Light Bulb, Diode, And Capacitor Step Mains Down To 12V DC

October 21, 2011 by Mike Szczys 64 Comments

[Todd Harrison] needed a way to run a 12 volt PC fan from mains voltage. Well, we think he really just needed something to keep him occupied on a Sunday, but that’s beside the point. He shows us how he did this in a non-traditional way by using the resistive load of an incandescent light bulb, a diode, and a capacitor to convert voltage to what he needed. You can read his article, or settle in for the thirty-five minute video after the break where he explains his circuit.

The concept here is fairly simple. The diode acts as a half-wave rectifier by preventing the negative trough of the alternating current from passing into his circuit. The positive peaks of the electricity travel through the light bulb, which knocks down the voltage to a usable level. Finally, the capacitor fills the gaps where the negative current of the AC used to be, providing direct current to the fan. It’s easy to follow but the we needed some help with the math for calculating the correct lightbulb to use to get our desired output current.

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Illogical Voltage Double Uses Logic

October 21, 2011 by Mike Szczys 5 Comments

[Jonathan Thomson] just finished writing up his entry for the 7400 logic contest. It’s a voltage doubler that uses a 74HC14 logic chip. Because this is not at all what the chip was meant for–and he’s a sucker for puns–he’s calling it the Illogical Dickson Doubler.

What he’s got here is basically a charge pump built from a set of diodes and capacitors. On the breadboard you see two chips, one is used as a clock signal generator for the other which is acting as part of the charge pump. We’ve seen a string of hacks that ~~mis~~use the protection diodes on the inputs of logic chips. In fact, [Jonathan’s] setup uses the same back power concept that barebones PIC RFID tag did. You may remember in that project the chip was being powered from one of the I/O pins, with the VCC pin not connected to anything.

We’ve embedded a video after the break with shows some voltage measurements, as well as an LED being powered from the doubling circuit.

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RAM Upgrade For WRT300N Router

October 20, 2011 by Mike Szczys 1 Comment

[Heli] had a WRT300N wireless router sitting around collecting dust. He decided to squeeze at bit more entertainment value out of it by seeing if he could pull off a RAM upgrade. He managed to double the router’s RAM and posted a walk through (translated) to help you do the same.

Swapping out surface mount RAM chips isn’t the easiest thing in the world and you must wondering what prompted this. It seems he wanted to run the LuCI package on the router but it was slow (or even incapable) of booting with the stock hardware’s 16 Mb. He first sourced some pin-compatible replacement chips from an old Pentium III computer. While his soldering iron was hot, he also wired up a JTAG header, which connects via the red wires just visible to the left. When he first fired up the unit he was happy that it was able to boot, but it still only detected 16 Mb.

It turns out you’re going to need to roll your own kernel to get it to take advantage of the upgrade. Source code for OpenWRT is easy to find and there’s plenty of guides for compiling it. If you try this, make sure to read [Heli’s] post carefully as he’s got some important configuration information that will help you to avoid bricking your router.

Analog Test Interface For Your Computer

October 20, 2011 by Mike Szczys 6 Comments

Wanting to test the response curves on some analog parts, [Don Sauer] devised a way of using simple tools to graph analog tests on a computer. Here you can see the results of testing NPN, PNP, NMOS and PMOS transistors, but modifying the input circuitry would let you test just about anything you want.

[Don] is using an Arduino as the hardware interface. He needed some additional parts, like an op-amp and some passives. Instead of building this on a breadboard, he printed the circuit out on a piece of cardboard, hot glued the components in place, then wired them up. This will let him reuse the interface in the future, but is quicker than designing and etching a PCB.

He uses a Processing sketch to capture the test data streaming in from the Arduino. Once recorded, he uses SciLab to create the graphs. He also covers a method of sifting through the data using Octave, another open source program that feels somewhat like MATLAB.

A CD Changer Made Of Wood

October 18, 2011 by Jeremy Cook 15 Comments

Although this is by no means a new hack – it was made circe 2002 – this wooden CD changer is an interesting piece of machinery. The whole thing is a simple pick-and-place device. The gripper is brilliant in it’s simplicity, using only a rubber band, wood, and a solenoid. It grips the CD by the middle hole, picks it up, and the assembly then travels to the CD tray or the stack. Everything works with DC motors and string, and several micro-switches make sure everything is picked up and dropped in the correct position.

Although we may think this is a pretty cool device, [Matthias] is quite humble about his machine’s abilities. In his estimation, although one could probably duplicate 12 CDs with relative ease, if you really wanted to duplicate a large number, it’d be best to buy one. Maybe he works in manufacturing.

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Easy To Use Automatic QR Code Generator

October 16, 2011 by Mike Nathan 20 Comments

custom_qr_code_generator

Love them or hate them, plenty of people around the world use QR codes on a daily basis. Since he thinks they’re pretty great, Hackaday reader [falldeaf] thought it would be cool to put together an automatic QR code generator to be used on web sites.

Inspired by the custom QR logo embedding work done by our own [Brian Benchoff], his dynamic QR code generator allows you to do the same thing, but with far less work. The code requires that you have PHP and the GD library installed on your server, but other than that his code does the rest.

All you need to do is call up the page and pass along a URL, optional caption text, optional image overlay (to add your logo to the center of the code), as well as an optional hash code for tracking traffic sources. The page spits out a png image that can be used on its own, or embedded in a blog, which is what [falldeaf] plans on using it for.

If QR codes are your thing, be sure to grab a copy of his code, it will certainly be a handy tool to have around.

Contest Entry Roulette

October 14, 2011 by Mike Szczys 17 Comments

Over 150 projects made from scrap parts (translated) have been posted for your viewing pleasure. They make up the entries in the “Make fast the scrap” project from c’t magazine. We already looked in on a toilet paper printer, but there’s a ton of other fun stuff to look at as well.

Every time you load the link at the top, the page picks a different set of entries to display. You can click through all the pages, or reload to play a little project roulette. The image above shows three that caught our eye. To the upper right is a lighbulb-man riding an old computer mouse reverse-cowgirl style. Quirky, but anyone who has access to an electroplating setup can get away with making simple objects like this into awesome desktop sculptures.

Moving clockwise we have a tiny USB drive mated with an old vacuum tube. The machine translation is a bit rough, but it looks like the LED from the thumb drive gives the tube a bit of a red glow. We just think it’s interesting to carry around a vacuum tube with you.

The final banner image shows a gyroscope for a camcorder. This is an awesome setup, which you can see in action after the break. A pair of broken hard drives provide motion stabilization for a camera. The entire assembly has a handle on the top with a universal joint. When the drives are spinning, the platform holds very still, even if the operator is swinging the unit around wildly.

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