There are a lot of LEGO Mindstorms robots out there, but I finally found the best. Nic_1 is a Johnny V impersonator that detects the direction of sound and follows it. Detection is accomplished by calculating the cross-correlation of two audio signals from the binaural sensor. The data is used to estimate the phase difference between the them. (Videos tracking Kelly Clarkson included!)
I can’t wait any longer for LEGO Mindstorms NXT in August. 32 bits, servos, and mics, oh my!
I spent a few hours tonight fixing everything that was broken on the site.
- Ajax comments work in everything but Opera.
- Enabled automatic dumping of the Rails garbage collector. (no more Rails errors!)
- Fixed some things with the gallery pages. (extra security) There are definately some attempted ‘magic quote’ hacks in the log files. (You must think I am stupid?)
- Rearranged Adsense a little. It may be a few days before I enable this.
You are welcome to test the ajax comments on your favorite obscure browser. They should show up after you hit submit now.
Unfortunately there are no new posts for today.
The popularity of my previous article reminded me of some new record setting LEDs.
In the increasingly popular world of light-emitting diodes (LEDs), an emitter’s light output per given input (efficiency), heat management, and small footprint are critical. So if you can make dramatic advancements in just one of these three areas, you’ve done a lot.
LED performance is quantified by the input power (Watts) required and the output intensity (lumen). A lumen measures the luminous flux (light energy passing) through a particular surface. It accounts for light emitted in all directions. The new Luxeon K2 LED breaks all these barriers.
A white light output at a color temperature of 6500 K with 1500 mA of drive current and a forward voltage of 3.85 V produces 140 lm.
This corresponds to 4 W of input power and 35 lumen per Watt. Comparatively, a standard incandescent bulb emits around 855 lumen at 60 Watts or 14 lumen per Watt. Current LEDs perform at about 20 lumen per Watt. Most professionals don’t expect LEDs to be used for mainstream lighting until they reach about 100 lumen per Watt.
Lately the hoopla concerning LED lighting has been overwhelming. Everyone claims this costs mere pennies to power. I decided to put a new twist on a classic science experiment to prove that LEDs do cost pennies to power. Literally.
Creating a battery from pennies
In order to turn pennies into batteries, another electrode and an electrolyte are needed. In this case, dimes (zinc) are used as the positive electrodes and salt water is used an electrolyte. Copper wire, galvanized nails, and lemon juice are also popular and cheaper solutions. Such a battery produces a differential of about 0.5 volts.
Finding ample power for an LED
Unfortunately, this battery is not enough to light an LED. In order to string eight of these cells in series, an ice cube tray is used. Metal paperclips hang the pennies and dimes into the electrolyte banks. Because the paperclips are conductive, the eight cells are automatically connected in series forming a more powerful battery. This provides a differential of about two volts.
As you may notice, 0.5 volts * 8 != 2 volts. Not all of the banks produced a reliable voltage. In fact, one bank seemed to be working against me.
Lighting a LED with pennies
Generally, LEDs require a resistor to prevent excessive current flow from blowing them out. This project does not require a resistor because the battery simply cannot provide that amount of current.
Connecting the short end of the LED to the penny and the long end to the dime lights up the LED! Everything works as planned. The penny batteries provide about 110 micro-amps of current in series. At two volts, this is only about 220 micro-watts of power!
It does in fact ‘cost’ pennies to power an LED.
Project Photo Gallery
Unfortunately my host has experienced significant downtime this weekend. This is unrelated to any of my sites. Although the site has not been down 24/7, it has been down a lot. In fact, whenever I have had time to post it has been down. The only good thing about this is the backlog of topics I have collected. Look for updates soon!
Scientists at Japan’s NTT Corp. have designed and fabricated silicon transistors that are controlled by the flow of individual electrons.
The amount of energy required to move a single electron increases significantly. That, scientists said, makes it possible to control individual electron motion and current flow…
Low power transistor logic my be ready for an update. Want to see exactly what’s going on? Check out this close up!
This colorized micrograph shows three tunable gates across an electrical channel in a single electron tunneling (SET) transistor.
The good people over at E-DSP have churned out a comprehensive tutorial on how to use an lcd with your electronic devices. The Amtel AVR is their microcontroller of choice because of its cheap programmer. From pinouts to microcontroller code, they make it look easy. In a way it is.
