Schedule

Schedule

Thursday, April 2

1427994000 Tech News Today
1427997600 Know How...
1428003000 Marketing Mavericks
1428008400 Home Theater Geeks
1428015600 Tech News 2Night
1428017400 The Giz Wiz

Friday, April 3

1428080400 Tech News Today
1428084000 This Week in Law
1428094800 Before You Buy
1428102000 Tech News 2Night
1428105600 Padre's Corner

Saturday, April 4

1428170400 The Tech Guy

Sunday, April 5

1428256800 The Tech Guy
1428271200 This Week in Tech

Monday, April 6

1428339600 Tech News Today
1428343200 Triangulation
1428348600 iPad Today
1428355800 Coding 101
1428361200 Tech News 2Night

Tuesday, April 7

1428426000 Tech News Today
1428429600 MacBreak Weekly
1428438600 Security Now
1428447600 Tech News 2Night
1428451200 All About Android

Wednesday, April 8

1428507000 FLOSS Weekly
1428512400 Tech News Today
1428516000 Windows Weekly
1428523200 This Week in Google
1428534000 Tech News 2Night
1428535800 Android App Arena
1428541200 Ham Nation

Thursday, April 9

1428598800 Tech News Today
1428602400 Know How...
1428607800 Marketing Mavericks
1428613200 Home Theater Geeks
1428620400 Tech News 2Night
1428622200 The Giz Wiz

Friday, April 10

1428685200 Tech News Today
1428688800 This Week in Law
1428699600 Before You Buy
1428706800 Tech News 2Night
1428710400 Padre's Corner

Saturday, April 11

1428775200 The Tech Guy

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Ham Nation

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This Week in Google

Summary of April Fools Stuff

Android App Arena

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Tech News 2Night

Show Me You're Fridge on Periscope!

iFive for the iPhone

Megan has the prototype of the new iPhone 6S JK!

FLOSS Weekly
Episode #330: Docker April 1st, 2015

Solomon Hykes and Docker has it's 2nd birthday.

Tech News Today

1200 Radio Shack stores may stay open with more Sprint products.

All About Android

Samsung Galaxy S6, The Chrome Stick, and Android Apps on Chrome OS!

Security Now

Is it possible to replace a crashed hard drive when UEFI secure boot is on?

Tech News 2Night

Microsoft Surface 3 can run Windows 10.

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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