Imaging The Neighborhood With Solar Panels

January 5, 2018 by Tom Nardi 27 Comments

Like many people who have a solar power setup at home, [Jeroen Boeye] was curious to see just how much energy his panels were putting out. But unlike most people, it just so happens that he’s a data scientist with a deep passion for programming and a flair for visualizations. In his latest blog post, [Jeroen] details how his efforts to explain some anomalous data ended with the discovery that his solar array was effectively acting as an extremely low-resolution camera.

It all started when he noticed that in some months, the energy produced by his panels was not following the expected curve. Generally speaking, the energy output of stationary solar panels should follow a clear bell curve: increasing output until the sun is in the ideal position, and then decreasing output as the sun moves away. Naturally cloud cover can impact this, but cloud cover should come and go, not show up repeatedly in the data.

[Jeroen] eventually came to realize that the dips in power generation were due to two large trees in his yard. This gave him the idea of seeing if he could turn his solar panels into a rudimentary camera. In theory, if he compared the actual versus expected output of his panels at any given time, the results could be used as “pixels” in an image.

He started by creating a model of the ideal energy output of his panels throughout the year, taking into account not only obvious variables such as the changing elevation of the sun, but also energy losses through atmospheric dispersion. This model was then compared with the actual power output of his solar panels, and periods of low efficiency were plotted as darker dots to represent an obstruction. Finally, the plotted data was placed over a panoramic image taken from the perspective of the solar panels. Sure enough, the periods of low panel efficiency lined up with the trees and buildings that are in view of the panels.

We’ve seen plenty of solar hacks, but this one has to be something of a first. Usually people are more worried about maximizing efficiency or tracking the sun with them.

GhettoLED boombox with LED strips lighting up speakers

This Boombox Hack Is Lit

January 5, 2018 by Steven Dufresne 10 Comments

Old boomboxes make great hacks. Their design is iconic; yes they look dated but that really just builds on the nostalgic urge to have one hanging around. Plus their big cases simply invite adding things inside in a way impossible with contemporary electronics.

[Danc0rp] hacked his JVC M70 boombox to make the speakers glow with animated light, bumping VU meters, and a pulsing horizontal bar above the tape deck. The effect is superb. The cones of the speakers act like a projection surface and the grilles hide the LEDs until they activate, and enhance the effects once unleashed. It is one of the best LED speaker hacks we’ve ever seen.

The light effects are provided by LED strips, which for the speakers are attached just inside the outer rim. The brains behind it all is an Arduino UNO. To connect to it, he soldered components to a blank Arduino prototyping board. That board takes input from the boombox’s line-out and does some filtering (an attempt to address some ground noise) before passing the signal on to the Arduino. That board also interfaces between the Arduino and the LED strips. The schematic is available on his GitHub page. He’d like to replace the board with a custom PCB instead and is looking for design help.

The result is not only beautiful but professional looking too. This makes us wonder why boomboxes don’t come this way. See it for yourself in the video below.

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TRS-80 Model 100 Goes Cellular

January 4, 2018 by Al Williams 10 Comments

There are a few old products that have rabid fan bases, and the TRS-80 Model 100 is one of those. Depending on your point of view it’s either a small laptop or a large organizer, but in 1983 it was the ultimate computer on the go. The $1100 version had a whopping 8K of memory and the LCD screen showed 8 lines of 40 characters in glorious monochrome. One cool feature was the built-in 300 baud phone modem, which [Trammell Hudson] wanted to try, but he doesn’t have a landline. He tried a VOiP phone, but it wouldn’t wedge into the acoustic couplers well enough. Then he decided to go cellular.

He had already hooked up an old ITT 500 series dial phone to an Adafruit Fona ceullar board. He even has Teensy software to decode the dial, drive the dial tone and otherwise make the phone work. This time he hooked a handset up through a headset jack.

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Hack Your Own Computer Science Degree

January 4, 2018 by Al Williams 38 Comments

We ran across something interesting on GitHub of all places. The “Open Source Society University” has a list of resources to use if you want to teach yourself computer science for free. We found it interesting because there are so many resources available it can be hard to pick and choose. Of course, you can always pick a track from one school, but it was interesting to see what [Eric Douglas] and contributors thought would be a good foundation.

