A system and methods that enables virtual social interactions for digital representations through the use of virtual objects. In a bus transmitter, a transmit signal characteristic is adjusted in accordance with a topography dependent parameter. The first and third passages may be in communication with a first pressure source and the second and fourth passages may be selectively in communication with a second pressure source. Delivery of atrial therapy is inhibited if the average atrial rate fails to exceed the average ventricular rate by at least a predetermined factor. The output switch supplies an electrical device, connected electrically in series with the full wave bridge rectifier and the output switch, with a constant average current of sufficient level to maintain the electrical device in a desired operating condition.