Hacklet 98 – Underwater ROVs

March 5, 2016 by Adam Fabio 5 Comments

A few motors, propellers, a camera, maybe a wire tether, and some waterproof electronics. Throw it all together and baby you’ve got an underwater Remotely Operated Vehicle (ROV) cooking! It all sounds simple on the surface, but underwater ROVs are a tough challenge. We’ve all seen deep-sea ROVs searching the wreck of the Titanic, or working to stop the flow of oil below the Deepwater Horizon. Plenty of hackers, makers, and engineers have been inspired to build their own underwater ROVs. This week on the Hacklet, we’re spotlighting at some of the best ROV projects on Hackaday.io!

We start with [Tim Wilkinson] and BorgCube ROV. [Tim] has jumped into the world of underwater ROVs with both feet. BorgCube is designed to operate in the unforgiving salt waters of the Pacific Ocean. This ROV can see in stereo, as [Tim] plans to use a head mounted VR display like the Oculus Rift to control it. [Tim] wanted to use a Raspberry Pi as the brains of this robot. Since the Pi Compute module can handle two cameras, it was a natural fit. The electronic speed controls are all low-cost Hobby King R/C car units. [Tim] created a custom circuit board to hold all 12 ESCs. This modular design allows individual controllers to be swapped out if one meets an untimely doom. BorgCube is just getting wet, but with 37 project logs and counting, we’re sure [Tim] will keep us posted on all the latest action!

Next up is [MrCullDog] with Luna I ROV. Inspired by a professional underwater ROV, [MrCullDog] decided to build a deep diving unmanned vehicle of his very own. Like BorgCube above, many of Luna I’s motors and drive components come from radio controlled hobby electronics. [MrCullDog] is bringing some 3D printed parts into the mix as well. He’s already shown off some incredibly well modeled and printed thruster mounts and ducts. The brains of this robot will be an Arduino. Control is via wired Ethernet tether. [MrCullDog] is just getting started on this project, so click the follow button to see updates in your Hackaday.io Feed.

Next up is [Edward Mallon] with The Cave Pearl Project. Not every underwater system needs motors – or even a human watching over it. The Cave Pearl Project is a series of long duration underwater data loggers which measure sea conditions like temperature and water flow. [Edward’s] goal is to have a device which can run for a year on just three AA batteries. An Arduino Pro Mini captures data from the sensors, time stamps it, and stores it to a micro SD card. If the PVC pipe enclosure keeps everything dry, the data will be waiting for [Edward] to collect months later. [Edward] isn’t just testing in a swimming pool, he’s been refining his designs in open water for a couple of years now.

If you want to see more under (and above) water projects, check out our updated waterborne projects list! If I missed your project, don’t be shy! Just drop me a message on Hackaday.io. That’s it for this week’s Hacklet. As always, see you next week. Same hack time, same hack channel, bringing you the best of Hackaday.io!

Materials To Know: Acetal And Delrin

March 3, 2016 by Gerrit Coetzee 65 Comments

Delrin, Acetal, and its many trade names is a material properly known as Polyoxymethylene or POM. It is one of the strongest plastics and is a good go-to material when you want the best properties of plastic, and don’t need the full strength of a metal part. It was originally formulated to compete with Zinc and Aluminum castings after all.

I won’t go too deep into the numbers behind POM. If you need the Young’s Modulus, you probably don’t need this guide. This is intended to be more of a guide to its general properties. When you’re looking for something to fit an application it is usually easier to shift through the surface properties to select a few candidates, and then break the calculator out later to make sure it will work if you’re uncertain about the factor of safety.

The most popular property of POM is its ease of machining. While doing this research every single site I came across referred to it as the most machinable plastic. That’s about as objective as subjective praise can get. It doesn’t tend to grab tools like, for example, HDPE. It also chips nicely unlike UHMW and Nylon. Some plastics, like UHMW, have the unfortunate tendency to render the dials on a mill or lathe meaningless as the plastic deflects away from the tool. POM does not do this as much. Of course these other plastics have their strengths as well, but if any plastic will do, and you’re machining, POM is a very good choice.

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Transforming Spice

March 2, 2016 by Al Williams 13 Comments

Spice is a circuit simulator that you should have in your toolbox. While a simulator can’t tell you everything, it will often give you valuable insight into the way your circuit behaves, before you’ve even built it. In the first installment of this three-part series, I looked at LTSpice and did a quick video walkthrough of a DC circuit. In the second, I examined two other parts of Spice: parameter sweeps and AC circuits. In this final installment, I want to talk a bit more about real-world component performance and also look at modeling transformers.

