An unloader for discharging and feeding dry, granular type materials from bulk bags. From said signal or signals are derived or calculated at least two parameter values related to a quantity like waveform amplitude, waveform periodicity, waveform morphology, waveform variability, energy, power, signal complexity and frequency content. In one embodiment, this node may be a Vcc terminal. The holder consists of a base having attached a slider sleeve that encloses a candle retaining assembly that includes a candle concentric-gripping mechanism.