resistors 68 and 69 whose terminal 70 is connected with the base of the transistor 52 and via a capacitor 71 with ground a filter condensor 72 lies between ground and the switch 66 the transistor 52 and its accessory components are made in a suitable manner from epoxy resin this being indicated by the dot dash vertical lines 73 in fig3 when the switch 66 is closed by activating the knob 14 the generator which consists of the crystal 26 and the transistor 52 together with the other elements that form part of the circuit begins to oscillate at a frequency dependent on the dimensions of the crystal 26 but preferably between 60 and 100 khz and more particularly between 100 and 800 khz the crystal 26 modifies its mechanical dimensions in rhythm with the electrical oscillations and these mechanical vibrations are transferred at a magnified amplitude to the tube 12 the point 18 placed over the tube 12 fig1 creates vibrations in a variety of directions as is indicated by the arrows in the foreground of fig5 the vibrations 75 are caused by variations in thickness while the vibrations 76 are the consequence of longitudinal vibrations that move diagonally across the crystal 26 in the form of embodiment shown a y cut crystal is used fig6 shows a quartz crystal 74 against a system of coordinates where 77 and 78 are two possibilities for y cuts in the form of embodiment shown the point 18 thus produces vibrations that are preferably transversal but longitudinal vibrations may also be created with other forms of embodiment or by some other placement of the crystal transversal vibrations are of course preferable for the removal of tartar from teeth for instance for the reasons mentioned in the introduction where.