Abstract: An image/message display device includes a ceiling fan suspended from the ceiling. A controller for the display is mounted on the ceiling fan and includes hall effect sensors for determining the rotational speed of the fan. LED panels are mounted on each of the blades for creating the image/message as the ceiling fan turns. Aerodynamic covers are placed over the LED panels. A dark, non-reflective background may be suspended behind the LED panels to enhance the view of the image/display.

Abstract: A two-telephone intercom has a simple station-call signalling system. In the preferred embodiment, each telephone is provided with its own respective signalling unit comprising (a) a dc voltage source, (b) a voltage-sensitive threshold element (preferably, a zener diode), and (c) a signalling device, e.g., a beeper and/or flashing light. Whenever one of the telephones is activated (i.e., taken off hook), the signalling device associated with the other telephone becomes operative and remains operative until the other telephone is answered (i.e., activated) or until the first telephone is hung up. Three embodiments of the signalling-unit circuits are disclosed.