4. Distinguishing the QTR-8A from the QTR-8RC

The QTR-8A sensor array has a different output format from the QTR-8RC, so it is important you know which sensor model you have. What distinguishes one model from another are the components placed on a common PCB. The pictures below show the two models:

QTR-8A reflectance sensor array.

QTR-8RC reflectance sensor array.

The QTR-8A uses a voltage divider for each sensor’s output while the QTR-8RC uses an RC circuit. This produces the most visible difference between the two: eight 47k voltage divider resistors (black components with “473” written on them in yellow) on the QTR-8A are replaced by capacitors (tan components) on the QTR-8RC.