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.

1-Wire HVAC Monitoring System

July 29, 2009 by Steve Watkins 10 Comments

1-wire hvac control

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.

Music Visualizer (oscilloscope)

July 29, 2009 by Steve Watkins 21 Comments

musicscopetv

The Music visualizer is actually a second build based on an earlier design[Thanks Roger]. The build was influenced by Zyra’s How to make an oscilloscope out of a television. The hack is quite simple, patch the output of an amplifier into the vertical deflection coils of the CRT. This is a good use for that old TV you may have laying around but don’t want to recycle it just yet. While on the subject we had covered the Mac SE/30 audio visualizer in 2006. For those looking for something a little more hard core, here is a bit about Homemade cathode ray tubes.

Perpetual Ball Roller

July 29, 2009 by Caleb Kraft 45 Comments

[youtube=http://www.youtube.com/watch?v=Te9X4VRj8dU]

This interesting little sculpture caught our eye. Called the Perpetual Ball Roller, it simply rolls a ball on a track. It has both manual and automatic modes with variations in the automatic mode to keep it amusing. This is very elegant, and would be fun to have sitting around to play with. The only problem is the noise. The servo that he is using is quite loud. What could he do to make it function silently?

[via Instructables]

Stereo Guitar

July 27, 2009 by Caleb Kraft 39 Comments

stereo_guitar

[Megatronix] wrote in to show us this pretty crazy guitar mod. He has re wired the pickups to make the guitar a “Stereo Guitar“. Generally, the two pickup locations on a guitar are there to provide tonal variation. You can adjust the influence of each to get the sound you want. [Megatronix] decided to re wire the setup so that one is the left channel and one is the right. Thus providing actual stereo sound from his guitar. This will limit his tonal variation considerably, but should at least serve as a proof of concept. We really want to hear a recording of it in action though.

Doorway Subwoofer

July 26, 2009 by Eliot 26 Comments

doorway

We’ve seen some crazy speaker builds in the past (massive folded horns for example). [DiscoJones] wanted to build a set of speakers that could reach very low frequencies and be very efficient. Instead of constructing a large box, he built a baffle that could be placed in a doorway and use the blocked off room as an enclosure. It has eight 12inch subwoofers, eight midrange drivers, and four tweeters. The speakers are fairly cheap and he built a simple crossover to help them work a little better together. The goal was always deep bass though, so don’t expect very high fidelity from a setup like this.

Adding RDS Decoding To A Vintage Radio

July 24, 2009 by Caleb Kraft 18 Comments

c_670_rds4_sm2 (Custom)

[Edo] wrote in to show us how he added RDS decoding to a radio made in 1957. RDS or Radio Data System is a protocol for data transmission. This allows date, time, artist info, and more to be broadcast along with the music. Its a nice feature that many new cars come with from the factory. [Edo] wanted to add it to his old radio though. He kept the radio stock looking, choosing to use an external LCD to display the data. He has posted the information on where to splice in to add this unit to pretty much any FM radio as well as posting the schematics and source code for the unit itself. Look at the very bottom of the page for the download link, its a bit hidden with the advertisements.