switching function of triac switch 56 effective through bus 67 for control of the fiberizer valve solenoids illustrated for four fiberizer positions of the glass fiber mat producing system the main bus 65 is coupled to the parallel connected solenoids for each fiberizer position as typified by solenoids of fig3 representing as viewed in the collection screen direction of advance right side valve control at solenoids 35 and 37 and left side valve control at solenoids 36 and 38 for fiberizer units 11 and 18 of fiberizer positions 1 and 2 similar right side and left side nozzles for fiberizer positions 3 and 4 are controlled valve solenoids 68 and 69 and 71 and 72 respectively the parallel connection of each fiberizer position solenoid pair behind a selector switch 73 74 75 and 76 insures that the valves for each side of each position operate simultaneously an operator is kept informed of the state of operation 34 on 34 or 34 off 34 of the air lapper for each fiberizer position by an indicator lamp 78 79 81 and 82 connected in parallel with the solenoids and behind the respective control switches for operator convenience the indicators 78 82 and control switches 73 76 for individual fiberizer positions can be located on the control panel with master switch 63 master indicator 66 and frequency control 52 and duty cycle control 53 switch 56 is controlled from leads 91 and.