Abstract: A capacitance probe extends into a container for material which increases the capacitance between the probe and the container when the material contacts the probe. A fixed RF voltage is supplied to the base of a transistor in an electronic translator having a capacitor between the probe and the transistor's emitter. A first diode conducts between the base and RF ground. A second diode conducts between the emitter and the base. A small-value capacitor is connected between an ungrounded DC supply terminal and the probe. A third diode conducts variable DC to the transistor's collector from a variable DC signal line supplied with DC for the DC terminal through a resistor. A comparator has a first input connected to the line and a second input connected to a reference voltage. The comparator's output is adapted to energize an output signal and a relay when the DC signal on the line drops below the reference voltage.