From the outside we could have guessed how the pin pad worked. With a plastic shell on the outside containing all of the circuitry on the inside, our mental model was: a card is swiped or inserted, the information is taken, the CPU processes the information, sends the information to a bank via USB, SIM card, or ethernet, the CPU displays whether the transaction is successful or not on the display.
Held together by nine screws, pulled apart the pin pad reader and found two very significant things that we learned about ways products are put together.
1. The way the key pad works is strange at a first glance because rubber is not a conductor and it does not create a physical click on the circuit board lying beneath the rubber piece. To the naked eye, the rubber does not contain any metal pieces to create the connection. However, by rubbing the rubber key pad on a piece of paper, it leaves pencil like streaks signifying that the rubber itself contains a graphite like material that can act as a conductor.
2. The second piece we did not understand was a free floating metal cylinder that looked like a button with a rubber ring around one end. When pressed, a metal piece extends past the rubber ring at the end of the cylinder. The "button" cannot be accessed from the outside and lays between the circuit board and a orange board. We also noticed that the battery is soldered to the board. We came to conclusion that because the pin pad carries very precious information, it can be very bad if it is tampered with. So this piece actually acts as a conductor between the orange and green boards but if someone tries to tamper with the pin pad by opening it, the metal recedes back behind the rubber and is no longer conductive. Therefore, it almost acts as a kill switch when people try to open up a pin pad to protect people's credit and debit card information.
Knolling was definitely a fun activity getting to physically see how everyday objects work!
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