Using your Android as a second Windows monitor: fast refresh rate + free solution

Ver. 1.6

Do you know that you probably carry a PC monitor in your pocket or backpack?

You may have heard of Android terminal clients connecting to a Windows (Unix, Mac, etc.) desktop server: the most popular are Microsoft Remote Desktop Client  2X Client, VNC, Teamviewer.

Yet do you know that you can connect your Android device (tablet or phone etc.) to the current Windows session so that it is treated as a second monitor?

This is what it looks like in Windows:

and the actual hardware setup:

To enable it, you need any Android (preferably rooted) device, a USB cable connecting the Android device to your PC and Windows 7 or lower (sic!) operating system on the PC.

There are paid applications that do it, but after some modding, we can get the same (or even better) results for free.

Get this modded installation package from here or from here
* [2015-11-01 See important update below]

It uses AirScreen, and Mirage video driver (no need to install these, they are included already):

Install the Airscreen PC server (version 2.6) on your Windows PC. (Do not run it yet.)

Delete the installation directory (C:\Program Files\Quickturn\AirScreen) and overwrite it with the patch from the package.

Check if the Mirage mirror video driver was correctly installed as a virtual display adapter:

(This driver is key to the trick. Alas, it will not work in Windows 8.)

Install a VNC viewer (take your pick, I prefer AndroidVNC) in your Android device or use the default AirScreen client app (not recommended).

Connect your Android device with the PC via the USB cable. 

Enable USB Tethering on Android. (You may want to install the CM-AutoTether.apk to automate it if your device is rooted.)

Make sure that your PC discovered your Android device and the right drivers have been installed. (The ADB daemon running is not needed here in fact, just the tethering driver.) 

Find your tethered PC client's IP for the USB connection: use ipconfig or hover over the AirScreen server in the tray to display the IPs.

 

Your IP will probably be within the 192.168.42.* range.

You may check the connectivity to PC from Android - use the IP Tools, ping or a similar package.

Detect and enable dual monitor in the PC's Control Panel. 

The "Display device on: VGA" is in fact your virtual mirror Mirage driver.

Connect your VNC viewer to http://[your-pc-ip]:7654

Tips:

Install the fullscreen mode root application.

Remap the control key: Left hold -> Android Menu. 

Install the AutoTether app

Install Rotate Display (or similar), rotate to Reverse Portrait, and rotate to Portrait on the PC. Then physically rotate your Android counterclockwise.

Check this animated gif on your new Android monitor window, to test the refresh rate:

(Click to enlarge in full screeen)

Caveats:

• Create system restore points or backups, to roll back if needed. You have been warned.
• When playing with it, do not change the main monitor to the AirScreen Android virtual one! Windows will mess things up, even upon reboot. If you get lost, to restore: either drag the control panel window by Alt+Space, M, and arrows to the visible area, or restore Windows to the previous state by e.g. the system restore point.
• Use the Windows key+P combination to switch the monitors, if you cannot see your the display control window on the PC.  

Enjoy!

Refresh rate test:

Update 1:
Thank you for alerting me about virus alert when downloading the package from Google Drive. I have not changed the zip file since uploading it, but virus signatures may have been updated since then.

I checked these with online scanner now. Here are the results ->  One match for: adware-eorezo-374
I will add a second download link, with a caveat emptor notice.

Update 2: 
Use free SCRCPY for fast mirroring Android on your PC, also via WiFi.