Abstract: A card reader can include a card insertion slot, a conveyor member, a card-reading head, and a pendulum sensor assembly. The card insertion slot can receive a card from a user. The conveyor member can be configured to move the card along a transport path extending at least partially within the card reader. The card-reading head can be positioned along the transport path, directed toward the transport path. The card-reading head can be configured to read data held on a magnetic strip or held on an embedded chip. The pendulum sensor assembly can include a pendulum and a first sensor. The pendulum can extend into the transport path and can be freely-pivotable about a pivot axis. The first sensor can be configured to detect an angular position of the pendulum about the pivot axis.