The Step-Up/Step-DownS7V8F5 Buck Voltage Regulator module with output voltage 5V, input voltage range of 2.7-11.8V and a maximum output current of 0.5-1A. Pololu 2123

The Step-Up/Step-DownS7V8A Buck Voltage Regulator module with adjustable output voltage in range of 2.5-8V, input voltage range of 2.7-11.8V and a maximum output current of 0.5-1A. Pololu 2118

DRV8825 Stepper Motor Driver Carrier is a DRV8825 stepper motor driver that allows you to supply a bipolar current of up to 1.5 A per phase, without using a heat sink. The system can be supplied with voltage up to 45V, in the set there is a heat sink. Polol 2133

Linear actuator LACT8P-12V-20 with a 20.3 cm stroke and a 20:1 gear ratio provides a force of 500 N and a feedback signal for precise position control. Integrated limit switches and a worm drive enable reliable operation in automation and control systems.

Elenco AK-510 Motion Detector Kit

Pololu Universal Aluminum Mounting Hub for 1/4â€l Shaft, M3 Holes (2-Pack)

Tiny programmable module featuring Microchip’s PIC18F25K50 microcontroller. It packs a Micro-USB interface and 16 digital input/output pins onto a 1″×0.6″ board and ships preloaded with a USB bootloader, so no external programmer is required. Pololu 3150

The compact (0.4″ × 0.5″) D24V5F15 synchronous buck voltage regulator takes an input voltage of up to 36 V and efficiently reduces it to 15 V while allowing for a maximum output current of 500 mA. Pololu 2847

This compact, inexpensive plastic gearmotor (brushed DC motor with a 120:1 reduction gearbox) is well suited for use in small robots. While intended for operation at 4.5 V, it should run comfortably in the 3 V to 6 V range.

This is a breakout board for ON Semiconductor’s AMIS-30543 microstepping bipolar stepper motor driver, which features SPI-adjustable current limiting, 11 step modes (from full-step through 1/128-step), back-EMF feedback that can be used for stall detection or optional closed-loop control, and over-current and over-temperature protection. 

The A-Star 32U4 Mini LV is a programmable module based on the ATmega32U4 from Atmel. Unlike competing products, it has an onboard switching step-up/step-down regulator that allows it to be powered efficiently from a 2.7 V to 11.8 V supply. Pololu 3103

Black Edition offers adjustable current limiting, over-current and over-temperature protection, and five different microstep resolutions. It operates from 8 V to 35 V and can deliver up to 2 A per coil with sufficient additional cooling. Pololu 2128

Solarbotics GMB28 (GM2/GM8 Gear Motor Bracket, Laser-Cut Steel)

The A-Star 32U4 Mini ULV is a programmable module based on the ATmega32U4 from Atmel. Unlike competing products, it has an onboard switching step-up regulator that allows it to be powered efficiently from a 0.5 V to 5.5 V supply. Pololu 3102

Force-Sensing Resistor - 1.5" Square

This synchronous switching step-down (or buck) regulator takes an input voltage of up to 38 V and efficiently reduces it to 5 V with an available output current of around 9 A.

This discrete MOSFET H-bridge motor driver enables bidirectional control of one high-power DC brushed motor. The small 1.3″ × 0.8″ board supports a wide 6.5 V to 40 V voltage range and is efficient enough to deliver a continuous 21 A without a heat sink.

Encoder for Pololu Wheel 42x19mm

The Step-Down D24V3AHV Buck Voltage Regulator module with adjustable output voltage in the range of 4-25V with a wide input voltage range of 4.5-42V and a maximum output current of 300 mA. Pololu 2102