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Schedule

Sunday, January 25

1422212400 The Tech Guy
1422226800 This Week in Tech

Monday, January 26

1422295200 Tech News Today
1422298800 Triangulation
1422304200 iPad Today
1422316800 Tech News 2Night

Tuesday, January 27

1422381600 Tech News Today
1422385200 MacBreak Weekly
1422392400 Security Now
1422399600 Before You Buy
1422403200 Tech News 2Night
1422406800 All About Android
1422415800 Padre's Corner

Wednesday, January 28

1422462600 FLOSS Weekly
1422468000 Tech News Today
1422471600 Windows Weekly
1422478800 This Week in Google
1422489600 Tech News 2Night
1422491400 Android App Arena
1422496800 Ham Nation

Thursday, January 29

1422554400 Tech News Today
1422558000 Know How...
1422561600 Marketing Mavericks
1422567000 Coding 101
1422570600 Home Theater Geeks
1422576000 Tech News 2Night
1422577800 The Giz Wiz

Friday, January 30

1422640800 Tech News Today
1422644400 This Week in Law
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1422730800 The Tech Guy

Sunday, February 1

1422817200 The Tech Guy
1422831600 This Week in Tech

Monday, February 2

1422900000 Tech News Today
1422903600 Triangulation
1422909000 iPad Today
1422921600 Tech News 2Night

Tuesday, February 3

1422986400 Tech News Today
1422990000 MacBreak Weekly
1422997200 Security Now
1423004400 Before You Buy
1423008000 Tech News 2Night
1423011600 All About Android
1423020600 Padre's Corner

Wednesday, February 4

1423067400 FLOSS Weekly

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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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