Freeside Atlanta

We've had two really great 3D printing meetups lately, one to talk about and demo 3D printers , and another to help people build and debug them . Here's some of the stuff we saw -   Jorge brought in his Rostock Prisma to show it off and debug a few extruder issues. It's a really cool and fairly robust design. Plus, it's a lot of fun to watch! You can also check out the Thingyverse page that Jorge has put together for it.  We also had Ant's 3D printer and the Thing-o-Matic going, so people could benchmark or run off a few parts. James Stephens also brought in his RepRap Mendel to debug some extruder issues. Randy did some work on his CNC, building a cabinet with removable side-walls for it, while Van continued working on his 3D Printer, the same variant as Ant's and the one that I am building for the space. I made slow progress on that, too, and it "only needs to be wired up" now. That's all for now! Watch our Me...

I got an interesting question on my YouTube channel yesterday asking if my transimpendance ammeter can measure A/C in addition to D/C and if the output of the instrument is A/C. The answer is yes to all of the above. Good question and a fun little thing to test on the bench on a Saturday morning.

I pushed 185 watts through my custom DC relays last night. They ate up that power like a champ. Likewise, I've also been testing it in the off condition to measure its steady off power consumption. The cards burn 150 nano amps or 1.8uW when off. That's means it's about 80 mega ohms which is OUTSTANDING. This project is really moving along nicely. I have some serious burn in testing to do and then it's time to get the main board encapsulated and do some real life testing. That's going to be fun!

Well, its time to finally get this project "out there". I've been sitting on it for months putting together a bunch of cool little projects for this board and the video above shows off some of the cooler ones. Check out the Kickstarter page for more details as well. Ever since I saw Kickstarter the first time I've been wanting to give this a shot so I could learn the ins and outs of doing small scale manufacturing from home. Because this is not a product, but a platform or hacker tool I am not super confident there is a substantial enough market for it but I cannot know if I don't try. The plan if this succeeds is to give all the boards a final value engineering assessment and put the project out to bid. I've already done this with a Florida shop called Tropical Assemblies as well as with Seeedstudio. I'm not super excited with Seeeds PCB quality so I think I'll skip them but the good news is that the local fab shop had similar prices so at l...

Recently, we at Freeside Atlanta teamed up with the Alchemical Arts Alliance and My Inventor Club to design and build an Offroad Wheelchair so that our friend Robin can get around their events. Together, we've raised about $2,000 for the project. The design phase is usually the most difficult part of the projects, and it is often the most expensive place to make a mistake. Committing the resources to a poorly-designed project can cause the entire thing to be wasted, so we designed the Offroad Wheelchair project very carefully. We started with the constraints – We need ease of maneuverability, an ability to overcome obstacles and take fairly steep inclines, longevity to make it through events up to a week long, and recoverability in case it gets stuck. Also, biggest two constraints – Budget (~$2000) and time to prototype (2 months) From that, we landed on 3 design options – 1 – Electric motors with onboard generator for periodic battery charge 2 – Modifying an exi...

If you've been following along on my journey to learn electronics design, you'll know I've been working on a motorcycle power supply. It's getting pretty close to finished and its time to do testing. The last series of blogs were about a constant current load testing device. I needed that to test the power supply under different load conditions. This installment is about the opposite end of that spectrum, what happens when the circuit is "off". Because lots of motorcycles tend to be parked for months without being ridden I need to verify that my device does not contribute to early battery failure. To do that I need to measure the current consumed when it is plugged in but off. We are talking about very small currents though so very high precision measurements are required. Normally, you can use a digital multimeter for this purpose but for measuring small currents this not as straightforward as it seems. Ammeters are connected in series with a circuit an...

The project is finished. The units have been built and sent off for use. Much was learned. Here are some insights. First, don't design a PCB for the lowest cost. That just increases your costs later. I made the the board narrower than was convenient to save $20 and I ended up wanting to put the entire thing a case so I could mount the banana adapters off the PCB where they could be farther apart. Not necessary but preferred for me. Second, putting artwork in copper on your PCB not only works but looks great when you are finished. Take a look at the second photo below. That Freeside logo looks awesome! Third, assembly of through hole components is NOT easier than surface mount parts. It was a bit of a pain to build them all. TH components don't stay in place when you flip it over to solder.  Final PCB I used. Artwork in copper. Queued up for soldering. Delivered and installed. My lab's version with voltmeter and case. It includes a cooling...

Greetings fellow Raspberry Pi enthusiasts. I have something pretty cool to share with you today. I've been wanting to use the Raspberry Pi for a media center since I first heard about it. When Newark finally told me I could order the Pi I jumped at it chance and then promptly left town on a family vacation. My nephew Isaiah, who I met up with in Alaska while we were on vacation, discussed the media center project and how to implement it. Upon his suggestion we settled on running VLC. I had assumed we would have to get some webserver up and running and figure out how to slave VLC to our wishes but that is largely built in already. It is called the VLC Web Interface (or VLC http interface). That made this project all the more simple. Below is the process to install it. This process assumes you have a freshly flashed Raspbian Wheezy (7/15) image that has NEVER BEEN BOOTED BEFORE. This made the most sense for us as we assumed you would plop this guy down somewhere and not use it ...

