Abstract: A circuit board assembly includes a light receiving surface that is capable of transmitting light through the circuit board. The light receiving surface is part of an opening within which an illumination device such as a light bulb is positioned. A slot or other opening is disposed between the light receiving surface and an area of the circuit board in which illumination is not desired. The slot prevents the transmission of light through the thickness of the circuit board and thereby provides for the blocking of light into areas of the circuit board that it is not desired.

Abstract: To accurately detect the short bursts of distinctive ringing signals within 100 milliseconds, a magnitude comparator produces a binary signal indicative of whether the instantaneous tip-ring voltage exceeds a predetermined magnitude. The binary signal is integrated over a predetermined period of time controlled by a timer. If the time integral is below a first predetermined value, the absence of ringing is detected; if above a second predetermined value, ringing is detected; if in between, the integrating interval is extended until the integral falls outside the two values.