An exemplary air cushion inflation machine includes: a first terminal connected to a direct current input; a second terminal; a reference resistor powered by the direct current input; an op-amp; and a transistor. The first terminal of the op-amp is connected to a variable voltage source and the second terminal of the op-amp is connected to the reference resistor. The transistor has a base connected to an output of the op-amp, an emitter connected to the reference resistor, and a collector connected to a first terminal of a sealing band apparatus having first and second terminals. A meltable material placed between the first and second terminals is melted by resistance of current flowing between the first and second terminals. The variable voltage source changes voltage based on a voltage drop measured across the first and second terminals by a voltage measurement device and the constant current.