YwRobot Breadboard Power Supply

Breadboard Power Supply Module

The MB102 is a breadboard power supply module manufactured by the YwRobot Corporation in China. This module has the marking 545043 and MB V2 on the printed circuit board (PCB). It provides dual 5 V and 3.3 V power rails, and has a USB socket. This multi-page article might prove useful to anyone considering buying it, or needs to know how it works. The manual I received came with a small sheet of paper stating only the input voltage and current levels, however this MB102 manual may provide more information.

I performed a short circuit test by shorting the power supply rails for a full minute, and surprisingly the voltage regulators continued operating properly. I noticed that the 5 V regulator heated up, but when the short was taken away it cooled down and continued to operate within normal parameters. I then repeated the test to measure the loading on the power source when the voltage regulator output was shorted, and I am glad to say that the source remained protected. This is really due to the built-in protection that the voltage regulators have.

Since the green power LED is connected to the output rail, when I applied a short to either of the voltage rails it would go out, hence this is an excellent indicator of a short in the power rails that the hobbyist can make use of when building breadboard circuits.

YwRobot appears to be a Chinese firm that sells a lot of these to their domestic educational establishments; however, some of their products can end up on eBay, and Amazon, selling to worldwide markets. Nevertheless, it is amazing that they can sell this for less than £2.00 including postage!

Barrel Socket Power Input

USB and Barrel Socket Power Input

There is a green LED to indicate the presence of power, and an ON / OFF latching switch to control the power to the board. On this particular model and version, the centre pin of the barrel socket is positive; however, please double check with the manufacturer’s instructions, in case they have made any changes. You have to push the switch IN to use this device. The operating instructions state that the input voltage through the barrel socket must be between 6.5 V and 12 V. Hence, if you wish to use it to its maximum capability, then you will need to remain in that range. This is a non-adjustable fixed power supply model, which is good enough for most applications. The manual states maximum output current to be 700 mA.

Jumper Pins and Headers

Jumper Pins and Headers

In this design, the jumper pins are used for selecting the voltage levels on each side of the breadboard power rails. You can choose between 5 V, OFF, and 3.3 V. There are two sets of jumper selectors for each side of the breadboard power rails; hence, you can have any combination of voltages on either rail. In addition, there are also header pins for tapping off voltages, using a cable or jumper wires.

Voltage Regulator AMS1117 Spec

Voltage Regulator AMS1117 Spec

The AMS1117 is a voltage regulator manufactured by Advanced Monolithic Systems. There are two regulators where one regulator establishes a 3.3 V rail, whilst another establishes the 5 V rail. These are a good set of components found in a SOT-223 package. Their documentation states that this series can provide a maximum output current of 1 A, and the absolute maximum input voltage rating is 15 V. The documentation also indicates that these regulators have built-in protection against short-circuit through power limiting circuitry. There is also thermal overload protection circuitry, which will shut-down the regulator should its junction temperature reach 165 °C.

These regulators also have internal diode protection and can handle transient surge currents from 50 A to 100 A. This is a high efficiency low dropout regulator, which can operate down to 1 V, hence it has a 1 V input-to-output differential making it useful for battery powered applications. The line regulation is 1.2 % and maximum load regulation 0.4 %.

The AMS1117 series is an excellent choice for creating adjustable power supplies as well. The package provides a 1.25 V reference voltage from the adjust pin, and with a pair of resistors in a voltage divider network the regulated output can be adjusted. The documentation is also very clear and comprehensive in its use.

How to use a Breadboard Power Supply

How to use a Breadboard Power Supply

This is a plug-in power supply, and the headers below the board simply plug in to the breadboard. Once installed, the voltage rails to both sides on the breadboard then provide power. You then use the yellow jumpers to select the voltage levels required. This is a dual output (3.3 V, and 5 V) regulated board and you can have either voltage on either rail on the breadboard, which is very useful.


I thought the PCB manufacturing was of good standard, and the markings indicate the model MB V2, known as MB102. This is obviously a double-sided board that is machine assembled. There are two sets of mounting header pins, and the ones on the front are if you want to use the holes on the outermost edge of the breadboard thereby using the least number of tie points.

Static Bag

Static Bag

The board arrives packed in an antistatic bag like this, so the manufacturer obviously cares and has made an effort to ensure that the product is protected in transit. This one came with a single sheet of paper with the following written on it.

MB102 Breadboard Specification

  • Locking ON / OFF Switch
  • LED Power Indicator
  • Input Voltage: 6.5 V to 12 V (DC)
  • Output Voltage: 3.3 V / 5 V
  • Maximum Output Current: 700 mA
  • Power Rails 0 V, 3.3 V, 5 V on Breadboard
  • Two Groups of Header Pins
  • Size: 5.3 cm × 3.5 cm

The manufacturer may make revision changes to their product, changing their voltage regulators and components, therefore, you should always follow the instructions that came with your product. When you receive your board, it is a good idea to check the output voltage levels with a digital meter to make sure that it is operating correctly and providing the correct voltage levels. You should get exactly 3.3 V and 5 V at the outputs. You should also thoroughly check your breadboard project circuit, and double check all the voltages before you connect it to anything else.

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