[Todd Harrison] needed a way to run a 12 volt PC fan from mains voltage. Well, we think he really just needed something to keep him occupied on a Sunday, but that’s beside the point. He shows us how he did this in a non-traditional way by using the resistive load of an incandescent light bulb, a diode, and a capacitor to convert voltage to what he needed. You can read his article, or settle in for the thirty-five minute video after the break where he explains his circuit.
The concept here is fairly simple. The diode acts as a half-wave rectifier by preventing the negative trough of the alternating current from passing into his circuit. The positive peaks of the electricity travel through the light bulb, which knocks down the voltage to a usable level. Finally, the capacitor fills the gaps where the negative current of the AC used to be, providing direct current to the fan. It’s easy to follow but the we needed some help with the math for calculating the correct lightbulb to use to get our desired output current.
Continue reading “Light bulb, diode, and capacitor step mains down to 12V DC”
This is the Edison clock, designed by [David Krawczyk]. It shows time in the same way as the multimeter clock, regulating power to two analog needle meters. The feature that makes this one a bit different is the alarm. You can see the series of holes on the front of the base. These have a small light bulb socked in each, and correspond to hours and 5-minute increments. Insert two bulbs to set the alarm time, and make sure that the alarm knob points to ‘on’. As you can see above, the alarm has been set to 8:15. Hidden on the last image of the article above is a PDF with just a bit more explanation. Still, much has been left out so if you replicate this clock we want to hear about it.
[via Gizmodo and Walyou]
Almost a month ago I started trying to reverse engineer an inexpensive LED color changing light bulb. With your help I’ve mapped out the circuit, and taken control of the bulb. But there’s still a few mysteries in this little blinker. Join me after the break to see what I’ve done so far, peruse the schematic and source code, and to help solve the two remaining mysteries.
Continue reading “Part 2: Help me reverse engineer an LED light bulb”
I went to the last monthly meeting of Sector 67, a hackerspace in Madison, WI. One of the things shown off was a color changing LED light bulb that Menards was clearing out for $1.99. Inside there’s two RGB LEDs controlled by an ATtiny13 and powered by an AC/DC buck converter. An ATtiny13 will run you around $1.25 by itself so this price is quite amazing. I grabbed a couple of these bulbs and set to work on them. Join me after the break to see what I’ve got so far.
Update: read a follow-up to this post.
Continue reading “Help me reverse engineer an LED light bulb”
This computer can be mounted in any standard light bulb socket. It uses a pico projector combined with a camera to generate a touch display wherever you shine it. The photo above and the video after the break show the bulb in a motorized lamp arm but that’s just smoke and mirrors, the bulb itself is the core concept. We think there’s real potential for home-built versions. We’ve seen touch displays similar to this that mount on the side of a laptop, but why have the computer around at all? Ditch the USB connection for wireless and have it connect to your home server for processing power. It becomes a perfect solution for places that aren’t traditionally computer friendly. For instance, that kitchen computer you don’t want to touch with dough-encrusted hands becomes washable when the display is projected on a cutting board. Continue reading “Light bulb form-factor computer”
[SeBsZ] tipped us off that he’s working on a display using RGB LEDs. He’s etched some nice surface mount controller boards to carry the ATmega8 microcontroller and NXP PCA9635 drivers. This setup uses the I2C bus to address each expansion board of 5 LED modules. Theoretically this hardware would allow for 638 RGB modules but because of power and refresh rate issues he’s set his sights on reaching somewhere between 100-125, a total of about 25 expansion boards.
There’s not a ton to show off yet. But we expect big things from the project. Partly because one of his goals is to generate a display that can be rolled up and easily moved, and partly because his large-scale light bulb displays are so impressive. Take a look at the video of his 60-bulb unit after the break.
Continue reading “RGB display development”