Sunday, November 25, 2007

Don't Buy Hampton Bay Solar Lights!

I bought two boxes of 4 each Hampton Bay #498-959 Solar Garden Lights at Home Depot. After about two years operation, the translucent plastic housing became brittle and fell apart. This plastic is not sunlight resistant! I wrote to Home Depot a complaint, but got no reply. For those who would like to know how to Hack a solar light and use them for other purposes, here is a pdf of the construction. Perhaps you should wrap aluminum foil around the translucent plastic housing to keep the sunlight from destroying the plastic.

Thursday, November 22, 2007

Electronic Candle

Build yourself a electronic candle that is safe from fire. I found a great program to load in a 12f675 PIC microcontroller from a website named Mondo Technology. I changed the circuit to allow using a mosfet to flicker a 12 volt light bulb to simulate the candle. I mounted the bulb inside a glass star to complete the effect.

The circuit can be built on a piece of prefboard. The circuit is attached between the lamp inside the star and the dc power source. You can get my version of the schematic here. You can also view a movie at Youtube here.

Sunday, September 30, 2007

Wind Harp on SHOUTcast

I stopped using windows media encoder to broadcast my wind harp. I'm now using Shoutcast. You can go to the website and get the latest copy of shoutcast server. The software will allow you to become an instant internet radio station. You will also need to get a copy of winamp and the winamp DSP plug-in. Its all free! An excellent tutorial and manual on how to set up a Shoutcast station can be found here. My harp can be heard here. If its not listed, check later, it may be down for maintenance.

I play live recordings of the harp on my station and update every few days. The recordings get better as I improve the recording technique. When planes and helicopters fly overhead, the strings resonate and make some interesting effects. Other effects can be caused by insects landing on the strings or birds pecking at them. The strings will also react to loud nearby noises, tree branches swaying against the structure, cats jumping on the roof, trains blowing the horn.

The electronics used to amplify the tiny signals from the pickups, are solar powered and have rechargeable batteries for backup power at night.

Just about all the files can be downloaded at my files storage site. 45 files at the date of this writing. With the rainy season coming, many more interesting recordings are to be made.

Remember to tune in my station and "listen to the wind" in a whole new way.

A LM386 is used for a simple preamp. I had some PC boards made for the circuit. See previous blogs about the development of the preamp.

Magnetic sensors (hand wound) pickup the sounds from the center strings. Two sensors are used to "buck out" the hum from surrounding EMF.

Photo of the 4 string wind harp on my shed. To the left are the solar garden lights that power the harp. Sounds are picked up from the two center strings by magnetic sensors. The two outer strings transmit their vibrations through the supporting frame. To protect from the rain, I throw a plastic cup over the coil assembly.

Friday, July 27, 2007

Wind Harp Live!

Its not too difficult to add live audio to your own web page. You will need to get Windows Media Encoder, a free program found here. To broadcast the sound on the internet, I connected the harp to the microphone input of my PC and run Windows Media Encoder. A good tutorial on setting up live broadcasting can be found here. For the listener to hear the harp, I made a web page to launch Windows Media Player using the HTML code example found at this webpage . If it is windy and I actually have Windows Media Encoder running, you should be able to connect by going to My Wind Harp page.
You can learn more about my wind harp project by viewing some of my earlier blogs about the subject.

Saturday, July 21, 2007

Simpler Solar Powered Preamp

Usually the best solution is the simplest solution. I'm using a LM386 now for the preamp in my Wind Harp. The LM386 has low power needs and has good tonal quality, plus its use as a preamp is simple and efficient. I will also use two solar garden lights wired in series to supply power. To draw power from the solar lights just simply connect a set of leads from the the battery holder terminals. Bring out the wires and connect in series. Below is the schematic and photos of the solar lights.

The schematic of the preamp using the LM386 and two garden lights.

Remove the screws that hold the two halves of the garden light together. Solder wires to the battery holders inside the garden lights and connect in series.

Closeup showing circuit board (perfboard), connectors for power, input and output. Hide all this wiring inside the bottom bowl of the garden light.

For more info about garden lights and how they work, visit "Garden Light Autopsy" at my website here. Or get the pdf here.

Friday, July 20, 2007

Improved Preamp for Wind Harp

I did some changes to the wind harp preamp, some of which Acme Fixer (see previous blog) suggested. Moving the preamp at the harp also reduced a lot of the 60hz pickup. I posted at You Tube a video of the waveform as shown by Visual Analyzer 8.

View the YouTube video here.

Improved circuit:

Saturday, July 14, 2007

Preamp for Wind Harp

I built a preamp circuit for use with the wind harp. The amplifier uses a J-fet transistor to connect to a magnetic pickup without loading down the pickup too much. The rest of the circuit brings up the gain enough to drive a set of Amplified PC Speakers.

