Square Reader Tear Down – We’ve taken apart the square credit card reader to show how simple this device really is
You’ve seen them at the local Farmer’s Market, the Bagel Shop, the Art Fair or even at the Girl Scout’s Cookie table – it’s a little white square sticking out of an Android, iPhone or iPad. This little gizmo, with a lot of software behind it, is changing who, and how, credit cards are being used. Please see the related article for more information on the Hip to be Square with Square Credit Card Processing
It’s only an inch tall and half as wide. As electronics go, this is about as simple a device as possible.
One end is a standard 3.5mm headphone mini-jack that plugs into the smart device. The other end contains the magnetic head for reading the strip on a credit card.
Connecting the input reader to the mini-jack are two wires. The entire unit is enclosed in a white clam-shell package. And that’s it for the hardware!
To keep the software as simple as possible, Square’s reader is positioned to read track only the second track on the credit card. This track includes card numbers and expiration dates .
The magnetic stripe consists of 3 physically separated “tracks”. Track 1 is closest to the bottom of the card, and track 3 is at the top. Track 2 is the most commonly used track, but most credit cards also use track 1. Track 1 includes that plus names.
Depending on the particular card, there may be additional data encoded on Track 1. These tracks are about .11 inches wide, so the tolerances in the reader at not that extreme.