Schedule

Schedule

Thursday, July 31

1406826000 Tech News Today
1406829600 Know How...
1406833200 The Social Hour
1406838600 Coding 101
1406842200 Home Theater Geeks
1406847600 Tech News 2Night
1406849400 The Giz Wiz
1406858400 OMGcraft

Friday, August 1

1406912400 Tech News Today
1406916000 This Week in Law
1406923200 Android App Arena
1406934000 Tech News 2Night

Saturday, August 2

1407002400 The Tech Guy

Sunday, August 3

1407088800 The Tech Guy
1407103200 This Week in Tech

Monday, August 4

1407171600 Tech News Today
1407175200 Triangulation
1407180600 iPad Today
1407193200 Tech News 2Night
1407195000 Marketing Mavericks

Tuesday, August 5

1407258000 Tech News Today
1407261600 MacBreak Weekly
1407268800 Security Now
1407276000 Before You Buy
1407279600 Tech News 2Night
1407283200 All About Android

Wednesday, August 6

1407339000 FLOSS Weekly
1407344400 Tech News Today
1407348000 Windows Weekly
1407355200 This Week in Google
1407366000 Tech News 2Night
1407367800 redditUP
1407373200 Ham Nation

Thursday, August 7

1407430800 Tech News Today
1407434400 Know How...
1407438000 The Social Hour
1407443400 Coding 101
1407447000 Home Theater Geeks
1407452400 Tech News 2Night
1407454200 The Giz Wiz
1407463200 OMGcraft

Friday, August 8

1407517200 Tech News Today
1407520800 This Week in Law
1407528000 Android App Arena
1407538800 Tech News 2Night

Saturday, August 9

1407607200 The Tech Guy

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Windows Weekly

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FLOSS Weekly
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Before You Buy

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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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