Abstract: A sensor for sensing the level of adhesive medium in a dispensing device, which sensor comprises; (a) a coil which is adapted to surround a dispensing device for dispensing adhesive medium at an adhesive dispensing station; (b) means for connecting the coil to the input of an oscillator; (c) detector means for detecting the frequency of the output of the coil; (d) conversion means to perform a frequency to voltage conversion on the varying frequency detected at the detector means (c); (e) analogue to digital conversion means to convert the signal from the frequency to voltage conversion means (d) into a form which can be compared with a calibration scale obtained by measuring the signals generated at the output of the coil, when the coil is surrounding a dispensing device containing at least two different known quantities of adhesive medium; and (f) display means for displaying the result of this comparison.