This isn’t the first time we’ve seen DIYers sending music over a laser beam but the brothers [Armand] and [Victor] are certainly in contention for sending the music the longest distance, 452 meter/1480 feet from their building, over the tops of a few houses, through a treetop and into a friend’s apartment. The received sound quality is pretty amazing too.
In case you’ve never encountered this before, the light of the laser is modulated with a signal directly from the audio source, making it an analog transmission. The laser is a 250mW diode laser bought from eBay. It’s powered through a 5 volt 7805 voltage regulator fed by a 12V battery. The signal from the sound source enters the circuit through a step-up transformer, isolating it so that no DC from the source enters. The laser’s side of the transformer feeds the base of a transistor. They included a switch so that the current from the regulator can either go through the collector and emitter of the transistor that’s controlled by the sound source, giving a strong modulation, or the current can go directly to the laser while modulation is provided through just the transistor’s base and emitter. The schematic for the circuit is given at the end of their video, which you can see after the break.
They receive the beam in their friend’s apartment using solar cells, which then feed a fairly big amplifier and speakers. From the video you can hear the surprisingly high quality sounds that results. So check it out. It also includes a little Benny Hill humor.
Continue reading “Sending Music Long Distance Using A Laser”
This is weird science. Researchers at Lawrence Berkeley National Laboratory have taken some normal bacteria and made them photosynthetic by adding cadmium sulfide nanoparticles. Cadmium sulfide is what makes the garden-variety photoresistor work. That’s strange enough. But the bacteria did the heavy lifting — they coated themselves in the inorganic cadmium — which means that they can continue to grow and reproduce without much further intervention.
Bacteria are used as workhorses in a lot of chemical reactions these days, and everybody’s trying to teach them new tricks. But fooling them into taking on inorganic light absorbing materials and becoming photosynthetic is pretty cool. As far as we understand, the researchers found a chemical pathway into which the electrons produced by the CdS would fit, and the bacteria took care of the rest. They still make acetic acid, which is their normal behavior, but now they produce much more when exposed to light.
If you want to dig a little deeper, the paper just came out in Science magazine, but it’s behind a paywall. But with a little searching, one can often come up with the full version for free. (PDF).
Or if you’d rather make electricity, instead of acetic acid, from your bacteria be our guest. In place of CdS, however, you’ll need a fish. Biology is weird.
Headline images credit: Peidong Yang
Forget the soup cans connected by a piece of string. There’s now a way to communicate wirelessly that doesn’t rely on a physical connection… or radio. It’s a communications platform that uses lasers to send data, and it’s done in a way that virtually anyone could build.
This method for sending information isn’t exactly new, but this project is one of the best we’ve seen that makes it doable for the average tinkerer. A standard microphone and audio amplifier are used to send the signals to the transmitter, which is just a typical garden-variety laser that anyone could find for a few dollars. A few LEDs prevent the laser from receiving too much power, and a solar cell at the receiving end decodes the message and outputs it through another amplifier and a speaker.
Of course you will need line-of-sight to get this communications system up and running, but as long as you have that taken care of the sky’s the limit. You can find incredibly powerful lasers lying around if you want to try to increase the communication distance, and there are surprisingly few restrictions on purchasing others that are 1W or higher. You could easily increase the range, but be careful not to set your receiving station (or any animals, plants, buildings, etc) on fire!
Continue reading “Solar-Cell Laser Communication System”
[sudarshan] is a solar hobbyist and needed a way to cut solar cells for his projects. He had previously created a rotary tool saw but manually feeding them through was sketchy at best. With just a slight wrong movement of his hand or flex in the work surface would cause the cell to break. These cells are extremely brittle and break easily. He needed a method of cutting these cells that was free from jitters and would cut in a straight line. He looked around his junk bin and found an odd solution… a scanner. Yes, the type you would scan photos in your computer with. The scanner had two critically important features, a flat surface and a carriage mechanism that moves perfectly parallel with that flat surface.
