Using the parallel port as a logic sniffer

March 2, 2012 By Leave a Comment

[Fernando] wrote in to share his take on building a logic analyzer. He’s using the parallel port to capture data and feed it to the display software of your choice.

The method depends on a custom kernel which alters the way the parallel port works. The kernel he compiled includes a method of intercepting the signals coming in from the hardware, passing that data to the /dev/parport* as it should, but also sending a copy to /dev/parportsnif*. It also creates a log file which is in the OpenBench Logic Sniffer format for easy use with various display software.

Of course this is easiest to use with a Linux system, but can also be run as a virtual machine under Windows. We’d plan on using a virtual machine within Linux as well since this is a custom kernel and will probably only see occasional use.

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Another take on using 'dead' batteries

February 29, 2012 By Leave a Comment

Here’s another circuit that can be used to squeeze the remaining potential from supposedly dead batteries. Just like the AASaver, we see this as a useful prototyping tool, providing juice for a breadboard even though it’s not reliable enough for long-term use (the batteries are just about through after all).

First off, the image above shows rechargeables instead of alkalines. We don’t recommend this as the circuit has no cutoff feature and the 0.7V input for the boost converter surely is below the recommended low-voltage limit for those cells. But that aside, we like the diminutive board which solders onto the end of a battery pack. It uses an SC120SKTRT which is a variable boost regulator capable of outputting 1.8-5V depending on resistor choices. You can leave the resistors off and it will default to 3.3V, set the output explicitly, or roll in some potentiometers and use your multimeter to tune the output.

This regulator costs more than the MCP1640 used in the AASaver, but it appears to use less passive components making for a smaller footprint. At a total of $3.50 plus the PCB (which will be a snap to etch at home) this is another great option to top off your next parts order.

[Thanks Uwe]

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Squeezing the juice out of some AA batteries

February 27, 2012 By Leave a Comment

[Ray’s] breadboard power supply lets you drain the last traces of power from ‘dead’ AA batteries. Electronics that are powered off of disposable alkaline batteries have a cutoff voltage that usually leaves a fair amount of potential within. Since many municipal recycling programs don’t take the disposables (you’re just supposed to throw them in the trash!) we love the idea of squeezing them for prototyping use.

His design uses just one IC, the MCP1640, along with a handful of passive components. The chip is a boost converter with a startup voltage of just 0.65V, which means the batteries themselves – normally starting life above 1.5V – can be used until they drop to about 0.3V each.

Above you can see the kit he is selling. But it’s an open source project and the circuit is so simple we’re sure you can build your own. Add that boost converter chip to your next parts order for around $0.40.

[Ray] made a nice demo video for the device which you can see embedded after the break.

[Read more…]

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Cheap and easy logic signal generator

February 27, 2012 By Leave a Comment

While function generators or analog signal generators are ubiquitous in their utility, we haven’t seen much of logic function generators on Hack a Day. Luckily, [Dilshan] sent in a really neat 8-channel signal injector that is amazingly simple to build and comes with a great front end for editing patterns from your computer.

The hardware portion of the build is kept to a minimum with a PIC18F chip, USB socket, and header pins as the only major components. This board serves as the hardware output for the Kidogo software. This software provides a very nice interface to generate 5 volt logic signals on eight separate channels that will immensely help exploring your digital world.

With a great interface and very easy to build hardware, we can easily see the Kidogo hardware finding its way onto workbenches around the world. We’re tempted to build our own version using an AVR, but we would hate to ruin such a simple but useful tool.

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Heatless compressed air dryer

February 22, 2012 By Leave a Comment

The pressurized air from a standard air compressor is fine for most uses. But some applications like plasma cutting call for low-humidity air and the hardware available to facilitate this can cost a bundle. [Roland] and his cohorts at TX/RX Labs (a Houston, Texas Hackerspace) just built this air drying system.

It works using a desiccant; a substance that sequesters moister. It’s the stuff in those little packets you find in shoe boxes and the like with a warning that you shouldn’t eat it. The image above shows two chambers which house the desiccant. Only one is used at a time, so that as it’s ability to remove moisture drops, the system can switch over to the other chamber. There’s even an automatic recharging system built in that uses a portion of the dried air to remove the humidity from the unused desiccant chamber.

There’s a functional diagram at the link above. It’s resolution is low enough that the text is almost unreadable but we’ve asked [Roland] if he can repost the image. This seems like a build in which other hackerspaces will be interested.

Filed Under: Hackerspaces, tool hacks Tagged With: , ,

Tired of the Normal Use for Your Toothbrush? Why not an Engraving Tool?

February 21, 2012 By Leave a Comment

Hardware hackers and makers like us may not be well known for our excellent hygiene habits, but after [Dan]’s creation, no one can claim he doesn’t know how to use one! Either out of a total disdain for tooth care, or hopefully, after using one properly for many months, [Dan] decided to turn his electric toothbrush into an engraving tool!

At around $4 and meant for cleaning plaque off teeth, this tool isn’t the most powerful engraver on the block, but is capable of good work on softer material such as acrylic. Be sure to check out the heart that was made with this improvised tool that introduced us to [Dan]’s work.

This is really a clever use of your resources, and the article gives a nice account of how the toothbrush was modified with pictorial directions. Besides it’s use as an engraving tool, this might give someone other ideas for alternate toothbrush uses. For another neat alternate home-item use, why not check out how to repurpose an air freshener as a camera trigger?

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