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andrej stefanovski
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AHN-dray STE-fuh-nawf-skee
AHN-dray STE-fuh-nawf-skee

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Hey all,

I am starting a project which will involve (1) RaspberryPi 3, (1) Arduino Uno R3, and ~150 WS2812B LEDs. These will all be in a box.

I've been trying to figure out power distribution for this box. Generally, I plan to use an external power supply (brick) with a 2.5mm barrel connector. The box will have a female connector and inside power will be split to three devices:

The first will go to the RaspberryPi 3(5V ~2.5A),
The second will go to the Arduino Uno R3 (5V ~1A).
The third will go to the WS2818B's (5V ~9A)

My question is: how to best provide the ~65 Watts of power required at 5V.

The obvious answer (to me) was a power supply that is 5V 15A, and will provide a stable 5V under load. I have been having a hard time finding one that is UL Listed (I feel as though it should be, in term of safety. Please correct me if wrong) and has comments/reviews stating that people are seeing 5V under max load.

I also considered using a 12V 10A brick to the back panel of the box. Inside, I would split power to one 5V 10A and two 5V 3A converter/step down reducers. The devices again shouldn't exceed 65 Watts and the brick would be rated to produce 120 Watts. Total noob so please let me know if I'm missing something.

I'm not sure which of these would be safer for the devices (highest quality of power) as well as safer in general (don't want anything catching fire). Or maybe neither of the above is correct, that's why I'm looking for advice and guidance.

Secondary questions: am I missing something by planning on running the RPi, Arduino and LEDs in parallel off the power supply? I know that in a parallel circuit one path can draw current away from others in the circuit, is there that danger here? If the answer is to use a 5V 15A brick should there be something in line before the boards/LEDs to help stabilize/isolate/clean up (don't know the correct term) the power? I've read that people often place a Capacitor in front of a string of WS2818s, if so what size and what position in the wiring.

I think this project has the chance to be really cool. All three components are currently working, powered separately. I've been playing with the RPi and writing the Arduino code these past few weeks. I'd love to get power distribution figured out so I can move on to the construction of the box :)

Any advice/expertise/best practices are **greatly** appreciated, I want the final product to be the highest quality and safest I can produce.

Thanks!

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Last day to register for the 5K Jennifer is organizing for Chloe Inc

Price: $33.25 USD ($18.25 Stroller Walk, 1 mile)
Date: Saturday, June 25th
Place: Creekside Park and Plaza (Gahanna)

Organization: Chloe Inc. (http://chloeinc.org/about)

501(c)3 so you can probably write that shit off :D

*Registration:* https://runsignup.com/Race/OH/Gahanna/Chloe5K

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Original: https://stefanovski.io/2016/06/last-day-to-register-for-the-5k-jennifer-is-organizing
Chloe 5K
Chloe 5K
runsignup.com
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Troubleshooting Quad Camera Unit for a friend

Hey all, a family friend recently gifted his son a quad copter with a camera unit intended for photo/video capture as well as realtime broadcast to the control unit. They were unable to get a signal from the camera, so they asked me to take a look.

As I detached the Camera Unit from the quad, I noticed the yellow wire coming from the battery/splitter came out of the housing as if it broke off. I disassembled the housing and saw only the Red and Black wires soldered on the board. As soon as I set the unit down on a table the Red and Black wires also broke off. This was an incredibly sloppy job and it does not surprise me that the unit was malfunctioning. I cleaned up the all the excess solder and cleaned the board as best I could before taking photos. Even after cleaning I could not find a reasonable solder point for the yellow (ground, I assume?) wire. The three wires are equal length so I expect a solder point quite close to the other two. I've taken apart a few similar units from friends' quads to see if I can gain any insight but have had no luck (each of those had three clearly labeled points).

I've uploaded two photos (front + back) commented with the initial solder points for the Red/Black wires as well as a clean version of those photos in the best resolution I was able to. Hopefully someone has come across this board, one like it, or has experience and sees what I do not. I'm not positive that the yellow wire was soldered on at all, as it fell out of the housing before I had even managed to remove the screws.

Any help/guidance would be appreciated!

andrej
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3/2/16
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laying fifteen feet from launching fireworks = pretty great

#July4th #IndianLake
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SEM of a migrating cancer cell

Coloured scanning electron micrograph (SEM) of a cultured cancer cell moving (metastasising) through a hole in a support film. Numerous pseudopodia (arm-like), fillipodia (thread-like) and surface blebs (lumps) can be seen. These features are characteristic of highly mobile cells, and enable cancerous cells to spread rapidly around the body, and invade other organs and tissues (metastasis).

Credit: AMI IMAGES/SCIENCE PHOTO LIBRARY
http://www.sciencephoto.com/media/448656/enlarge
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A heartfelt Veterans Day thank you to all who have served. #TeslaVets #VeteransDay 
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2014-11-11
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yup. shut up and take my money.
DNA curious? Here comes your home PCR.

A Boston-based startup, called Amplyus, has invented the miniPCR, a small, relatively cheap do-it-yourself DNA copying kit for homes and schools.

There are three lab testing and analysis kits available: one to test your "DNA Family Tree," one a "Forensic DNA Crime Lab," and one a "DNA Food Safety Lab. The machine also comes with an app, which isn't fully integrated yet and won't read the results of an individual test. What it can do, however, is help set up the experiment and follow what's happening in the machine in real-time. In addition, each user of the app has his or her own interface, so researchers don't have to comb through everyone else's data in order to find their own.

http://goo.gl/5FB5Tv
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Choosing A Secure & Private Messaging System

In case anyone missed it, most of the data and communications we put out into and through the internet these days is being collected. Now, I don't have anything to hide in my communications. That's not the point. I don't have anything to hide when I go the bathroom either but that doesn't mean I want an NSA/Facebook/USSR camera installed in there, either.

So what's the best way for us here in the United States to assert our Constitutional "Right to Privacy" (see: Fourth Amendment, "Right to Privacy" Harvard Law Review (1980)).

The first thing to understand is that the internet is public. You may think this account or that account is private because you use a password to keep people out. There's one problem with that - what happens when you forget your password? The website sends you an email and bam, you have access to your account again. So what, people forget passwords. The issue is, if your data is recoverable then it exists somewhere readable to someone other than only you. That's Public as far as I'm concerned.

The second thing to understand is that email is a Postcard, not a sealed envelope. Anything you send in an email is readable by everyone in the delivery chain. In the analogy of the Post Office, you're relying on the integrity of the mail carrier and the NSA (which takes pictures of every piece of mail that is sent) to not read your Postcard. This is why you don't put personal or sensitive information on a Postcard. When you're talking about the internet, instead of Mail Carriers you're talking about data centers and interconnects all owned by private individuals, companies, and of course governments. Any of those servers can be told to save a copy of all email that comes through there, including attachments. I'm amazed by the sensitive and private information people send (password, social security numbers, credit card numbers, health information) in emails! It's terrifying. So, please don't trust email*.

Truly secure communications are tough. To complicated for most people to bother. That's the point of this. I want to give the people that bother to read this the benefit of my understanding of secure and private communications so they can choose the best method for them. I'll list my advice from general individual to concerned individual to paranoid individual...

https://social.andrejstefanovski.com/2014/choosing-a-secure-private-messaging-system

#Security   #Privacy   #Messaging   #Communication  
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