an independently rate - adjustable multiple channel controller - transmitter for a nerve stimulator to be used in conjunction with an implanted stimulation pulse output unit includes a rate generating circuit for producing asynchronous trigger signals of independently adjustable rate and width , a transmitting circuit for generating bursts of rf energy at separate frequencies in response to the trigger signals , and a rate control circuit for preventing excitation of the transmitting circuit by more than one trigger signal at a time . in the event that two or more trigger signals coincide at the transmitting circuit , the rate control circuit blocks and delays the latter occurring trigger signals with only minor and insignificant effect on trigger signal rate .