Author: Mike Szczys

6403 Articles

Beefy Battery Backup Still Running After A Decade

October 8, 2010 by 39 Comments

In 1997 [Michael Butkus Jr.] found an uninterruptible power supply in the dumpster. The batteries were shot, but he needed a backup to keep his pellet stove running for heat, drive the exhaust fan to keep the smoke out of the house, and power his computer and other electronics. After a bit of head scratching he decided to beef up the UPS using deep-cycle batteries.

He actually built two of these. One is smaller, and similar to what we’ve seen before. The other is larger and uses four batteries, two pairs in parallel which are then connected in series. He’s careful to use heavy gauge wiring and 50 amp fuses for each battery, both of which will protect against the risk of fire. One thing we found interesting is that the batteries are stored in the basement, directly below the UPS which is connected via a short run of 12 gauge home electrical wire.

We were happy to see that he’s done updates at the top of his post over the years. He lost a few batteries due to neglectfully letting the water levels drop too much. He did switch over to sealed automotive batteries sometime in 2004 or 2005. Looks like things have been going strong ever since.

[Thanks Spencer]

Reddit Hacking For Votes And Profit

October 8, 2010 by 36 Comments

Looks like someone figured out how to game the Reddit system. This probably has been done before, but as far as we know nobody’s actually shared the methods in detail. [Esrun] wrote some scripts that allow him to register multiple accounts and use them to up-vote stories.

The hack goes something like this. A script registers a group of accounts. Each uses a different IP and the only part that requires intervention is typing in the Captcha. This doesn’t take long. You can see the script interface above as well as a demonstration video after the break.

Once the accounts have been acquired a story is submitted and the new accounts vote on it. They’re not all up-votes though, as having both up and down votes puts the article into the controversial section of Reddit (which is desirable), and doesn’t rouse as much suspicion from the moderators. He ran a few tests that he shares and it seems that as long as the article is interesting, this can be quite successful.

Great, more spam with our social media please.

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Add Supercaps To Your Exercise Routine

October 8, 2010 by 26 Comments

Many exercise machines generate electricity as you pedal or climb in order to run the on-board electronics. Unfortunately if you stop or even slow down too much the juice will die and your exercise program will reset. Wanting to improve on this gotcha, [Mike] cracked open his exercise bike and added some super capacitors.

On the circuit board he found an ATmega128 was in charge of the user interface. He probed the board a little bit and couldn’t find how it was connected to the power regulators. After some additional snooping he found it has its own SOIC regulator separate from the ones that run the display and peripherals. He takes us through the calculations he made before choosing his parts. What he ended up with is a set of three supercaps in series that add about two minutes of juice before the levels drop and the chip resets. The design of the board helped a lot as the high-load electronics (like the LCD screen) are on a separate power bus than the processor.

Game Boy Printer USB Cable And Software

October 8, 2010 by 19 Comments

[Furrtek] hooked up his Game Boy printer for use with a PC (translated). The two-part hack started with a cable to attach the device via USB. A Nokia interface cable was used as a base to translate the USB signals into serial, and an ATtiny45 microcontroller added to talk to the printer. He did a great job of free-forming the circuit alterations and fitting it back into the plastic USB plug housing.The next step was to write some software. Using VB6 he coded an application that loads in an image, scales it to fit, and allows you to adjust the contrast that the thermal printer produces. For testing purposes he’s reusing old receipts. See it in action after the break.

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Bench Supply With Current Limiting

October 8, 2010 by 14 Comments

This is a bench power supply with adjustable voltage and current limiting. [Sylvain’s] creation can regulate 0-25 volts while sourcing 0-5 amps. Current limiting is a nice feature as it will allow you to test your prototypes to ensure the power regulator you choose will not be over or underpowered.

This supply is really a two-in-one. The case has two separate circuits so that you can have different power rails going at the same time. There is a microcontroller involved, but the ATmega32 doesn’t do anything more than measure the voltage and amperage and drive the graphic LCD screen. Two potentiometers are responsible for setting the voltage and limiting the current.

[Thanks Sargonout]

Playing Piano With Optical Sensors

October 7, 2010 by 16 Comments

[Sebastian] is trying to improve the responsiveness of an electric keyboard. He was unsatisfied with the lack of adequate sensitivity to keystroke. The first step in his process was to measure how fast the quickest keystroke actually is. By setting up an LED and phototransistor and taking some measurements he found that sampling at 1 kHz would be more than adequate.

With initial testing complete he ordered some CNY70 transmissive/reflective light sensors that can be place below the keys. He measures the sensor with the ADC on an ATmega16 microcontroller. Running at 16 MHz he can sample each of the eight analog-to-digital converter channels at 1202 Hz. After doing a bunch of math he put together some lookup tables that are used to translate the ADC data into midi signals. We’ve embedded a video of one sensor controlling the midi program PianoTeq. [Sebastian] also sent us a schematic of one node in the sensor network (see it after the break).

When everything is said and done he plans to use eleven ATmega16 microcontrollers to address the 88 keys, with an additional microcontroller to act as the master using a two-wire interface for communications.

Update: [Sebastian] put up a webpage with a fairly verbose description. Reading it straight from the source really clears up a lot of questions.

 

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An Interesting Take On WEP Cracking

October 7, 2010 by 19 Comments

[Ben Kurtz] is doing a little WEP cracking but in a bit of a different way than we’re used to. WEP cracking makes us think of war driving; driving around with your laptop open, looking for WiFi access points, and stopping to run some software when you find them. [Ben’s] way is similar but different in one key way, he’s using an iPhone as the frontend.

This started as a way to find a use for some leftover equipment. He threw together a Linux box and loaded up Aircrack-ng, the software we often see used in penetration testing. To remove himself from shady-looking activities in public he coded a web interface using the Python package Turbogears. It uses screen, a program often used with SSH to run services concurrently in different terminals, with the option to disconnect without stopping the processes. Now it’s just a matter of parking the hardware near an AP, and doing the work in a browser on your mobile device. You can check out the script he wrote, as well as installation instructions, in his post linked above.

[Thanks Tech B.]

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