Beam Break Circuit
The beam break circuit was designed to produce a digital HI output whenever the IR beam between the IR emitter and the IR detector, which were located around 2.5in apart, was broken. To accomplish this, a wide hysteresis band of nearly 1V, centered at 2.5V, was implemented. The output of the comparator would become a digital LO when the input voltage raised above 2.02V and the output would change to a digital HI when the input voltage dropped below 2.98V. When implemented with a debounce timer in software, this circuit reliably indicated to the E128 when a new ball had been loaded from the ball resupply depot.