Body Heat Sensing PC Security System

April 8, 2011 by Mike Nathan 25 Comments

lockifnothot

[Didier Stevens] wrote in to tell us about a little piece of PC security software he put together recently. His application, LockIfNotHot, works in conjunction with your PC as well as an IR temperature sensor in order to lock your computer the moment you step away.

The theory behind the system is pretty simple. Basically, the IR temp sensor monitors when you are at your desk, sensing your presence by the heat your body gives off. As soon as you step away however, it locks the computer since the temperature of the surrounding area immediately drops. It’s pretty simple, but as you can see in the video below, it works quite well.

The software has configurable set points and timeout values, which make it flexible enough to adapt to your specific situation. He happens to use an off-the-shelf IR sensor, but we assume any USB temperature module will do the trick. If you happen to work with sensitive information but often forget to lock your workstation, this is the program for you!

Continue reading to see a quick demonstration of his software in action.

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IR Remote Control Jammer Makes You Lord Of The Livingroom

April 7, 2011 by Mike Szczys 13 Comments

Bring communications jamming technology into your TV viewing experience by building this infrared LED driver circuit. You’re probably familiar with the TV-B-Gone, which let’s you turn off any television at the touch of a button. But what if you actually want to watch the program that’s currently on the screen when the person with remote-in-hand doesn’t? That’s where this little marvel comes in.

[KipKay’s] IR jammer uses a 555 timer to constantly transmit infrared traffic. The signals it’s sending out don’t correspond to commands the TV (or any other IR remote-controlled device) will respond to. But if the light intensity is strong enough, they will interfere with any signals coming in from a remote or even from a TV-B-Gone. [KipKay] wisely hides this circuit inside of another remote control so that the other couch potatoes you are thwarting won’t get wise to what’s happening. If they want to watch something else they’ll have to get up and walk over to the entertainment center to do something about it, and what’s the chance that’s going to happen?

Don’t miss [KipKay’s] infomercial-esque presentation of this gadget after the break.

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Redeye Printer Interface

April 5, 2011 by Kevin Dady 6 Comments

This handy printer interface started out as a request on our very own forums when forum member [victorf] needed some output via thermal printers. He had scored a number of HP82240B thermal printers intended for use with HP calculators, but of course they used the somewhat arcane HP protocol first drafted in the 1960’s and needed some help.

Fellow forum member [wireb] started to look into it, found out it uses a standard 32KHz carrier signal, and started asking questions about its use. Grabbing a pdf of the manual he was able to find out all the details to what the printer was expecting in the form of communications.

After a few weeks, [wireb] was able to make a convenient, logic level serial to HP-IR adapter based around a PIC16F1824 who’s firmware supports 9600 8N1 or 2400 8N1 speeds, ASCII text, and the printer’s “advanced” graphical modes via escape sequences.

If you have not checked out our forums yet we suggest you do!

Gun Turret Built Into A Cake Box

April 3, 2011 by Mike Szczys 17 Comments

Couch potatoes have a new line of defense thanks to this remote-controlled turret. The gun itself is a hacked down airsoft model. The mount started with a servo motor in the center of a plastic cake box. A thin strip of plywood was added, along with a couple of sliding furniture feet to stabilize the platform as it rotates. A second servo mounts to that platform, which allows the trajectory of the projectile to be adjusted up or down. A PIC 18F4520 controls both of the motors, as well as the firing of the airsoft module, all while listening for commands from an IR receiver. Just adjust the firmware to match an unused device on your universal remote and the power to annoy your roommates will be at the tips of your fingers.

You can see an overview of the build process, as well as a demonstration of the final project in the video after the break. The page linked at the top has a very detailed build log but some of the ‘next’ buttons on that page don’t work for us. Luckily you’ll see a table of contents in the right column which lets you navigate around these bad links.

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Control Your Home Theater From Anywhere In The World

March 14, 2011 by Mike Nathan 21 Comments

ether_ir

Using IR repeaters for larger home theater setups is not uncommon, but they usually are quite simple. A series of IR receivers are placed throughout a home, all wired to repeat the signals in a central closet where all of the AV equipment is located. [Bill] constructed a solution that works much like a standard IR repeater setup, however his requires no receivers, and it can be used anywhere in the world, provided you have Internet access.

His project, called Ether IR, is an Internet-enabled IR repeater. It consists of an Ethernet-connected module with an IR LED mounted on it, capable of controlling your AV equipment. The board is hooked up to your LAN, and relays commands to your home theater via a simple web page. The equipment can then be controlled from any Internet-connected device, such as a mobile phone or tablet PC.

The entire project is open-source, so [Bill] has included schematics, instructions, and a bill of materials so that you can construct your own. The only issue at this point is the software portion of the project. The software is free, but the distribution method is in question – once things are sorted out, he will ensure that you can obtain the software for your Either-IR from him or directly from the Ethernet chip’s manufacturer.

Arduino Thermo-cam

March 9, 2011 by Kevin Dady 31 Comments

[Maxbot] wanted a inferared themo-cam that he could use to scan an area and display the results on his computer, the result is this Cheap-Thermocam. This little device is a inexpensive thermal sensor mounted on a pair of servo’s for XY scanning, custom java software and an Arudino to mate the two.

The sanner does a limited but still useful resolution of 42×32 pixels. To help out with smoothness of the colors, every other line of the finished product is interpolated against its neighbors. It takes the device about two minutes to measure each of the 1344 points, but what it lacks in speed it more than makes up for in cost, boasting around 100$ build cost, and ease of construction.

While exact details of what parts you need and how to hook everything up is lacking at this moment, there is a page in the works that will let you know all the good details “soon”, though if you are inspired to replicate one of these nifty devices it seems the most difficult part would be tapping into the sensor’s electronics and the custom software.

Cheap, hacky, and even comes with its own roll of duct tape. We have a short video for you after the break.

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38 KHz IR Communications Tutorial

February 16, 2011 by Mike Szczys 14 Comments

Learning about how infrared remote controls work is a great way to expand your electronics knowledge. That’s because this technology is invisible to our eye, and happening faster than we can comprehend without help from test equipment. This tutorial over at Pyroelectro talks about the theory behind how the data is transferred and shows you how to build a couple of circuits to experiment with and communicate through infrared light transmissions.

Instead of going with an IR receiver module you’ll build your own using a photo-transistor and an operational amplifier. The Opamp is used to amplify and invert the signal picked up from the IR transmission of a common home entertainment remote control. From there the digital signal is read by a PIC 18F452 microcontroller for processing. But if you want to use a different microcontroller there’s still more than enough usable information to get you across the finish line.