that need to be hand soldered. The first of his videos shows him stenciling solder paste onto the boards. From what we can see it looks like he built a nice jig for this using scrap pieces of copper-clad which match the thickness of the PCB, and hold it and the stencil securely in place. There’s a bunch of other tips you can glean from the videos, like the image seen above. It’s a clamp that holds the PCB and USB jack together while they are soldered.

If you’re ever thinking of assembling a bunch of boards you should set aside thirty minutes to watch them all.

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High Voltage: Using Enclosed Relays For HV Switching

August 19, 2011 by Mike Szczys 21 Comments

After seeing many projects that use microcontrollers to switch mains voltages [Rob Miles] decided to share his preferred method. The shots you see above are an enclosed relay, part number RIBTU1C manufactured by Functional Devices Inc.

This in itself is not the full control scheme that he uses, but it takes care of the bulk of the hardware. He uses a triggering circuit based on a 555 timer (PDF). [Rob] mentioned that if you shop around, you can get the relay, 555 timer, and other components for under $15. This is a great solution for the money when you consider that you get an enclosure meant for handling high voltage and a nice terminal block to which you can connect the mains wiring. The relay itself can be triggered by a 9V battery via the transistor in the control circuit.

Notice the protoboard in the image above. There’s plenty of room for your driver circuit to rest inside the box, protected by that barrier from the HV circuitry. Check out the rest of the images he sent us after the break.

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Robotic Artist Listens To Your Criticism

August 18, 2011 by Brian Benchoff 8 Comments

[Ben Grosser] built an interactive painting robot that’s pretty far removed from the LED and Arduino builds we usually see. The robot is adapted from one of the many CNC routers we’ve featured over the years. The control system is written in Python and uses genetic algorithms and a microphone to decide what to paint next.

Robot artists have been around for decades now. When [Harold Cohen] exhibited his robotic artist AARON, gallery patrons lined up to watch a robot paint. The paintings were originally just a monochrome line drawing that was later colored in by [Cohen]. [Ben] made his robot paint directly onto canvas with oil paints, so there’s no question of what the computer intends the final product to be.

[Ben] came up with a really neat build, but we’re wondering about having this robot artist on display inside a cavernous exhibition hall. Surely the echos from the servos and stepper motors would be picked up by the mic and interpreted by the painting algorithm. Barring some control systems, it would probably be the robot’s commentary on its own decent into madness.

Check out a video of the robot in action after the break, followed by a violin/robot duet the shows how the audio is interpreted.

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High Voltage Plasma Lamp Is Also Tasteful Steampunk

August 18, 2011 by Brian Benchoff 21 Comments

Instructables user [Admiral Aaron Ravensdale] just finished a high voltage plasma bulb build that makes creative use of off-the-shelf parts. As a self-described steampunk, [Adm. Ravensdale] also earned some cred by included working gears in his build.

The heart of the build is a “flicker flame” candle light bulb. These light bulbs have two flame-shaped plates inside the bulb to act as electrodes. Instead of the Argon that normally fills an incandescent light bulb, the candle bulb is filled with Neon. When excited, Argon gives off a rather unnatural purple glow – not very convincing for a simulated candle and certainly not steampunk. The Neon in the flickering candle bulb gives off a brilliant orange, perfect for simulating a flame and will surely impress the duchess during afternoon tea.

After the right plasma bulb was found, [The Admiral] scavenged the rest of the high voltage electronics from disposable cameras. Attaching three electrodes to a brass gear, the entire mechanism was made to spin using parts from an old clock and a CD drive motor. We’re always impressed with the scavenging abilities of steampunkers – we’d still be waiting for our gears to arrive if we attempted this. Check out the video of this really cool and very inexpensive plasma bulb after the break.

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