Recap

Last time we looked at a low pass filter, but it wasn’t practical because the components were too perfect. Only in simulation do voltage sources and wires have zero resistance. There was no load resistance either, which is unlikely. Even an oscilloscope probe will load the circuit a little.

The resulting AC analysis showed a nice filter response that was flat to about 1 kHz and then started roll off as the frequency increased. Suppose the source had an 8 ohm series resistor. How does that change the circuit response?

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Spice Power

February 29, 2016 by Al Williams 8 Comments

Spice is a circuit simulator that you should have in your toolbox. While a simulator can’t tell you everything, it will often give you valuable insight into the way your circuit behaves, before you’ve even built it. In the first installment of this three-part series, I looked at LTSpice and did a quick video walkthrough of a DC circuit. This time, I want to examine two other parts of Spice: parameter sweeps and AC circuits. So let’s get to it.

In the first installment, I left you with a cliffhanger. Namely the question of maximum power transfer using this simple circuit. If you run the .op simulation you’ll get this result:

--- Operating Point ---
V(n001): 5 voltage
I(R1): 0.1 device_current
I(V1): -0.1 device_current

The power in R1 (voltage times current) is .5 W or 500 mW if you prefer. You probably know that the maximum power in a load occurs when the load resistor is the same as the source resistance. The Rser parameter sets the voltage source’s internal resistance. You could also have created a new resistor in series with V1 and set it explicitly.

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Hackaday Links: Leap Eve, 2016

February 28, 2016 by Brian Benchoff 3 Comments

The current Mac Pro is a masterpiece of design that looks like a trash can. We’ve been waiting for someone to take one of these computers and stuff a MiniITX board in there, but seeing as how the Mac Pro costs $3000, that probably won’t happen anytime soon. Here’s the solution. It’s a trash can computer case that is also too expensive for what it is. Now all we need is someone to put a big fan inside one and turn this computer into a wacky waving inflatable arm flailing tube man.

[Mike Harrison] recently got his hands on a $20,000 SPARC CPU module. This is an enormously thick board that must be dozens of layers thick. How many layers was an open question until he put the board in a CNC milling machine. The setup is pretty much what you would expect with a few lines of g-code repeated over and over. The real trick comes from using one of the outputs for lubricant to trigger the shutter release on a camera. How many layers were in the CPU module? About 30, or something like that.

Almost a year ago, we saw the latest advances in perfboard. It was a perfboard with each hole connected to rows and columns on a selectively solderable orthogonal busses. Something like that. Actually, we still can’t wrap our head around it. Now, it’s a crowdfunding campaign with a few new and useful features. There’s also a layout tool that will show you where to place your components and where to make solder bridges.

[Ray Wilson] started Music From Outer Space, the place to learn about DIY analog synthesizers. Ray now has cancer, and as you can imagine, being a self-employed engineer specializing in analog synthesizers doesn’t provide great health coverage. [Ray]’s family set up a GoFundMe page to pay for the medical expenses.

We haven’t seen much in the land of 3D scanners, and we’re betting most of that is because they’re so expensive. The guys from CowTech have a kickstarter up for a 3D scanner that’s just $99. It’s based on the Ciclop scanner but designed around a custom Arduino shield and remains fully open source.

Remember the screen printed electroluminescent displays that were printed directly onto t-shirts from a few months ago? Now that company is working on a much cooler design: the Hackaday Jolly Wrencher. It works, but there are still a few problems: they’re setting the shirt on fire a little. Don’t worry, if these are ever reasonably safe and somewhat affordable, an EL Jolly Wrencher shirt will be in the Hackaday Store.

Need a rechargeable multimeter? It’s actually pretty easy. With an 18650 Lithium Ion cell and a 9V boost converter, this circuit will fit in most devices that need a 9V battery. To do this right, you’ll also need a USB charging port, to be used once every couple of years when the battery needs charging.

Hacklet 97 – Camera Projects

February 26, 2016 by Adam Fabio 9 Comments

We last covered camera projects way back in Hacklet #11. A ton of camera projects have been added to Hackaday.io since then. While the rest of the world is taking selfies, hackers, makers, and engineers have been coming up with new ways to hack their image capture devices. This week on the Hacklet, we’re taking a look at some of the best camera projects on Hackaday.io!

