DC 220V 350W/680W High-Power High-Speed Variable-Speed Motor DIY Motor. The motor requires the included rectifier bridge to operate on 220V AC power. Never connect it directly to 220V AC power!!! This is a carbon brush motor with a no-load speed of approximately 7000 RPM, with a tolerance of 5-8%. It supports forward/reverse operation and speed adjustment. Lowering the speed reduces torque accordingly. 0W motor incorporates an internal cooling fan, enabling extended operation (limit to 1-2 hours based on load intensity)! If you need to drill large holes or drill into metal, you must modify the tool with a non-powered spindle; direct use is prohibited, and we assume no responsibility for burnout. Issues arising when using a speed controller. Motor power and torque decrease as speed drops. Some motors may exhibit vibration; adding a filter capacitor may help, though it won’t eliminate the issue entirely. To reduce speed without sacrificing torque, use a synchronous pulley and belt. Note this setup provides only one fixed output speed. Alternatively, combine a synchronous pulley with a speed controller for speed reduction. Critical Precautions for Reversing Direction with Speed Controllers: Always follow this sequence: Forward? Stop? Reverse. NEVER attempt direct forward-to-reverse switching. This will burn out the motor and is extremely dangerous!