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1  Community / Products and Services / Re: RFduino: iPhone, Bluetooth 4.0 LE, Arduino Compatible Board! on: March 28, 2013, 06:34:34 pm
The RFduino is loads cheaper than an Arduino with Bluetooth. It contains a Nordic 32 bit ARM Cortex-M0 processor. Any idea how this processor compares with an Arduino UNO or an iPhone performance-wise like for image processing?
2  Using Arduino / Project Guidance / Preamps vs Analog to Digital Converter on: October 03, 2012, 09:43:53 pm
I was reading these threads about seismographs:,56217.0.html.

The stages are: sensor (pendulum, gyroscope, etc) => preamp => analog to digital converter => computer

Why use a preamp as opposed to a 24 bit analog to digital converter like the LTC2400?
3  Using Arduino / Motors, Mechanics, and Power / Re: 5V LiPo - Seems kind of clumsy on: August 24, 2012, 11:12:19 am
I looked a bit more and they have an integrated charger booster:
It needs a header for connecting to breadboard, but they have taken care of the JST connectors! Micro USB though.

Just ordered it. And a plug for SparkFun USPS shipping. It is only like $4. I hate to spend $11 for UPS for a couple of items.
4  Using Arduino / Motors, Mechanics, and Power / Re: 5V LiPo - Seems kind of clumsy on: August 24, 2012, 10:46:11 am
Good thought. I just added some comments at SparkFun. Stuff like missing connectors slows me up a lot. It's more ordering them then the soldering.
5  Using Arduino / Motors, Mechanics, and Power / 5V LiPo - Seems kind of clumsy on: August 24, 2012, 09:39:22 am
It looks like to power a 5V arduino requires:
LiPo battery with JST connector:
5V DC to DC Step Up:

The battery connects to the charger easy enough, connecting the Step Up boards seems very clumsy.
To connect the battery to the Step Up, a JST connector like has to be soldered to the Step Up board:
To connect the Step Up to the Arduino, requires soldering jumper cables to the Step Up board.

I guess this is no big deal, but thought this was fairly common and soldering would not be required.
6  Topics / Robotics / Re: Need idea for Gripper - Robotic Arm on: August 23, 2012, 10:00:55 pm
Here is cardboard crane and gripper:

It is 5' plus, which is kind of crazy for cardboard. I bet a smaller one could lift a bit more.
7  Using Arduino / Motors, Mechanics, and Power / Bot with treads has trouble turning on: August 23, 2012, 09:55:41 pm
Bot has Tamiya Twin motor GearBox Set, L293D and 850 mAh LiPo. This battery:

It seems to go straight ok on the floor or carpet. Turning is a problem, particularly on carpet. If you slow a track down it tends to stall.

The gears seem kind of loose. Is slippage and jamming common? Is it underpowered for turning, particularly when there is good traction? Any ballpark ideas how long before needing a charge and is it okay to run it like 15 minutes straight?
8  Using Arduino / Networking, Protocols, and Devices / Re: 2 Signals + Wifly to iPad on: August 22, 2012, 05:54:08 pm
You should be able to do that on an iPad with its wifi capability. I've used an iPhone to connect to a PC.

I used asyncsocket. Here is an example:

This is medium complex. Probably should start by writing the iPad server and seeing if you can connect from your PC. You need to be a member of Apple's developer program ($99). Stackoverflow can help with the iPad questions.
9  Community / Gigs and Collaborations / Re: Personal Emergency Transmitter on: August 19, 2012, 10:34:11 pm
Is there free GSM for emergencies or would GSM require a cell phone contract?

Here is a watch that could be programmed for this purpose: It requires a smartphone.
10  Using Arduino / Project Guidance / Re: How to get facial recogniction? on: August 19, 2012, 10:16:24 pm
I bet you could use OpenCV to segment a face. Then train a neural network on the faces. This is not an Arduino project.
11  Using Arduino / Project Guidance / Re: VEX and DF RobotShop Rover verse homemade bots on: August 19, 2012, 10:13:05 pm
One big problem I have is not wanting to wait for parts when I have the opportunity to work. Also, my wife does not like me using power tools in the kitchen. But my wife and family were away for the weekend, so the cardboard chasis was largely replaced by HDPE, one battery was replaced by a LiPo battery, and a simple bracket was added for a smartphone. The result is quite suitable for indoor SLAM projects.

It does not compare with the Grasshopper with its 4 wheel independent suspension and large motor. Maybe that will be my next project? I don't want to build from scratch again.
12  Topics / Robotics / Re: Ball detection + driving towards the ball.. on: August 17, 2012, 10:01:37 pm
A smartphone (Android or iPhone) with a camera would be a good choice.

I couldn't figure out why the ball was getting bigger...Then it hit me!
13  Topics / Robotics / Re: Video camera with arduino + image processing. on: August 17, 2012, 09:56:02 pm
Use a smartphone. If you don't have one, ask friends and family for an old one. It does not require phone call capability which is why an old phone is ideal. Smartphones support openCV which you could then play with for hours. I'd also recommend you send the images to a PC for R&D. It is a better practice to work with image processing on a PC with OpenCV, Octave or MatLab. Once you figure out what you are doing, then recode it on a smartphone. OpenCv on a PC is better is because it is funner. You are more likely to get it working and have fun doing it.
14  Using Arduino / Project Guidance / Re: VEX and DF RobotShop Rover verse homemade bots on: August 17, 2012, 09:43:55 pm
R/C kits are a good idea. I had a Tamiya Grasshopper that is much quicker and better made than similarly priced robots. I guess I've been resistent to using toys. I only went with tracks after similarly powered three wheeled robots got stuck climbing from floor to rug.
15  Using Arduino / Project Guidance / VEX and DF RobotShop Rover verse homemade bots on: August 14, 2012, 03:40:23 pm
Any opinion on VEX and DF RobotShop Rover 2 verse homemade bots?

Though I enjoyed building a robot, I've come to the conclusion that my tracked device, which is very similar to a DF RobotShop Rover 2, is a piece of garbage. The tracks derail and it is hard to change the batteries.

I was considering just buying the DF RobotShop Rover 2 with XBee/ethernet option or buy the VEX starter bundle for creating a proper frame. Or maybe its time to buy something better/more expensive? My main interests are machine learning. It is convenient to have a shoe box sized robot that is easy to transport.

DF RobotShop Rover 2:

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