hotel switch

It is often required to switch an elec- tric light or apparatus from various positions in a building. A typical example of this is the hotel switch, which makes it possible to control lights from a number of positions. With some electronics and electric wiring, the number of switching pos- itions may be extended ad infinitum. The actual switching is effected by a relay that is controlled by an R-S bistable, N2/N4, via transistors T1and T2. The state of the bistable is of import to the position of logic switches N1and N3. A trigger pulse at the junction of R1and C1is only applied to that input of the bistable which causes the bistable to toggle. In other words, a train of trigger pulses, 0;1;0;1;0..., with a minimum interval between pulses of a few seconds, results in a series of logic level changes which causes the relay to be actuated and de-energized alternately. The trigger pulses arise when one of the push buttons, 51...S n, is pressed briefly. The push buttons are all con- ne...