Remote control transmitter

Claim 1

Apparatus for transmitting remote control signals having an alternating sequence of two chronologically successive frequency pulses, the first said pulse having a first, predetermined frequency and the second pulse having a second, manually-selectable frequency, the apparatus comprising: a plurality of manually operable command keys, each key supplying at a respective output a manually-selected command signal upon operation; circuit means having a respective input coupled to each said key output for encoding and supplying on a plurality of outputs the received, manually-selected command signal in logic form; circuit means for generating and supplying at resepective outputs two periodic logic pulse sequences which are the logical inverse of one another; circuit means having a plurality of logic inputs for transmitting a signal having a frequency dependent on the logic signals supplied to said inputs; a plurality of resistance elements; a plurality of diodes; and a matrix of coupling points, each said coupling point being connected by a respective resistance element to a respective encoding circuit means output, by a respective diode of predetermined polarity to one of said pulse generating circuit means outputs, and to a respective input of said transmitting circuit means, the polarity of said diodes being predetermined such that during a first portion of the period of said generating circuit means said diodes are conductive to permit a predetermined logic command signal to be supplied from said generating circuit means outputs through said coupling points to said transmitting circuit means and such that during a second portion of said period said diodes are non-conductive to permit said encoded, manually-selected command signal to be passed through said resistors and said coupling points to said transmitting circuit means.