First up is [aleksey.grishchenko] with PiXel camera. PiXel is a camera and a live video display all in one, We wouldn’t exactly call it high-definition though! A Raspberry Pi uses its camera module to capture images of the world. [Aleksey] then processes those images and displays them on a 32 x 32 RGB LED matrix. This matrix is the same kind of tile used in large outdoor LED signs. The result is a surreal low resolution view of the world. Since the Pi, batteries, and camera all hide behind the LED matrix, there is an unobstructed view of the world around you. [Aleksey] used [Henner Zeller’s] matrix library to make this hack happen.

Next up is [Esben Rossel] with Linear CCD module. [Esben] is building a Raman spectrometer, much like 2014 Hackaday Prize finalist [fl@C@] with his own ramanPi. The heart of a spectrometer is the linear image capture device. Both of these projects use the same TCD1304 linear CCD. Linear Charge Coupled Devices (CCDs) are the same type of device used in flatbed document scanners. The output of the CCD is analog, so an ADC must be used to capture the data. [Esben] is using an STM32F401RE on a Nucleo board as the control logic. The ST’s internal ADC converts the analog signal to digital. From there, it’s time to process all the spectra.

[Chiprobot] brings the classic Wii remote camera to the internet of things with
ESP8266 meets Wii Mote Camera. The Wii remote uses a camera which doesn’t output images, instead it plots the location of up to four IR LEDs. Normally these LEDs are located in the poorly named sensor bar that is sold with the Wii. Hackers have been using these cameras in projects for years now. [Chiprobot] paired his camera with the modern classic ESP8266 WiFi module. The ‘8266 is programmed to read data from the camera’s I2C bus. It then sends the data as an SVG request to the W3C website. W3C returns a formatted image based on those coordinates. The resulting image is a picture of the IR LEDs seen by the camera. Kind of like sending your negatives out to be developed.

Finally, we have [GuyisIT] with Raspberry Pi Photobooth. Photo booths are all the rage these days. First it was weddings, but now it seems like every kids party has one. [GuyisIT] didn’t rent a booth for his daughter’s birthday, he built one using his Raspberry Pi and Pi camera. The project is written in python, based upon [John Croucher’s] code. When the kids press a button, the Pi Snaps a series of pictures. The tiny Linux computer then joins and rotates the images while adding in some superhero themed graphics. Finally the Pi prints the image on to a photo printer. The biggest problem with this hack is re-triggering. The kids loved it so much, they kept pressing the big red button!

If you want to see more camera projects, check out our updated camera projects list! If I missed your project, don’t be shy! Just drop me a message on Hackaday.io. That’s it for this week’s Hacklet. As always, see you next week. Same hack time, same hack channel, bringing you the best of Hackaday.io!

Adding Spice To Your Workbench

February 26, 2016 by Al Williams 43 Comments

Most of us didn’t fight in World War II, drive a race car, or fly the Space Shuttle. But with simulation, you can experience at least some of what it would be like to do those things. Granted, playing Call of Duty isn’t really the same as going to war. No matter what you are simulating, it only goes so far. However, you can get a lot of value from a simulation. I’d bet the average kid who has played Call of Duty knows more about WWII locales and weapons than my high school history teacher.

When it comes to electronics, simulation is an excellent way to get insight into a circuit’s operation. After all, most circuits operate in the abstract–you can’t look at an audio amplifier and see how it works without a tool like a scope. So simulation, when done well, can be very satisfying. You just have to be careful to remember that it isn’t always as good as the real thing.

That’s Spicy

One of the best-known electronics simulators is Spice, which Berkeley created in 1973. In its original form, you had to punch cards that described your circuit and the analysis you wanted to perform. Modern PC versions sometimes replace the deck of cards with a text file. The best modern versions, though, give you a GUI that allows you to draw a schematic and then probe it to see the results.

There are several paid and free versions of Spice (and other simulators) that include a GUI. One of the best for a casual user is the free offering from Linear Technology called LTSpice.

Linear makes LTSpice available and populates it with models for their devices in the hopes you’ll buy components from them. However, the software is entirely usable for anything, and it has a powerful set of features. Linear produces the software for Windows, but I can attest that it runs just fine under Wine on Linux. The Web site will invite you to register, but you don’t have to if you don’t want to.

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