Know How... 299

We answer questions from our G+ group! How to balance a quad copter, second monitor recommendations, radio-controlled switch, and how much light is too much for your indoor grow!

Balancing Quads        
-- Mr. ROKnBOK        
"Has the subject of "balancing the quadcopter" been addressed on KnowHow? If so, please point me to that episode. Thanks, KitAs!"        
        
I need a 2nd Monitor!        
-- Daniel Casciato        
"Padre mentioned on Windows Weekly episode 471 that one of his best tech purchases was a portable accessory screen for his laptop. This allowed him to use a dual screen setup on the go. 2 questions... 1) what is this screen? 2) Can it be used with a stylus for digital notes, specifically as an input for OneNote?"        
        
Asus MB169C+    ~$150    
* 15.6"         
* Full HD        
* 1920x1080        
* IPS        
* USB-C ONLY!        
        
Asus MB169V+    ~$190    
* Same Specs        
* No IPS, USB 3.0

Throw a switch with a RC        
-- Wayne Hobbins        
"""I'm trying to figure out a way to close a connection with my RC TX using a spare channel that's not passing any electricity like 5 or 12 volts. I know how to do this with a servo and a mechanical switch, but there must be another way.

I thought that the Turnigy transmitter controlled switch might work, but apparently it needs a voltage on one wire to make the connection. I checked the red wires using a ohm meter and there was no difference when switched on and off.

Any ideas?"   
        
We're using an Arduino!        
* We're going to use the same setup that we used for the Growduino        
* The Arduino will read the PWM value from the receiver, then energizer or de-energize the relay        
        
1. Wire it:        
 - Arduino 5V to the receiver        
 - receiver signal to pin 8 of the arduino        
 - relay ground to ground        
 - relay positive to pin 7 of the arduino        
 - circuit through the relay switch pins        
2. Program it:        
 - Use (pulseIn) to read the receiver data value        
 - Use an if-else to turn on/off the relay        
        
Demo:        
1. Assemble circuit        
2. Display PWM values from Arduino        
3. Show if-else logic    

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