Energy probe

The energy probe is a simple block in MaddTech, which can only be placed on top of an accumulator (placing it elsewhere is not possible). The top of the energy probe will emit a redstone signal while the accumulator below it is empty; as soon as you fill the accumulator with a tiny bit of energy, the probe turns off the redstone signal.

An example scenario is if the accumulator takes its energy from a nuclear reactor, and on top of that accumulator is an energy probe, connected using a redstone cable to the reactor's redstone input. This guarantees that when energy is pulled out of the accumulator, it will be immediately refilled, providing a constant, on-demand stream of energy.