Power adapter with ATX computer connector and banana sockets with 3.3 V, 5 V, +12 V and -12 V voltage outputs. Mounting kit. SparkFun KIT-12867

Step-Up/Step-Down converter module based on the S13V30F5 system, input voltage from 2.8 to 22 V, output voltage 5 V. Current efficiency of the converter 4 A. Pololu 4082

DC-DC Step-Up converter U3V40F5 with an output voltage of 5 V, an input voltage of 1.3 to 5 V and a maximum output current of 4 A. Pololu 4012

Step-Down converter D36V28F9 with an output voltage of 9 V, an input voltage from 9.8 to 50 V and a maximum output current of 3.4 A. Pololu 3785

Step-Down converter D36V28F6 with an output voltage of 6 V, an input voltage from 6.3 to 50 V and a maximum output current of 4 A. Pololu 3783

Step-Down converter D36V28F3 with an output voltage of 3.3 V, an input voltage from 4.5 to 50 V and a maximum output current of 4.5 A. Pololu 3781

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

Power supply module with an input voltage from 4 to 9 V and a configurable output voltage of 3.3 V or 1.8 V. It has holes with a 2.54 mm pitch. Perfect for use with a contact plate. SparkFun PRT-13157

Step-Down converter D36V50F3 with an output voltage of 3.3 V, an input voltage from 4.5 to 50 V and a maximum output current of 9.5 A. Pololu 4090

This small synchronous switching step-down (or buck) regulator takes an input voltage from 4 V to 36 V and efficiently reduces it to 3.3 V. The board measures only 0.7″ × 0.7″ yet delivers a typical continuous output current of up to 2.6 A and features reverse voltage protection.

The Step-Up Buck Voltage Regulator module with adjustable output voltage in range of 2.5-9.5V with a input voltage range of 1.5-16V and a maximum output current of 2A. Pololu 791

The S9V11F5 switching step-up/step-down regulator efficiently produces 5V from input voltages between 2V and 16V. Pololu 2836

Przetwornica DC-DC Step Down (MP1584), Uwe 4.5..28V, Uwy regulowane 0.8..20V, RoHS

Step DC-DC converter, Uwe 3.5-30 V, adjustable 4-30 V, RoHS

This small synchronous switching step-down (or buck) regulator takes an input voltage of up to 38 V and efficiently reduces it to 9 V. The board measures only 0.7″ × 0.7″, but it allows a typical continuous output current of up to 2.5 A. Typical efficiencies of 85% to 95% make this regulator well suited for powering moderate loads like sensors or small motors.

The Step-Up / Step-Down S18V20F12 inverter module gives the output voltage of 12V with a wide input voltage range of 3 ... 30V and a maximum output current of 2A. Polol 2577

Pololu 5V Step-Up/Step-Down Voltage Regulator S18V20F5

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.

Pololu 2832

This small synchronous switching step-down (or buck) regulator takes an input voltage of up to 38 V and efficiently reduces it to 6 V. The board measures only 0.7″ × 0.7″, but it allows a typical continuous output current of up to 2.5 A. Typical efficiencies of 85% to 95% make this regulator well suited for powering moderate loads like sensors or small motors.