Aperiodic musings from a coder.
Archive for January 2009
Midnight Research Labs describes a nifty theremin hack implemented by detecting signal strength of a WIFI signal. Python source is available to examine.
Bonus Hack: Zevv implements an ultrasonic theremin, emitting ultrasonic chirps from laptop speakers, detecting reflection to the microphone, and driving a tone generator.
Pix from neighborhood of Dog Canyon in southern New Mexico, 2008.
Related Posts: What We Hike 2, What We Hike
Check out our new blog theme: now with more bacon.
25 years ago today, Sony Corporation of America v Universal City Studios, Inc was decided by the Supreme Court of the United States, affirming that time-shifting is fair use and does not infringe on copyright.
[flash http://www.youtube.com/watch?v=xoDr_04-CMs] [video link]
We had the opportunity to explore Las Vegas, New Mexico (not the other one).
Old western towns along the rail line tended to have one fancy hotel to make a good impression on visitors, and the Plaza Hotel on the square of Las Vegas has been restored. We took a room, and can recommend a stay for history fans.
Las Vegas has over 900 buildings listed on the National Register of Historic Places. Take a random walk and absorb the architecture.
Carnegie Library, 1903, only surviving Carnegie Library in New Mexico, with a nod to Monticello
Related Posts: What We Tour
We often use a Plantronics Voyager 510 Bluetooth headset with our computer, so we can a) listen to streaming video/audio without inflicting our choices nearby innocents, and b) remain untied by a corded headset when we jump up with sudden inspiration.
A previous post explored building a USB charger for our cell phone, and we decided to try the same thing to charge our headset. Over time, we are trying to reduce the number of wall-wart chargers used with our laptop, so we don’t have to carry chargers on business trips and to eliminate wasted electricity when the charger is plugged into a wall socket and not charging a gadget. The USB charger for our cell phone used zero standby current, and we hoped to do the same for the headset charger.
A USB port can supply 100mA at 4.75 to 5.25volts. A higher current, to a maximum of 500mA, can be drawn if the port follows a particular handshaking protocol.
|
Pin |
Color |
Name |
|
1 |
Red |
VBus(5V) |
|
2 |
White |
D- |
|
3 |
Green |
D+ |
|
4 |
Black |
Gnd |
The headset charger has a barrel type plug with diameter 3.0mm and only 3.5mm in length. Notice that the barrel has a reduced diameter region near the end to help the headset “grip” the plug.
The open-circuit voltage measures 5.5V, and the charging current was 63.8mA. This is within the 100mA current limit of USB, and the voltage is close enough to the USB supply voltage that we suspect a direct connection to the VBus and Gnd conductors of a USB cable will successfully keep the headset charged. See the “Design and Experiment” section of a previous article for more in-depth hand-waving.
Usual Disclaimer: Use this information at your own risk. We are not responsible for damage to your headset or computer.
We couldn’t find a similar connector anywhere on Digikey or other electronics parts vendors we searched. (If anyone has found a source, let us know.) Reluctantly we purchased a spare charger on Ebay for less than $5, just to salvage the connector.
Take a spare USB cord and cut off the series “A” type plug, leaving a few centimeters of cable. Remove a centimeter of outer insulation and shield, exposing four wires. You can cut off the green (D+) and white (D-) wires– they are not needed here.
Cut the spare charger cable 10cm from the connector end, and remove one cm of outer insulation, exposing a red and yellow wire. The red connects to the inner conductor of the plug, 5V, and the yellow connects to outer GND.
Strip insulation 0.5cm from the wires. Thread a length of shrink-wrap tubing on the cable, and twist the red wires together and solder. Twist the yellow wire from the charger plug to the black wire from the USB plug, and solder.
Use a bit of electrician tape to insulate the conductors, and wrap more around both wires for strain relief.
Check continuity with a meter. Slip the shrink wrap tubing over the solder joints and apply gentle heat until snug.
It works!
Related Posts: V176 Cell Phone USB Charger, Power to the Programmers
[flash http://www.youtube.com/watch?v=noe3kR8KqJc] [video link]
[flash http://www.youtube.com/watch?v=pDc9I3z7ab4] [video link]
[flash http://www.youtube.com/watch?v=B9WP8Zwu260] [video link]
[flash http://www.youtube.com/watch?v=yX8yrOAjfKM] [video link]
Related Posts: Tech Support Film Festival, Theremoid FilmFest, Theremin Video Film Festival
The USA DTV coupon program is out of money. The vouchers are intended to help purchase digital converter boxes for consumers with older televisions (and analog TV tuner cards) needed to convert digital broadcasts to the legacy format after the February 17, 2009 deadline for stopping analog broadcast TV. $1.34 billion was reserved for the program.
Now the advocacy group Consumers Union is urging a delay in the transition date.
[kudos Gizmodo, Washington Post]
Related post: Switching to Digital TV