Schedule

Schedule

Friday, August 29

1409331600 Tech News Today
1409335200 This Week in Law
1409342400 Android App Arena
1409353200 Tech News 2Night

Saturday, August 30

1409421600 The Tech Guy

Sunday, August 31

1409508000 The Tech Guy
1409522400 This Week in Tech

Monday, September 1

1409590800 Tech News Today
1409594400 Triangulation
1409599800 iPad Today
1409612400 Tech News 2Night
1409614200 Marketing Mavericks

Tuesday, September 2

1409677200 Tech News Today
1409680800 MacBreak Weekly
1409688000 Security Now
1409695200 Before You Buy
1409698800 Tech News 2Night
1409702400 All About Android
1409711400 Padre's Corner

Wednesday, September 3

1409758200 FLOSS Weekly
1409763600 Tech News Today
1409767200 Windows Weekly
1409774400 This Week in Google
1409785200 Tech News 2Night
1409787000 redditUP
1409792400 Ham Nation

Thursday, September 4

1409850000 Tech News Today
1409853600 Know How...
1409857200 The Social Hour
1409862600 Coding 101
1409866200 Home Theater Geeks
1409871600 Tech News 2Night
1409873400 The Giz Wiz
1409882400 OMGcraft

Friday, September 5

1409936400 Tech News Today
1409940000 This Week in Law
1409947200 Android App Arena
1409958000 Tech News 2Night

Saturday, September 6

1410026400 The Tech Guy

Sunday, September 7

1410112800 The Tech Guy
1410127200 This Week in Tech

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Home Theater Geeks

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Tech News 2Night

Apple announces Sept. 9th event.

Know How...

Lunchbox with braiiiiiiins!

The Giz Wiz

GoGo Pillow, PackIt, Keurig Mini.

Coding 101

This week we're going abstract.

The Social Hour

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OMGcraft

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FLOSS Weekly
Episode #306: RStudio August 28th, 2014

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Tech News Today

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Know How... 91

F1 Turbo, Solar Powered Rasp Pi, and Goat Sim Tips

May 1 2014

Mercedes is wining F1 with a new twist on an old technology, power your Raspberry Pi with the sun, and Goat Simulator Tips.

Solar 101: Solar-Powered Pi

Materials:
Solar Panels
Charge Controller
Battery
12v to 5v (USB Charger)

Tools:
Wire Snips
Wire Strippers
Screwdrivers
Multimeter

Steps:
1. Determine the Draw of your Device(s)
2. Size your Battery
3. Calculate your Solar Panel Needs
4. Choose your Controller
5. Wire it!

The Draw of your Devices:
* If you're building for a house, you can look at your electricity bill for the past 12 months. That gives you a good indication of your total usage as well as your high and low usage months.
* For medium-applications, a Kill-O-Watt works well, but it has a large margin for error, especially when dealing with smaller devices
* If you're building for a small device, check the specs of the device(s) you want to power.
- A spec sheet is a good place to start
- Remember that you must also account for the inefficiency of any charging unit

A Raspberry Pie pulls 700 mA of current at 5 volts at maximum power. (It pulls 300mA at idle)

Watts = Volts * Amps
- W=VA
- West Virginia

That means the RasPi draws 700mA at 5volts, or 3.5 Watt/Hours at maximum load.
** We need to supply the RasPi with 84 Watt/Hours of power per day.

Size your Battery
You need a battery that will support your application.
* Your typically want a battery that can support your device(s) for an acceptable amount of time, assuming that there will be days when your solar panels are completely ineffective.
* For an application like the Raspberry Pi, since it doesn't draw that much, I wanted to design a system that could go 2 days without ANY solar power input.
- Since the daily draw of a RasPi is a maximum of 84 Watt/Hours a day, I need at least 168 Watt/Hours of storage.
* Most small-application solar charge regulators work at 12 or 24 volts. I chose 2 x 12v 8Ah battery that will give me 192 Watt/Hours of storage

Make SURE to get a deep-cycle battery. If you don't you'll quickly find that your batteries don't provide their rated power because of the memory effect. (Most batteries are NOT designed to run all the way down.

Calculate your Solar Panel Needs:
You need to know (1. Draw of your devices) and (2. PEAK Hours in your Location)

Peak Sun Hours is the equivalent number of hours per day when solar irradiance averages 1,000watts per square meter.
- You want to know the amount of sun energy you'll receive per day on the WORST MONTHS of the year.
- Included is a "worst case scenario" solar map based on data from the past 30 years.

* You can use this information to determine how much panel you need.
* In our example. We know that our draw will be 84 Watt/Hours a day
- We need a panel that can generate 84 Watt/Hours a day with MY Peak Hour value
- We also need to keep in mind the charging of the battery. The more power OVER than number, the faster I'll charge a depleted battery.
- I also like to give myself a margin of safety to account for inefficiencies. (I use 20%)

In my location in San Francisco, the worst-case Peak Sun value is 3.6
- That means I can expect MAXIMUM solar exposure for a minimum of 3.6 hours a day
- I have two 90Wh batteries to fill and 84Wh of draw, but only 12.6 Watt/hours of that draw (3.6 hours x 3.5 Watts/hour) will come from the solar panel, the rest will come from the battery.
- I also want to account for the inefficiencies of the system. (I'll add in another 40W/h)
- That means I want a Solar Array that can give me ~240W/H in those 3.6 hours of Peak Sun.

I actually have a 240W/H solar panel… which means I am WAY over supplying the Pi!

Choose your Solar Charger
- You need a unit that will support the total wattage of your Solar Panels AND the total draw of your electronic devices.

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