then increases the output from the power source 22 increasing the power supplied to the motor 28 at a relatively slow rate of speed 2 8 seconds in turn the motor 28 accelerates the inner and outer eccentric weights 50 52 up to speed slowly enough that the slip clutch 60 does not activate and therefore the amplitude does not change at 90 100 of desired speed or at some speed faster than frame resonance the power source 22 suddenly surges to full output for a short period of time 20 milliseconds to 0 5 seconds estimated which causes the clutch 60 to slip and increase the amplitude as the inner and outer eccentric weights 50 52 are moved out of 180 degree opposition note power source 22 output may be larger than what is required to drive the motor 28 at maximum frequency so that the amplitude adjustment can occur at a predetermined speed the controller 80 monitors the response in the vibration of the drum 14 and may also determine the response of the material 12 being compacted via accelerometers 84 mounted on the drum 14 and frame 18 conventional controllers 80 and other hardware such as made by geodynamik for example could be used for this application which is in effect a compaction indicator combined with a compactor control system if the vibration sensed is not adequate for compaction the amplitude is changed until the desired amplitude is reached this is sensed by identifying the point amplitude at which de coupling of the drum 14 from the surface of the material 12 being compacted occurs and then backing off slightly the entire system can be monitored via the.