I've been working on an Arduino compatible Mini USB Host board. Well, I've had it done for a while now. I've slowly been compiling a bunch of projects for it so I can give it a cool Kickstarter one of these days. To that end, I designed a dedicated shield for controlling a Roomba vacuum with a Wii remote controller so that it might make the entirety of the project more compelling. I'd already written the firmware and tested it with a chopped and spliced up cable a few months ago. It worked well for a while but one day the entire thing shot craps. My belief is that the on board voltage regulators could not handle the 16V the Roomba outputs (too much voltage to drop with an LDO without good cooling). So, for the dedicated board I decided to put a TO-220 7805 regulator with a heatsink on it. That should protect the main board from damage. I also had the idea of using optocouplers to isolate the Roomba signals from the shield. Optocouplers are ICs that contain an inte...

It's been a difficult journey, but we finally got the first flight of our DIY Drones Hexacopter . A special thank you goes out to the whole UAV team at Freeside Atlanta for donating their time, money, and resources to this project.  Slade, who did several hours of last-mile troubleshooting to get the UAV in the air, is flying it by hand. Check out the video on Youtube , which shows us testing the pitch, yaw, and roll of the unit and finally getting flight. We were pretty surprised at how smoothly it flies. Stay tuned, as we'll be setting up and configuring the UAV controls so that it can follow GPS waypoint flight paths. We're also going to be posting another video that explains how everything works, how we did the troubleshooting on the initial flight, and some new in-flight footage.

Since the last installment, I've finalized the initial PCB design and sent it off to Seeedstudio  for fabrication. I've never designed a through-hole (TH) construction board before but in general all the same rules apply to SMD and TH boards I believe. 200W 0.1Ω load   30W 1Ω load 10x10Ω 3W in || 25 turn trimmer pot I changed up a few things during the PCB design phase of this project that I thought would be interesting to mention. I added a pair of trim pots to design. One trim pot reduces the maximum voltage going into the first op-amp stage. The second is the in the feedback loop of the first op amp stage. At maximum resistance, 3000Ω to GND (R2 of the voltage divider), with the 820Ω R1 (there for its role as a low pass filter in addition to the voltage divider), I should see a 27% voltage gain. Turned down to 0Ω, that pot creates a situation where the output is the high output voltage of the op-amp (essentially infinite gain). Something like 8V for ...

While working on the constant current load project I found that while nice, the multiple turns required to turn up the power up was a little annoying when you just wanted to hurry up and get to a high value. The standard solution is to have a "fine" and "course" knob. Since I designed the input in the digital realm it seemed like software was the obvious solution. Why not sense the speed the user is turning the knob and extrapolate the pace of change based on that input. It seems intuitive to me. I implemented it as a little C++ library that you can drop into your arduino/libraries directory. Here is the most trivial implementation of the library. #include <RotaryEncoder.h>; RotaryEncoder encoder(A0,A1,5,6,1000); void setup() { Serial.begin(57600); } void loop() { int enc = encoder.readEncoder(); if(enc != 0) { Serial.println(enc); } delayMicroseconds(5); } Inside the library, the code counts the number of the sequential clicks in one...

The Off-Road Wheelchair is a device that will enable a person of limited mobility to experience the outdoors. Freeside Atlanta is interested in putting our engineering skills to the test, and showing the world we can create anything we put our minds to. We have the space, the tools, and the talented people to make this happen - we just need your help to purchase the materials and make this project a reality. The idea originated with Robin Beattie, who participates in regional Burning Man events, like the Alchemy Arts Festival here in Georgia. The festival takes place on a farm, with terrain features like gravel, light mud, paths with tree roots, and moderate changes in elevation. The Off-Road Wheelchair will be designed to traverse this environment, enabling Robin to get around in a place that would normally be closed off to her and others with limited mobility. Upon completion, the Off-Road Wheelchair designs and notes will be released under a Creative Commons (by-nc) license, w...

I just got my first oscilloscope. Complex analog circuits are now possible. As I mentioned in my last post, I working on a power distribution unit (PDU) for motorcycles, cars, and other DC applications. The project is very close to the testing phase and that means I will need to run this device at precise power levels and at precise temperatures. The testing protocol also includes vibration studies, but today we are just going to talk about precision current testing. This can be done many different ways. You can just put a resistor to ground and use Ohm's Law to tell you how much current you are burning. If you want to change the current in use though, you will have to change the resistor. That is not very handy if you want to test your power supply at multiple currents as you will need a lot of different resistors. Since my system is running at about 14V and I am talking about 15A of current, I'll need some pretty beefy resistors and those are expensive. Instead...