The Model 330 bench top tester presents three different levels of inductance change to inductive loop detectors based on the NEMA TS1, NEMA TS2, and FHWA/ CalTrans 1989 standards. The tester can test 1 & 2 channel shelf-type detectors, 2 & 4 channel racktype detectors, and CALTRANS/FHWA Model 222 and Model 224 are supported as well. The tester provides the appropriate power to the detector and the three fixed levels of input signal to each detection channel of the detector. The output (call) status of the detector channel shall be monitored by the tester with a visual indicator (LED). The tester includes a reset push button to reset the detector after the operator makes any sensitivity adjustments while the detector is under power. Three fixed levels provided to the input pins of the detector correspond to the NEMA-specified inductance changes (Delta L/L) defined to represent a small motorcycle (0.13%), a large motorcycle, (0.32%), and a passenger car (3.2%).