Repurposing Server PSU For Your Charging Needs

July 17, 2012 by Mike Szczys 21 Comments

That grey box at the top of the photo is a modular power supply unit for a rack-mounted server system. [Sebastian] decided to repurpose it as a charging source for his RC batteries. He chose this HP DPS-600PB because of its power rating, efficiency, and you can get them at a reasonable price.

This is an active power factor corrected (APFC) PSU, which he says draws 40% less current than the non-APFC variety. Since he sometimes charges batteries in the field from a generator this is a big plus. But a bit of modification is necessary before it can be used as a source.

Since this is a rack device it has a set of connectors on the back. For power there are spade connectors which mate with a fin on the rack. He soldered positive and negative leads between the spades to interface with the battery chargers. The PSU won’t fire up if it’s not in the rack, so some jumper wires also need to be added connecting three of the interface pins.

With his modding all worked out he went on to use two PSUs for a 24V source, housing them to a nice carrying case while at it.

Dealing With The Horrors Of PDFs By Binding Your Own Books

July 16, 2012 by Brian Benchoff 66 Comments

Looking at a few PDFs of data sheets, journal articles, or even complete books can be a pain. Not only do you have to deal with the torment of a PDF reader (we’re looking at you, Adobe), but a purely electronic document misses the beautiful tactile interface available in dead tree format. [samimy] put together an amazingly professional video showing us how to turn our convenient yet unwieldy PDFs into paperback books, perfect for a very accessible off-line reference.

[samimy]’s build is basically a few pieces of wood and C clamps designed to compress the printed PDF together. After drilling a few holes along the spine, he stitches the pages together with very strong thread and applies a little glue to the spine. After removing the pages from the press, [samimy] applied a piece of tape to the spine and had a very nice looking paperback book.

While [samimy] is using his binding jig for data sheets, we see no reason why a more prodigious tome couldn’t be created with his rig. A few pages of marbled paper and a leather cover would result in a beautiful and functional work of art that will be around long after you’re gone.

Android Oscilloscope Built From Parts Just Lying Around

July 14, 2012 by Brian Benchoff 36 Comments

So you need to debug a circuit and you don’t have an oscilloscope. That’s not a problem thanks to [retronics] $0 Android oscilloscope, made with parts he just happened to have lying around.

The heart of every modern oscilloscope is the ADC – the chip that takes analog input and outputs a digital signal. Every Android device has one of these converters connected to the microphone port. All [retronics] needed to do was solder up a 3mm headphone jack, wire in a few resistors, and attach a pair of alligator clips. After installing an oscilloscope app, [retronics] had a half decent ‘scope.

Yes, this is truly a poor man’s oscilloscope, and [retronics] probably won’t be debugging high frequency RF circuits with his Android microphone jack anytime soon. Low frequency stuff such as audio is where this ‘scope really excels; even more so if a small preamp is thrown into the mix.

You can check out [retronics]’ build after the break. Sure, it’s not something for precise and calibrated measurement, but sometimes you only need a tool that will do the job.

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Hacking A Parallel Port Flash Memory Programmer

July 14, 2012 by Mike Szczys 12 Comments

[Pulko Mandy] doesn’t use his flash ROM programmer very often, but he does use it. When he tried to get support for a new chip and the manufacturer suggested he just buy a newer version he decided to hack the programmer and it’s software instead.

This device connects to the parallel port and was intended for use with MS-DOS systems (no wonder there’s no longer support from the company). The board uses logic chips to add read and write function. So the first step was to analyze how they connect together and come up with a set of commands. While at it he also made some changes to the board to bring the voltage more in spec and ensure the logic levels on the parallel port met the correct voltages.

His plan was to use the board with a Linux system so the parallel port interface can stay. He used what he learned from the hardware inspection to write his own interface in C++. It works with a chip he was able to use under the MS-DOS software, but he hasn’t gotten it to work with the chip that sparked this adventure. If you’re familiar with how the AT29C040A works please consider lending a hand.

Sorting Resistors With Speech Recognition

July 13, 2012 by Brian Benchoff 21 Comments

If you’ve ever had to organize a bunch of resistors, you’ll know why [Anthony] created EESpeak. It’s a voice-controlled component look up tool that calculates a component value by listening to you read out color code bands.

In his demo video of EESpeak, [Anthony] reads off the color bands of several resistors whilst the program dutifully calculates and displays the value. [Anthony] also included support for calculating the value of capacitors and inductors by speaking the color bands, as well as EIA-96 codes for SMD parts.

In addition to taking speech input and flashing a component value on the screen, EESpeak also has a text-to-speech function that will tell you what a component without ever having to look at your monitor.

Even though the text-to-speech function seems a little cumbersome – it takes much longer for a computer to speak a value than to display it on the screen – using voice recognition to calculate component values is an awesome idea. With an extremely limited vocabulary the computer has to understand, the error rate of EESpeak is probably very low.

You can check out [Anthony]’s demo video after the break, and of course download the app on his blog.

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Logic Analyzer Add-on For The MSP430 Launchpad

July 9, 2012 by Mike Szczys 12 Comments

Here’s a 6-channel logic analyzer shield for the MSP430 Launchpad. It manages an eyebrow-raising 16 million samples per second. The prototype seen above is made on a hunk of protoboard with point-to-point soldering. [oPossum] did lay out a PCB — which is just 50mmx50mm — but has not had any produced quite yet.

He calls it the LogicBoost, and based it on the the LogicShrimp design. The sextuplet of 8-pin chips are all SPI RAM. These are responsible for storing the samples, with a 74HC573 latch routing the traffic. The MSP430 chip provides the SPI clock, and the Launchpad’s virtual com port can be used to push the data to a computer for graphing. That’s a bit slow so [oPossum] also included an optional header for an FTDI board that will do a faster job. The sample rate can be adjusted by tweaking the internal oscillator setting of the chip; there’s plenty to choose from so it will work for just about any purpose (as long as you don’t surpass the 16 Msps speed limit).

[via Dangerous Prototypes]

Proximity Switch For Your Mains Devices

July 8, 2012 by Mike Szczys 17 Comments

[Ivan’s] friend built a proximity sensor to switch his LED bench lighting off every time he walked away. The idea is pretty neat, so [Ivan] decided to implement it for mains devices by making this proximity switched outlet box.

A Sharp GP2D12 infrared distance sensor is the key to the system. It has an emitter and receiver that combine to give distance feedback base on how much of the light is reflected back to the detector. This is presented as a voltage curve which is monitored by an ATtiny85 (running the Arduino bootloader). It is small enough to fit inside the outlet box along with a tiny transformer and linear regulator to power to logic circuitry. The mains are switched with a relay using an NPN transistor to protect the chip’s I/O pins.

Check out the video after the break to see this in action. It should be a snap to add a count-down timer that gives you a bit more freedom to move around the workshop. With that in place this is a fantastic alternative to some other auto-shutoff techniques for your bench outlets.

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