Why hello there!
I'm Bob, a Computer Science graduate
student at from Cal Poly, San Luis Obispo. I received my Bachelors degree in Computer Engineering from Poly in June of 2010 and my Masters degree in Computer Science in June of 2012.
My graduate focus was in graphics, although I also enjoy the fields of security and embedded systems. My personal and academic projects have given me fun things to do, like building a Christmas light animation system from scratch, designing vehicle electronics for some of the most fuel-efficient vehicles on the planet on the Cal Poly Supermileage Team, and writing a GPGPU Monte Carlo ray tracer in CUDA and C++.
I worked as a Code Junkie for iFixit from June 2011 through July of 2012. Next I worked as an R&D Rendering Engineer at DreamWorks Animation. Currently, I work as a Robotics Engineer at a stealth mode startup.
In a past life I worked at Cisco Systems, where I wrote an internal SNMP performance testing tool for their biggest and baddest routers and worked in R&D developing UI prototypes for some patent-pending tech.
What was that about Chistmas lights?
Yeah! Man, what a fun project!
The lights are controlled by 4-outlet gang boxes out in the yard. They have a single AC power input and a Cat-5 jack that sends logic-level signals that turn each channel of lights on an off.
The boards inside each gang box are pretty simple. A 5V logic-level signal (coming in over Cat-5) flips on a triac through an opto-isolator. Triacs are like transistors for AC signals. Opto-isolators consist of an LED that trips a photo-detector when it's turned on. That keeps my high-voltage AC and low-voltage DC circuits completely electrically isolated. The output of each triac is wired up to its corresponding outlet.
The whole show is controlled via some free light sync software called Vixen. Vixen talks to my custom FPGA lighting controller to turn each channel on or off at the appropriate time. The controller I designed has an AC input to synchronize with the sine wave so all 32 channels are dimmable!
And those super fuel-efficient vehicles?
Another fun project. The Cal Poly Supermileage Team designs, builds, and races its vehicles in the Shell Eco-marathon Americas. The two main categories we compete in are Prototype and UrbanConcept.
The Prototype cars are exceptionally streamlined and designed for maximum fuel efficiency. Here are some pictures of the recently-retired Black Widow, our Prototype car which achieved a best of 2,752.3 miles per gallon on 87 octane gasoline.
The UrbanConcept category places more rigid requirements on the vehicles to be more like an actual small car. They must have 4 doors, a luggage compartment, be seated upright, etc. Our first competitive vehicle in this category is Capax, which achieved 420 miles per gallon (again on 87 octane gasoline).
My role on this vehicle was all the engine wiring, instrumentation, lighting, and telemetry systems. Quite a lot of electronics on this car! We're able to log GPS location, elevation, X/Y/Z forces and angular velocities, and engine data such as spark timing, temperature, manifold air pressure, etc.
This gives the driver a pretty awesome interface. He's got a steering wheel with all the necessary controls right at his fingertips. In addition, he's got a heads-up-display with important speed, engine, and lap timing information to ensure he can have the best performance possible.
And some gibberish about ray tracing?
Mistakes were made and a lot of lessons learned, but a decent chunk of what I gained from this is going into my Masters Thesis work, which looks at a new approach to parallelizing renderers, specifically ray tracers. Hopefully I'll have more pretty pictures to share soon!
"SSD upgrade for iPad 1" için yanıtIt seems unlikely that it would work. The iPad is closer to an embedded device (like a phone) than it is to a general computing device (like a laptop or a desktop computer). Just because the connector is close or the same doesn't mean the signaling protocols that travel over those wires are the right ones to communicate with general PCI-E devices, and for it to talk to an SSD there would need to be hard drive controller of some kind on the other end of the PCI-E bus. Since no iPad model ships with the intention of connecting to SSDs, it seems unlikely Apple would include an unnecessary chip on the logic board. On top of all that, installing OS X on an iPad would be extraordinarily challenging. In particular, the OS is compiled for x86 and x64 processor architectures and the iPad's A4 processor is an ARM chip, so you would most likely need access the full operating system source code to recompile it for the proper architecture. Even if you got that far, there would probably be lots of hardware compatibility...
"What voltage range is permissible for 12v input?" için yanıtAs Phil mentioned, it varies at lot from device to device. However, in general you're always safer if you're supplying the voltage on the "source" side of the power supply. In other words, if you have a device that takes 12V into its power supply, which it presumably steps down into 5V or 3.3V rails, you're probably ok. Most power supplies are designed not only to step down incoming voltage, but also do some power conditioning like smoothing out any fluctuations and preventing against overvoltage or undervoltage damage. If you're shortcutting the power supply and hooking up directly to the main power rails on the device, caveat utilitor. Chips and other components on the other side of the power supply can be much more fickle when it comes to their power requirements, and generally don't have as comprehensive protection against strange power spikes or noisy sources.
"Stuck on bootloader screen" için yanıtIs the operating system stock Android that came with your phone? If you installed a custom ROM, sometimes they can cause your phone to "boot loop" like that. Most of the time using a different kernel will solve the problem. That only applies if you're not using the stock operating system, though.
"Not turning on after chargng, turns hot though." için yanıtIt's quite possible that it could indeed be the battery. According to our teardown the battery is located directly behind the click wheel. I had a similar incident happen to me with a rechargeable battery for my mouse. The lithium ion pack got really hot and swelled up a bit. Does your iPod look swollen on the back at all? The good news is that it's relatively inexpensive to replace the battery for that model. It looks like we have some extra batteries in stock and we've got a guide for replacing the battery. It's not for the faint of heart (you need to do some soldering), but you sound like you can handle it. Good luck!
"Anyway to reattach solder pads?" için yanıtOnce copper solder pads have lifted off the substrate, there's usually no way to get them back on. Your best bet would be to carefully try to scratch off some of the solder mask on top of the traces leading to the missing pads. Once the copper traces are exposed, you should be able to either solder in a short shim wire or blob enough solder to connect the trace with the corresponding pad. If you have a multimeter, you can use its continuity tester function to check the repair and make sure your solder joints are working. Depending on how much of the solder joints are exposed, you may want to add something that will insulate them from other exposed pads to avoid a short. Work carefully, methodically, and slowly, and it should be fixable!
"Logic Board Reflow Question" için yanıtAs the others have mentioned, reflowing the board will only fix bad solder joints, not water damage. Water damage will typically cause shorts which can fry components. Depending on the component, the damage won't always be visible or obvious. If you see a capacitor or resistor that looks dark or warped, that may be a candidate for replacement and be worth a try if your part hunting and soldering skills are up to snuff. But that still won't tell if you if all the complex gates and circuitry inside the larger chips is working properly. With those components, there's really no way to know without sophisticated and expensive equipment and an Electrical Engineering degree. If you don't see anything obvious or the computer still doesn't work after replacing basic components that look damaged, you're probably looking at replacing the entire logic board.