[sudarshan] made a solar cell cutting mini table saw with that scanner and made the cutting happen automatically. He mounted a motor with a diamond saw disk to the carriage, that is responsible for the cutting. The blade was positioned just high enough to poke through the plexiglass that replaced the original glass bed. A power switch turns on the cutting disk motor and an Arduino was used to move the carriage, including the cutting blade, back and forth. Two of the stock scanner buttons were reused and wired to the Arduino to keep the saw looking good.
The first few passes of the saw were done to cut a slot in the plexiglass. In order to cut a solar cell, the cell is taped to the bed with the desired cut location aligned with the slot in the plexiglass bed. Once everything is set, hit the ‘go’ button and the saw blade is slowly pushed through the cell, leaving a straight, clean cut.
Continue reading “Automated Table Saw Cuts Photovoltaic Solar Cells”
This solar monitoring project was entered in The Hackaday Prize and didn’t make the semifinal cut, but it is worth featuring on the site because we think that it is pretty cool. The idea started all the way back in May of 2013 when [Michel] was planning to attempt to bring his house totally off the grid in an effort to become as independent from the local Utility company as possible. After a bit of calculating, he figured out that the solar cells on the roof could potentially provide about 80% of the power needed, which of course took into account the lack of sun during the winter months in his area.
[Michel] posts a lot of the technical details on the Hackaday.io page and lists the components that were required to set up this system. At night, a lighting mechanism shows whether the building is being run off of the Photovoltaic (PV) System or if it is getting power from the grid. He states in the projects logs why it is important to monitor the solar cells and provides some amazing graphs of the data that was recorded through the energy-intelligence platform that he integrated into his home. An example can be seen posted below. A few quick specs of the project include the solar field being made of 16 solar modules providing 4300 Wp (Watts – peak) of electrical power. The system comes with a comprehensive remote control as well. We like this idea a lot. Now, would you install something like this up on your own home or office? Let us know in the comments.
This project is an official entry to The Hackaday Prize that sadly didn’t make the quarterfinal selection. It’s still a great project, and worthy of a Hackaday post on its own.
Continue reading “Extrinsic Motivation: Off-grid Solar System Monitoring Solution”
[Rusdy] is building a solar charger for his electric bike, and quickly realized the lithium cells in his bike wouldn’t work well with the most common charge controllers out there. Solar cells have an IV curve, of course, and this changes with the amount of sunlight, requiring some conversion circuitry. Most of the charge controllers out there operate in buck mode, but the commercial boost mode converters [Rusdy] needed for his 36V battery are pricey as all get out. What was [Rusdy] to do? Build his own Boost MPPT solar charger, of course.
The circuit used for the charge circuit is fairly similar to a boost converter, with a little bit of logic required to get the maximum power out of the solar cells. [Rusdy] had an Arduino lying around, so that took care of the logic, and by sampling the voltage and current with the analog pins, he can turn a MOSFET on and off to get the most out of his solar cells.
The finished product works perfectly with an efficiency greater than 87%. Charging current and the final trickle charge is adjustable through software, allowing [Rusdy] to get the most out of his solar panels and electric bike. The board itself is just a prototype and could use a layout revision, but we’ve got to hand it to him for cloning a >$300 charge controller with an Arduino and a few scraps in a part drawer.
Here’s a photovoltaic cell that can be printed onto paper. The manufacturing technique is almost as simple as using an inkjet printer. The secret is in the ink itself. It takes five layers deposited on the paper in a vacuum chamber. But that’s a heck of a lot easier than current solar cell fabrication practices. In fact, is sounds like the printing process is very similar to how potato chip bags are made. This is significant, because it could mean a fast track to mass production for the technology.
It isn’t just the easy printing process that excites us. Check out the video after the break where a test cell is placed on top of a light source while being monitored by a multimeter. It’s been folded like a fan and you can see a researcher sinch up the cell into a small form for storage. It’s a little counter-intuitive; for instance, you wouldn’t want to make a window shade out of it because it would have to be down during the day to get power. Be we think there’s got to be some great use for these foldable properties. Continue reading “Printable solar cells that can be folded up when not in use”