Motors

Frequency is how many times per second the surface moves. Amplitude is how far it moves each time. High frequency with small amplitude spreads energy across the surface and saturates the fast adapting receptors in skin, which is the physical basis of going numb. Lower frequency with larger amplitude reaches deeper structures and adapts more slowly, which is why a rumbly object stays interesting longer.

Without a specification sheet, weight is the most reliable clue available in a shop. A larger motor with more torque needs a larger magnet and a heavier rotor, and torque is what keeps a motor at its intended speed when tissue loads it. A very light object with an impressive display setting is almost always using a small eccentric mass at high speed.

Dual motor designs complicate this usefully. Two motors placed at different points can run at different speeds, which produces interference patterns that neither motor makes alone. It also doubles the drain on the battery, which is where the battery page becomes relevant.

Anyone who has found vibration numbing rather than intense is usually reacting to frequency, and a rumbly motor changes that experience entirely. Anyone who finds deep vibration too diffuse often prefers the sharper, more localised feel of a high frequency design. Both preferences are common and stable, which makes mechanism the first filter worth applying.

Retail categories rarely sort by motor type, so the practical route is to sort by product type and then read specifications. Ranges such as the inWonderstate listings state motor detail and weight on the product page, which is enough to work out the mechanism before ordering.

Motors are usually the last thing to fail. Batteries lose capacity, charging contacts corrode, seals harden, buttons stop registering. A motor that has been kept dry and not run at maximum against a hard surface for hours will outlast the cell driving it, which is covered in the retirement page.