Demons can smell like sulfur, roses, cologne...anything! They can also appear as: an angel of light, a dead person or child, a spirit guide, a healing spirit (reiki), an alien, a fairy, a dwarf, a spirit animal etc! We can't safely discern them! The safest thing to do, is let Jesus and his angels protect us.
The recommendation is therefore that the stimulation should be applied with a 2500Hz carrier medium frequency sinusoidal alternating current, burst at 50 Hz (10ms ON: 10ms OFF) at a maximum tolerable level.
Twice the highest modulating frequency. In AM radio broadcasting, the modulating signal has bandwidth of 15kHz, and hence the bandwidth of an amplitude-modulated signal is 30kHz. Twice the sum of the modulating signal frequency and the frequency deviation.