Make the DODOcase VR / Google Cardboard Switch Work - Samsung Galaxy S3 Phone

The Problem:
I had a chance to try out the DODOcase Virtual Reality Cardboard viewer which is based on the Google Cardboard project. It's a neat, fun, inexpensive way to experience immersive virtual reality. However, I have the Samsung Galaxy 3 and DODOcase VR version 1.1 which explicitly states that the S3 is only partially supported (see this page https://cardboard.withgoogle.com/ "Magnetic input not working").

The Solution:
I managed to get the switch to work for my phone, essentially by moving the magnetic switch to the opposite corner on the VR. I created this instructable in the hopes that it will help others. (Note, DODOcase now provides VR version 1.2 which has a capacitive touch button mechanism which is supposed to work with all devices including iPhone 6 and Android phone)

Parts, Supplies and Tools needed:

• spare cardboard, I used the box the DODOcase VR came in
• tape
• knife - xacto or pocket knife
• pen
• Magnetic field measuring app such as MagnetMeter

Step 1: How Should the Switch Work for My Phone?

The "switch" on the DODOcase VR / Google Cardboard V1.1 consists of a cylindrical magnet on the inside of the viewer and a magnetic ring (which looks like an ordinary washer) on the outside left-hand side of the viewer. When using many of the VR apps, you simply slide the washer down and release it to do things such as select menu options or shoot aliens. How does sliding a little metal washer cause anything to happen in my phone app? Well, one of the sensors on most smartphones is a magnetometer, used to measure the strength of a magnetic field (and normally help with compass direction). Sliding the magnetic ring changes the strength of the magnetic field and that's a signal the phone app can use.

The Hypothesis

Since Google specifically calls out the Samsung Galaxy 3 as not supported for magnetic switch input, I did some searching and found that some people suggest the Magnetometer is on the wrong side in the S3 and perhaps the switch could be moved to the other side to make things work.

The Experimentation

To test things out, I searched google play for a magnetometer app and came up with the app MagnetMeter. This app worked well for what I needed, just a good indication of the strength of the magnetic field when the switch was in the up and down position. The app had a nice setting to avoid sleepmode, but it also seemed to crash occasional. While testing with this app I turned off the NFC setting on my phone to avoid having the DODOcase software start up.

I put the phone in upside down, so my phone's magnetometer would be near the switch. With a little experimentation I found that the sliding the ring does indeed change the strength of the magnetic field, and apps (though sometimes upside down) would now respond to the switch. Theory proved, let's move on to moving the switch

Step 2: Move the Magnetic Switch

To move the switch I simply unfastened the double stick tape holding the magnet side of the VR viewer. I bent this the left side of the viewer down and traced it on a scrap of cardboard (actually as you can see the scrap is the box the DODOcase VR came in). Then I used a pocket knife to cut out the hole and make a piece the correct size to serve as a new layer for the right side of my VR viewer.

I used tape to fasten the magnet and new right hand layer in place (and to refasten the left hand side of the viewer). Once reassembled and with the phone in it's normal position, I found apps such as Google Cardboard and Cardboard Catapult VR app which rely on the magnetic switch now respond correctly. (of course I now have to use my right thumb and slide up instead of my left forefinger sliding down)

Thanks for checking out my Instructable and good luck on all your projects!