Schedule

Schedule

Sunday, September 21

1411322400 The Tech Guy
1411336800 This Week in Tech

Monday, September 22

1411405200 Tech News Today
1411408800 Triangulation
1411414200 iPad Today
1411426800 Tech News 2Night
1411428600 Marketing Mavericks

Tuesday, September 23

1411491600 Tech News Today
1411495200 MacBreak Weekly
1411502400 Security Now
1411509600 Before You Buy
1411513200 Tech News 2Night
1411516800 All About Android
1411525800 Padre's Corner

Wednesday, September 24

1411572600 FLOSS Weekly
1411578000 Tech News Today
1411581600 Windows Weekly
1411588800 This Week in Google
1411599600 Tech News 2Night
1411601400 redditUP
1411606800 Ham Nation

Thursday, September 25

1411664400 Tech News Today
1411668000 Know How...
1411671600 The Social Hour
1411677000 Coding 101
1411680600 Home Theater Geeks
1411686000 Tech News 2Night
1411687800 The Giz Wiz
1411696800 OMGcraft

Friday, September 26

1411750800 Tech News Today
1411754400 This Week in Law
1411761600 Android App Arena
1411772400 Tech News 2Night

Saturday, September 27

1411840800 The Tech Guy

Sunday, September 28

1411927200 The Tech Guy
1411941600 This Week in Tech

Monday, September 29

1412010000 Tech News Today
1412013600 Triangulation
1412019000 iPad Today
1412031600 Tech News 2Night
1412033400 Marketing Mavericks

Tuesday, September 30

1412096400 Tech News Today
1412100000 MacBreak Weekly
1412107200 Security Now
1412114400 Before You Buy
1412118000 Tech News 2Night
1412121600 All About Android
1412130600 Padre's Corner

Wednesday, October 1

1412177400 FLOSS Weekly
1412182800 Tech News Today
1412186400 Windows Weekly

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Episode #13: Material Design September 19th, 2014

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TWiT Live Specials
Episode #207: iPhone 6 Unboxing September 19th, 2014

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The Giz Wiz
Episode #1486: No Potato Rotato September 18th, 2014

Capresso, self centering measuring tape, cut resistant gloves.

Home Theater Geeks
Episode #224: CEDIA 2014 Round-Up September 18th, 2014

Scott, Michael, Mark and Tom recap the CEDIA 2014 expo.

OMGcraft

A brand new multi-genre map from qmagnet and his team.

Know How... 103

NFC Tags, Differentials, and Assembling a Transmission

July 24 2014

Verizon goes symmetrical, what is NFC and how to make your own tags, different types of differentials, and assembling the LunchBox RC car transmission.

Verizon goes Symmetrical
If you're one of the lucky few who has Verizon FIOS, rejoice! You're getting Symmetrical!

What is NFC and Using Tags

NFC stands for "Near Field Communication" and, as the implies, it enables very short range communication between compatible devices.
* This means you'll need at least one device to send a signal, and another to receive the signal.
* NFC is a standard and can be used by a large number of devices, most commonly smart phones, but if you've ever used public transit pre-pay card they also work the same way.-"

NFC is based on RFID
* RFID stands for "Radio-frequency identification" which uses electromagnetic induction to transmit information.

* The most common use in smartphones is the peer-to-peer mode, which allows two NFC-enabled devices to send information, like a photo, webpage, or mp3.
* When in this mode both devices are active when sending data, and in a passive state when receiving."

Passive NFC devices
* Like this tag that i got from Amazon, can send information to other NFC devices without the need for a power source of their own.
* Also being passive means a tag doesn't process any information sent from other sources, and can't connect to other passive tags."

"* The biggest difference between NFC and other ways of sending information using radio waves like Bluetooth or WiFi, is that it can induce a electric current with passive devices as well as send data.
* The QI wireless charging that is based on the same principle"

Next there is the read/write mode
This is a one way data transmission, where the active device, like my smartphone, links up with another device to read information from it.

* For example you can program these tags to perform certain actions. I'm using a app called NFC Tools, if you want to get really nitty gritty you might want to try tasker.

Main benefits of NFC?

* The main one is much lower power consumption, NFC is perfect for passive devices, like these tags as they can operate without the need for a power source.
* Drawbacks are, the range is around just a few inches and NFC has a transfer speed of 424 kilobit per second."
* But NFC has fast connectivity. Without have having to manually pair devices, it takes less than one tenth of a second to establish a connection.
*So if you've ever seem Android Beam or S Beam on Samsung phones, they use NFC to quickly connect and then establish a Bluetooth or WiFi Direct connection to share information between devices.

TEFU: How to use NFC, demonstration video.

Amazon TagsForDroid - 12 NFC Pack

NFC Tools

NFC Tasks

Why do we need a differential?

Why do we need a differential?
Let's consider a real-wheel drive car:
* When the car is going straight, both wheels are rotating at the same rate
* HOWEVER, when the car is turning, the OUTSIDE wheel needs to rotate FASTER than the INSIDE wheel.
* If the two wheels were locked by a solid shaft, turning would be difficult because either the inside wheel would have to spin in place, or the outside wheel would have to slide to catch up with the vehicle.

That's what a differential does. It allows for differential rotation of each individual wheel
* In our video, you can see how a typical planetary gear differential works.
* The power is supplied to a gear that is tied to two smaller gears that engage gears attached to the drive shafts.
* Power can transferred to each shaft at different rates, allowing for the differential rotation speeds.

There are many different types and subtypes of differential, but we're going to look at three:

Open Differential:
* Inexpensive - Simple - Easy to Maintain
* Power is transmitted to the path of least resistance
-- However... because of this, if one wheel loses traction, all the power will go to the wheel that has lost traction.

Limited Slip Differential:
* In a LSD, SOME power will always transmitted to the wheel with the most traction
- This can be accomplished by using brakes on the wheel with the least traction
- You can use a hydraulic system
- You can use a clutch system

Locking Differential: Power is transmitted equally between all wheels.
* For use in rugged terrain when you expect to lose traction.
* It essentially removes the differential - allowing power to be equally distributed between the wheels
* HOWEVER, it also makes it very hard to turn.

Assembling the "Lunch Box" Transmission

* Lets figure out our Ratios

The Driver Ratio (aka "The Spur/Pinion Ratio")
* This is the ratio of teeth on the "Spur" the large gear inside the transmission that receives power from the motor, and the "Pinion" the gear attached to the shaft of the motor, which engages the pinion.

In our case, the stock Lunchbox motor and transmission use a 5:1 Spur Pinion ration
- 50 tooth Spur Gear
- 10 tooth Pinion Gear
** 5/1 gearing means that the spur gear will spin once for every 5 revolutions of the pinion gear.
** A Stock 540 power band is at about 20,000 revolutions a minute (It spins faster with more power, and a 540 maxes out at about 23,000rpm)
** At that power, the Spur gear will turn 4,000 time a minute

The Internal Gear Ratio (aka "Transmission Ratio)
* It's further reduced by the gearing between the Spur Gear and the Differential.

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