How to Use a Breadboard Power Supply Module

This is an in-depth guide on how to use a Breadboard Power Supply Module to provide 3.3 Volts or 5 Volts DC for your breadboard projects.

Why do we need a power supply module for a breadboard? Because the module simplifies the process of powering your prototypes, saves time, and reduces clutter in your breadboard. Most microcontrollers and development boards operate at 3.3 Volts or 5 Volts DC power supply. For example, Arduino UNO operates at 5 Volts whereas ESP32 is a 3.3 Volts compatible board. A DC breadboard power supply module eliminates the need for additional circuits to power your projects, making prototyping faster and simpler.

Table of Contents

Introduction to the Breadboard Power Supply Module

The MB102 Breadboard Power Supply Module does not support all sizes of breadboard. These modules support the MB102 breadboard which has a width of 5.5 cm (2.165 inches). The MB102 breadboard comes with a standard 830 points for connection and has a pitch of 2.54 mm (0.1 inch).

The MB102 Breadboard

Electrical Specifications of Breadboard Power Supply Module:

Input Voltage	DC 6.5 Volts to 15 Volts
Output Voltage	3.3 Volts or 5 Volts
Maximum output current	1 Ampere

Breadboard Power Supply Module Pinout

The breadboard power supply module features a DC barrel jack connector for input power. A push button switch is used to turn ON the module and an LED beside the switch shows the power ON/OFF status.

If we supply power through the barrel jack, we will obtain 5 Volts output at the USB port. External peripherals can be powered via this USB port.

Four sets of pins provide an output voltage to the MB102 breadboard’s power rail. In each set of pins, one pin in output is ground and the other pin’s voltage can be configured to either 3.3 Volts or 5 Volts with respect to ground.

The module also has header pins for voltage output to Dupont/jumper wires.

Circuit Diagram

The following schematic describes how the components onboard the breadboard power supply module are wired:

Components description:

D1: 1N4007 Diode used to prevent the flow of current back to the input source
C1, C2, C3, C4: Bypass capacitors
U1 and U2: Low Dropout Voltage regulator ICs
D2: LED to indicate power status
R1: Resistor to limit current to the LED

Powering the Module

The breadboard power supply module is powered using a DC barrel jack. AC-to-DC power converters or a 9-Volt battery can be used for the DC supply. The DC barrel jack should be center positive (dimensions: 5.5mm outer diameter x 2.1mm inner diameter).

Commonly found power supply adapters with 9-Volts or 12-Volts output are suitable for the module. The current output of the power supply will depend on the power requirements of the circuit on a breadboard (500 mA to 2 A should be sufficient in most cases).

The USB port can also be used as an input instead of the barrel jack i.e. the USB port can act as both input and output. Powering via this port will be convenient if you have a USB cable with Type-A connectors on both sides of the cable. This method is not discussed further in this article.

Two Low-Dropout Regulators (LDO) ICs, both A1117, step down the voltage in the breadboard power supply module. These three-terminal devices have adjustable or fixed output voltages. The A1117-5.0 IC is configured to give a 5 Volts output, while the A1117-3.3 IC provides a 3.3 Volts output.

The recommended maximum input voltage of A1117 is 15 Volts. The IC drops a voltage of 1.15 Volts while regulating a load with 1 Ampere of current consumption.

When the breadboard power supply module is turned ON by pressing the push switch on the module, the following occurs:

Voltage from the DC barrel jack gets fed to the input pin of the A1117-5.0 LDO IC
The A1117-5.0 IC gives an output of 5 Volts to:
- the USB port
- pin headers JP1 & JP2 (refer schematic)
- the input pin of the A1117-3.3 IC
The A1117-3.3 IC gives an output of 3.3 Volts to the pin headers JP1 & JP2 (refer schematic)
Depending on the position of the jumpers in the pin headers JP1 & JP2 (output voltage selection jumpers) we get either 5 Volts or 3.3 Volts as output in each set of output terminals

How to use the Breadboard Power Supply Module

The breadboard power supply module easily plugs into the power rails of both sides of an MB102 breadboard.

The power rails are arranged in both the edges of the breadboard. A typical breadboard has two power rails on each side, one for the positive voltage and one for the ground. The image below shows the front and back sides of a breadboard with the power rails marked by red arrows. All the holes in the same power rail are shorted internally via metal strips in the breadboard.

If we supply voltage to one of the holes in a power rail, all the holes in a power rail will be raised to the same voltage. Note that in a full-sized breadboard, there is a gap between each set of power rails (the circled areas in the diagram). We can use small jumpers to bridge this gap and extend the power to the other rails (as shown below).

The jumpers in the voltage selection pin headers can be moved to select the voltage output to a power rail. If we set the jumper in the 5 Volts position, we shall get 5 Volts on the output pins beside the jumper. In the OFF position, there is no output voltage.

Similarly, if the jumper is set to the 3.3 Volts position, we can power the breadboard rails with 3.3 Volts with respect to ground.

Look for the plus and minus signs on the breadboard power supply module to identify positive and negative rails on the breadboard.

Any ground rail can be used while connecting the components.

⚠ Verify the wiring is OK before turning ON the breadboard power supply module. Incorrect connections may cause a short circuit. The breadboard power supply module does not have fuses to protect against high currents.

Example: Powering an LED

This example will help you use the breadboard power supply to power an LED. Keep the power supply switch in the OFF position before connecting the components.

An LED requires a series resistor to limit the current flowing through it. Connect a jumper wire from the 5 Volts rail to the anode(+ve) of the LED through a 220 Ohm resistor. The cathode of the LED should be connected to one of the ground rails of the breadboard. Here is the circuit assembled on a breadboard:

When you turn ON the breadboard power supply module, the LED must light up. Congratulations if this was your first attempt at testing the module.

Final Thoughts

This guide explained what a Breadboard Power Supply Module is, how it works, and how we can use it to power electronics projects. The module is ideal for beginners and hobbyists who want to avoid more complex power setups. But it also has its limitations such as support for high output currents or the flexibility to get a variable output voltage.

If you would like to make a variable DC power supply for your breadboard projects, read our comprehensive article – Make a DC Variable Voltage Regulator using LM317.