Circuit arrangement for a sensor element

Circuit arrangement for at least one sensor element (15) of at least one touch contact switch, in which a control signal (13) with an operating frequency is applied to said sensor element (15) and is variable as a function of the operating state of said sensor element, comprising:

• a signal source (12) for producing said control signal (13), said control signal being an alternating current signal,
• a filter (R1, C1),
• a voltage divider (C1, 15),
• a transistor (T), said control signal (13) being applied across said filter (R1, C1) and said voltage divider (C1, 15) to a base (B) of said transistor,
• a resistor (R2) ensuring a minimum base current at said transistor (T),
• a collector (C) of said transistor (T) is applied across a capacitor (C2) to ground, an output signal (17) at said transistor collector being tappable,
• between said transistor base (B) and ground is connected said the sensor element (15),
• said sensor element is a capacitive sensor element (15).