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.
The interior of the earth emits natural microspulsations of approximately 10 Hz (Hertz), that is 10 oscillations per second. Lightning creates fields in a frequency range of 10 to 20 KHz (thousands of oscillations per second). At the other end of the spectrum light has become visible with billions of oscillations.