If you dig down, there are really a few potential benefits from going to college. One is you might learn something — although we’ve found that isn’t always a given, surprisingly. The second is you can get a piece of paper to frame that impresses most people, especially those that want to hire you but can’t determine if you know what you are talking about or not. Lastly, if you go to the right school you can meet people that might be useful to know in the future for different reasons.

The Internet has really changed all of those things, you can network pretty easily these days without a class ring, and there are lots of ways to earn accredited diplomas online. If you are interested in what we think is the most important part — the education — there are many options for that too.

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The Grooviest Random Number Generator Ever

January 4, 2018 by Al Williams 28 Comments

Cloudflare is one of those Internet companies you use all the time, but don’t usually know it. Big websites you visit use Cloudflare to shore up their defenses against denial of service attacks. The company needed some truly random numbers for its security solutions, so it turned to some groovy old tech: lava lamps. In their office is a wall of 100 lava lamps monitored by cameras. The reaction of the lamps is unpredictable, and this allows them to generate really random numbers. [Joshua], a Cloudflare employee, talks about the technical details of the system in a recent blog post.

You might think this is a new and novel idea, but it turns out the LavaRnd (or maybe it is LavaRand — there’s some dispute if you read the comments below) system has been around for a while. In fact, we covered it way back in 2005. Silicon Graphics patented the system in 1996.

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Touch-A-Sketch Gives An Old Toy A New Twist

January 4, 2018 by Kristina Panos 3 Comments

After nearly 60 years and a lot of stairs and squares, there is finally an easier way to draw on an Etch A Sketch®. For their final project in embedded microcontroller class, [Serena, Francis, and Alejandro] implemented a motor-driven solution that takes input from a touch screen.

Curves are a breeze to draw with a stylus instead of joysticks, but it’s still a 2-D plotter and must be treated as such. The Touch-A-Sketch system relies on the toy’s stylus starting in the lower left hand corner, so all masterpieces must begin at (0,0) on the knobs and the touch screen.

The BOM for this project is minimal. A PIC32 collects the input coordinates from the touch screen and sends them to a pair of stepper motors attached to the toy’s knobs. Each motor is driven by a Darlington array that quickly required a homemade heat sink, so there’s even a hack within the hack. The team was unable to source couplers that could deal with the discrepancy between the motor and knob shaft sizes, so they ended up mounting the motors in a small plywood table and attaching them to the stock knobs with Velcro. This worked out for the better, since the Etch A Sketch® screen still has to be reset the old-fashioned way.

They also considered using belts to drive the knobs like this clock we saw a few years ago, but they wanted to circumvent slippage. Pour another glass of your aunt’s high-octane eggnog and watch Touch-A-Sketch draw something festive after the break.

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There Once Was An IC Dedicated To Blinking An LED

January 4, 2018 by Jenny List 56 Comments

Today you can buy flashing LEDs; a simple two-lead component that requires only a power supply to produce even flashes of light. They look for all the world like any other LED, though embedded in the plastic dome is an integrated circuit to do all that flashing work.

There was a time though when a flashing LED was something of a big deal, so much so that National Semiconductor produced a dedicated chip for the task. The LM3909 boasted the ability to flash an LED for over a year using a single C battery. That part is now long out of production, so [Dillon] has implemented the LM3909 circuit using discrete components on a small PCB designed to take pins and fit the footprint of the original.

Why on earth might a reborn LM3909 be of interest to him, you ask? Well, he wasn’t able to make a 555 flash the LED from a coin cell, and a friend mentioned this chip which piqued his interest. The internal schematic is in the data sheet (found in the files section of his project), so he was able to implement it relatively easily using common parts. It still requires an external capacitor just like the original, but there is space on-board should you wish to put it there.

He’s produced a video we’ve placed below the break showing the device in action, proving it to be a drop-in replacement for an original. Recreations of classic chips using discretes are nothing new, we recently brought you a reborn PSU regulator chip made in 2014. An while you’re playing around with coin cell batteries, may we direct your attention to the Coin Cell Challenge.

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