BPSK On 433 MHz European ISM Band

August 3, 2009 by Steve Watkins 10 Comments

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[WaveRider] is using a type of phase shift keying called BPSK to transmit digital sound and video for remote telemetry. Though a higher signal to noise ratio (SNR) is generally sought after with communications, legal limitations are imposed on total radiated power. To balance the two headed beast, he opted out on frequency shift keying due to binary shift keying’s ability to work with lower SNR. This adds the difficulty of properly reconstructing the digital signal at the receiver. A PLL based carrier regeneration circuit is used to reconstruct the signal. Using the Rabit2000 processor as the host controller on both transmitter and receiver, 96KB/Sec serial data is obtained. On the other side of the spectrum is the Homemade regenerative tube radio.

Diamond Thermal Paste

August 3, 2009 by Gerrit Coetzee 48 Comments

[Jared Bouck] over at InventGeek writes about his experience making his own thermal paste. Diamonds can be up to five times as thermally conductive as silver, the primary ingredient in most popular thermal compounds. He combines 60,000 mesh diamond dust he ordered off eBay with non-conductive silicon grease using a special mixer he constructed to keep down the dust. After some experimentation he achieved a max load temperature of 38 degrees Celsius versus a leading silver paste’s temperature of 57c on the same system.

1wire Attic Cooling

July 31, 2009 by Steve Watkins 28 Comments

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[RagingComputer] built this 1-wire attic cooling fan. He’s using an Ubuntu server loaded with OWFS to control everything. The 1-wire temperature sensor is interfaced using USB while a serial x10 module sends out commands to be received by another x10 module near the fan. Back in the day we had covered a linux home automation project. We also covered HVAC hacks such as the smart attic fan and a 1-Wire HVAC monitoring system.

1-Wire HVAC Monitoring System

July 29, 2009 by Steve Watkins 10 Comments

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The 1-Wire HVAC monitoring system is for residential Geothermal HVAC systems. This project utilizes the so called 1-wire temperature sensor. A single board computer handles the brunt of the work including web accessible trend data. With access to the underling temperatures, the over all system performance may be gauged. Earlier this year we covered a HVAC web enabled monitor that adds an element of control. As the industry adopts modern control architectures, we hope to see more HVAC hacks around.

Propeller-based Terminal

July 25, 2009 by Zach Banks 15 Comments

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[Vince Briel] has created an embedded device based on the Parallax Propeller chip that acts as a serial terminal. It takes input from a standard PS/2 keyboard and outputs color VGA. It also has a second serial port to connect to a PC for debugging or programming. He is selling kits and has the schematics available. The board has a lot of hacking potential and it could easily be made into a video game or a Wikipedia browser.

[via RetroThing]

Custom Flex Sensors

July 25, 2009 by Zach Banks 14 Comments

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Flex sensors, like the ones used in the Nintendo Power Glove, are generally expensive and hard to find. However, [jiovine] demonstrates that they are easy enough to make from spare parts. He sandwiched a strip of plastic from ESD bags between pieces of copper foil, and wrapped the whole thing in heat shrink tubing. The sensor is able to detect bends in either direction, unlike the original power glove sensors. His version had a nominal resistance of about 20k ohms, but by choosing a different resistive layer you could create sensors that are more or less resistive.

Related: 5-cent tilt sensor

Camera Peltier Cooler

July 23, 2009 by Zach Banks 36 Comments

[Gary Honis] has been modifying his Canon Digital Rebel XSi in order to do astrophotography. He previously removed the IR filter and replaced it with a Baader UV-IR cut filter that lets most infrared light through. However, in order to reduce noise in the pictures, he had to cool the camera down. He based the project on a peltier cooler that he salvaged from a powered beverage cooler. He made a small aluminum box and insulated it with styrofoam to hold the camera body. The peltier cooler was then attached on the side. It takes just over an hour to cool the camera down to 40 degrees, but the shots come out a lot clearer.

[thanks adam]