DC Motor Kits and Gear Sets for Robots and Models

Fast bare motors against geared TT motors

Two motor types dominate these kits. A bare 130-size DC motor spins very fast, with figures such as 25000 RPM on the box, but delivers little torque at the shaft, which suits fans, propellers and light toys. A TT motor has a plastic gearbox built in, turning around 200 RPM at a ratio such as 1:48, and it gives the pulling force needed to drive wheels on a small robot chassis.

A gear ratio of 1:48 means the motor turns 48 times for each turn of the output shaft: speed drops by that factor and torque rises by roughly the same factor, less friction losses. Gear sets in kits let you build your own reduction, with tooth counts setting the ratio, but check that the module matches between meshing gears and the bore fits the shaft, because gears from different sets often do not mesh cleanly.

What a motor needs besides the motor

A motor kit is not a robot. You still need a power source that fits the voltage range on the label, such as three to six volts for TT motors or three to twelve for 130 motors, and battery holders such as a three-cell AA holder are often sold with the parts. Running a motor at the top of its range gives more speed but more heat and wear.

Control needs more parts. A microcontroller pin cannot supply enough current for a motor, so you need a motor driver or transistor stage and, for reversing, an H-bridge. Add a small capacitor across the motor terminals to tame electrical noise and, with a single-transistor stage, a flyback diode across the motor to absorb switching spikes. Read the included-parts list closely: some kits contain only motors and gears, while others add wire, holders and wheels.

Questions about DC Motor Kits and Gear Sets for Robots and Models

What is the difference between a TT motor and a 130 motor?

A 130 motor is a small bare motor that spins fast with low torque. A TT motor adds a gearbox, so it turns slowly with much more pulling force and is the usual choice for wheels. Choose by whether you need speed or force.

Can I connect a motor straight to a microcontroller board?

No. The board's pins supply only a small current and a motor can draw far more, which can damage the board. Use a motor driver or transistor circuit with its own power supply, and share the ground connection with the controller.

What voltage should I run these motors at?

Stay inside the voltage range printed in the listing. A lower voltage gives slower, quieter running and longer life; the upper end gives more speed with more heat and wear. Keep in mind that battery voltage drops as it discharges, so leave some margin.