The invention relates to radio-control of lifting machinery, and is intended to solve problems due to the presence of interfering metal masses. The clock signal control circuitry is for receiving a clock signal from a clock signal generator and for outputting said clock signal to synchronous circuitry that is to be clocked by said clock signal. In some embodiments of the invention, the high-voltage power supply is arranged on a top layer while the transmitter and receiver are arranged on a bottom layer in a split-ground arrangement. A subsequent decoupling of the outputs allows cross-coupling within the interface circuit to latch the outputs to a logical state corresponding to the stored magnetic state, thereby allowing the stored state of a cell to be read.