Internals of the miniSpinner  

This is a photo of the motor and speed controller used in the miniSpinner. 

The motor is 23mm in diameter and 42 mm long.  It's a German-made coreless rotor 12 volt, 17 watt micromotor.  The shaft rides in two sealed high-precision ball bearings instead of the bronze sleeves used on cheap motors.  This motor is very quiet, durable, highly efficient, and has a remarkable amount of torque for its size.  

Motors like this are commonly used in aeronautical and spacecraft applications like the Mars Rover, high-end medical robots and lab equipment, and that sort of thing.  They are outrageously expensive.  If you wish to buy one from the US distributor, it'll cost you $188 without the sheave (whorl to you spinners).  I make those on my Hardinge CNC lathe.

The speed controller is 1.5 by 2 inches.  This is the almost-final prototype of my latest design using mostly surface mount components, which means the boards can be fabricated by automated machinery.  I assemble prototypes by hand, but the parts are tiny and it takes some practice to solder them successfully.  The smallest parts on this board are 0.120 x 0.060 inches in size.  I will go smaller in the next model of miniSpinner as it'll have to fit much more functionality in about the same amount of space.

I designed this speed controller.  It controls the motor speed using a technique called pulse width modulation (PWM), which in simple terms means switching the power on and off very rapidly at a specific rate and duration.  It is a very efficient way of controlling motor speed, and allows a motor to produce close to its maximum torque at any speed.

This board contains a regulated 5 volt power supply for the PIC microcontroller and associated circuitry, a self-resetting 1.2 amp circuit breaker to protect against short circuits or overloads, and a MOSFET that can handle loads of up to 14 amps at around 55 volts for controlling the motor current.  Overkill, but highly reliable as a result.

The nice thing about using the microcontroller (the 8-pin integrated circuit in the upper left corner of the board) is that it's programmable.  I can easily tailor the behavior of the speed controller by reprogramming the chip.   It also minimizes the number of components which improves reliability.

I really like playing with this kind of stuff.  Always have.