Bread boarded circuit while in the design phase. That mess really works!

The preamp can also be plugged into the microphone input on a PC. Dual coil design is next to test out as a method to buck out hum. Right now, I'm just using a single coil with a magnet as the pickup. The circuit is still a "work in progress" and has not been finalized. I will post the final tweeks when done.

You can download a pdf of the schematic HERE

I also made a Youtube video of the waveform. View it HERE
The video shows a predominate frequency at about 440 hz and low frequency ripple from hum and vibration of the mount. When a truck drives by it will increase. More work on the preamp can be done to remove this.

You can listen to the harp "Live", if I have Windows Media Encoder on. Just open Windows Media Player, click "File","URL" then copy and paste this URL:

I used a freeware oscilloscope/FFT program to view the signal. Get it HERE

The author of Watson's eBlog has been very helpful in my design of the preamp. He also has an excellent design of a preamp of his own for bringing the sounds of the outdoors inside. The site can be found HERE

Saturday, July 7, 2007

Wind Harp Experiments

After reading a lot about wind harps and hearing the awesome sounds they make, I decided to give it a try. I strung a steel wire between two "C" clamps separated by almost eight feet. The support is a 2" by 2" by 8 feet long pine stud I got from Home Depot. Each C clamp has a hole drilled on the side with a eye bolt installed to support the wire. The eyebolt is tensioned untill a nice tone is heard when plucked.

Photo on the left show pickup placed near the wire.

Photo on the right show the whole thing, about 8 feet high.

So I don't have to use a sounding board to make the sounds audible, I used a magnetic pick up and a Radio Shack amplifier to amplify the delicate vibrations. As the wind "plucks" the string, musical notes and harmonic vibrations could be heard.

A 3 inch C clamp holds the wire on each end.

You can hear what my wind harp sounds like at this link.

The Harp I made just uses one string to prove it works. Now imagine using several strings.

Wednesday, July 4, 2007

Wind Harps

I found an interesting wind harp design at this website . Wind Harps or more correctly called an Aeolian Harp is played by the wind. The wind causes the string to vibrate and if several strings are tuned to the same pitch, these sounds reinforce and modulate between themselves. The resulting sounds create a serene and peaceful melody. Such an instrument can be made with PVC pipe and nylon fishing line. The above website has a list of materials and full instructions on how to make one.

Saturday, June 30, 2007

Tech Shop

Today was Open House Day for the Tech Shop. Located in Menlo Park, Ca.

The Tech Shop is an open source shop where you can go to build things. For $100 a month you get access to mills, lathes, welders, benders, and a super cool laser cutter. You get basic training for using machines for a small fee. Got a robot you want to build for battlebots? or want to do some sand casting for Burning Man? You have no garage or your neighbors don't like all that grinder noise? Then this is the place to be. The greatest thing for the geek without a garage.

See some photos I took: My Picasa Album

Friday, June 29, 2007

Time Lapse at Robogames 2007

Here is a time lapse of the activities at Robogames 2007 (June 14-17). A photo was taken every 10 seconds. Even at night when the public went home, some of the combat team members were working hard.

2 AM Saturday and someone is still working on their Bot. Team dedication! Hey, where's the rest of the team? Click Here for the Time Lapse Movie

Plastic Wind Organs

It's pretty common to see and hear wind chimes outside of peoples homes. But how about something different.

Those two liter plastic soda bottles make great Wind Organs.

Here is the website where I got the idea.

They really sound great when the wind really gets going.
I plan to set up a whole row of these things and let the wind blow.

Aeolian Laboratory for other sounds.

A Electronic Didgeridoo

Project Start: June 29,2007

The start of a new project

I want to build an instrument that will sound like a Didgeridoo.

The instrument will be a free standing constructed unit that will not use a computer. Sound generation will be digital and constructed using discreet components and PIC microcontrollers.

The instrument will be played using hand controls similar to playing a Theremin. Hand position will be sensed with IR distance measuring sensors. One hand controls the pitch and the other hand controls the volume.

For an instrument to sound like that of a real Didgeridoo, I will be using Wav files of the real thing. These Wav files are binary representations of sound that can be pushed through a DAC, then through an amplifier. Wav files can be stored on a eprom and then counted through in real time to make the sound. Pitch can be controlled by changing the clock rate. Volume can be controlled by changing the attenuation before reaching the amplifier.

Timelapse video of experimental breadboarding.


This website by Harry Lythall shows how wav files can be converted directly to sound using a DAC.

So what does a Didgeridoo sound like? This link has some wav files and explains how a Didgeridoo works.