Electrical vibrato and tremolo devices

Claim 1

IN COMBINATION, AN INSTRUMENT FOR PRODUCING ELECTRICAL SIGNALS OF FREQUENCIES CORRESPONDING TO MUSICAL TONES TO BE REPRODUCED; A BRIDGE NETWORK HAVING AN INPUT AND AN OUTPUT; MEANS CONNECTED TO THE INPUT OF SAID BRIDGE NETWORK FOR APPLYING SAID ELECTRICAL SIGNALS TO SAID INPUT; AN AUDIO OUTPUT SYSTEM INCLUDING A LOUDSPEAKER; MEANS COUPLING THE OUTPUT OF SAID BRIDGE NETWORK TO SAID AUDIO OUTPUT SYSTEM IN DRIVING RELATIONSHIP THERETO; AND CONTROL MEANS CONNECTED TO AT LEAST ONE LEG OF SAID BRIDGE NETWORK FOR CYCLICALLY VARYING, AT A CONTROLLED RATE, THE MAGNITUDE OF PHASE SHIFT INTRODUCED BY SAID BRIDGE NETWORK INTO SAID ELECTRICAL SIGNALS, SAID CONTROL MEANS BEING ARRANGED TO VARY THE IMPEDANCE OF AT LEAST ONE ARM OF SAID BRIDGE NETWORK AT SAID CONTROLLED RATE.