Introduction: Convenient Jumper Wire Power Supply

This is a small adjustable (0 to 16.5V) power supply module modified to make connections to solderless breadboards and various modules easier. The module has an LCD voltage and current (to 2A) display, but this project adapts the module with a few simple parts to make it easier to use jumper wires to power projects.

I'd like to credit my dad for a rule: "If you are going to do things the same three times, make a tool." I'm sure he taught me that, but over my lifetime I've watched him NOT use that rule. Usually, projects would turn out better if he had followed that rule. As a Dad myself, well, I need my son to remind me, too.

The basic rule is that if you find yourself doing the same thing for the third time, consider making it easier by making a template, jig, or tool. If you have a tool that helps you reduce some effort, the time spent making the tool will save you on the 3rd, 4th, and perhaps 100th time that you have to do something without the tool.

I was thinking of this the 3rd.. er... 20th time that I connected a bench power supply to a solderless breadboard to power up some electrical experiment. Somewhere in my collection of various electronic modules, I knew I had a variable voltage DC to DC converter that had a small LCD display for voltage and current, as well as some VERY small breadboards (5 rows of 5 connections each) and decided to use these to make this Jumper Wire Power Supply. Make it once, use it often.

Step 1: Parts List

The first step is obtaining all of the parts. I found the DC to DC module that I knew I had buried somewhere. All the other parts came out of my parts bin. Using the exact parts that I used in this Instructable isn't necessary. It is easy enough to customize for the parts that you have available or the specific features that you want.

The DC to DC module is available on eBay, Amazon, or other on-line electronics vendors. Above are pictures of the module bare, in the case, and of the case itself. The module I had came with this simple to assemble clear case.

If you buy it on eBay, buy from a vendor that you trust. At the time of this writing, the module was available for under $8 USD from here:

Pictured above is a green 70mm by 90mm PCB that I used as the base for this project. Also in that picture are two of the three 5x5 micro-sized solderless breadboards, some pin headers, an LED, and a power jack.

There are a couple parts missing from that picture, but I didn't have the presence of mind to take a picture of the parts all gathered together as I assembled this project. So you should add to the list another LED, a couple of resistors, a switch, and a few more of the straight and 90 degree headers.

Since you don't need to duplicate what I have done with this project exactly, feel free to change this to suit your needs. As built, it is easy to plug in this module, dial up a voltage, and use jumper wires to bring power to your circuits. Other jacks/connectors could supplement what you see here.

Step 2: Power Supply Module Specifications

This isn't an assembly step, but it is a list of the module's technical specifications from one of the sellers.

DC-DC Adjustable Step-down Converter Features:

Clear and large LCD display, blue background and white digit, reading voltage and current at the same time.

Input voltage range is DC 5-23V, suggested voltage range is lower than 20V

Continuously adjustable output voltage 0-16.5V, the input voltage should be at least 1V higher than the output voltage. Automatically saves the last set voltage.

Unique design: two buttons for adjusting the voltage, one for reducing the voltage, the other for increasing the voltage,

This step-down voltage power module uses imported MP2304 chip; 95% conversion efficiency, +/- 1% accuracy, low heat generated.

Output current: 3A Peak, recommend the use of within 2A. (Over 2A, please enhance heat dissipation.)

Accuracy: 1% High conversion efficiency: up to 95%

Load regulation: S (I) ≤0.8%

Voltage regulation: S (u) ≤0.8%

Module size: 62 x 44 x 18mm

Step 3: Screw Terminal Removal

The DC to DC module can be used on its own, by running wires to the screw terminals, providing power on the left screw terminals and getting regulated voltage from the right screw terminals. But NOT having to use screw terminals is the point of this project.

This step is the removal of the two screw terminals so that wires can be run from the PCB connections to the green "sea of holes" PCB.

I used a solder extraction tool that employs a vacuum and heated nozzle to suck away the melted solder. Another method to remove solder is to use solder braid.

The two screw terminals are removed and saved. They will be reused.

Step 4: Soldering DC to DC Module in Place

The DC to DC module is test-fit onto the upper half of the board atop the back piece of the case. Note that the case is clear acrylic, but that the pieces have brown protective paper on them. This paper needs to be peeled off before the case is assembled.

The case parts also come with two red acrylic pieces that are used to extend the height of the voltage up/down buttons of the module. Take note of these red bits. You will laugh at me later.

Also worthy of note is the silkscreen on the back of the module. No, not the "Winners" logo. Note the input, ground, and output connection order. For reference: From the top of the module reading left to right is INPUT, GROUND on the left side, and OUTPUT, GROUND on the right side.

I used four wires soldered to these input and output connections. The leads were scrap wire clipped from the long leads of LEDs for some other project. These wires connect the module to the green PCB.

With the back case part and the DC to DC module in place, these leads were soldered to the green PCB.

Step 5: The Clear Case

The first photo above shows the little acrylic parts fo the long edges of the case. When the case is assembled normally, the two larger "knobs" on those parts stick through the back case piece and act as little feet for the case. Since this case is being mounted flat on the green PCB, these feet need to be removed. Note in the photo that I used a knife to scribe along the part where it needed to be shortened. I scribed with the knife a few times on each side and then used a pliers to snap off the "foot" of the piece.

I assembled the four side case parts to the back of the case after removing the brown protective paper. These parts were all glued together with good old E6000. Love that stuff. The front case piece with the brown paper on it wasn't glued but put in place to make sure that the other parts lined up correctly. I let this dry/cure for about an hour.

The brown paper was removed from the front cover. This part would normally be held in place by the two machine screws that came with the case. The screw holes on the front of the case are sized so that the screw easily fits. The matching screw holes on the back part of the case are slightly undersized so that the machine screw taps its own threads in that acrylic. This works well when the case is assembled with the "feet" not cut off, as that screw sticks out the back a little bit. With the case mounted flat to the PCB, the screw is too long.

So I made the hasty decision to forego these screws and just glue the front case piece on. I again used E6000 and allowed it to cure.

Remember the red acrylic button parts? Well, I didn't. I glued that front part in place without remembering to first put in the red bits. So to fix this I trimmed the red bits to be a snug fit and inserted them from above. The careful trimming keeps those parts in place.

Step 6: Placing Parts on the Board

The screw terminals were reused by placing them on the green PCB for both input and output. This is optional, of course, as you can choose other ways of bringing power to the board. I did mark the terminals with a black Sharpie for ground and with a red Sharpie for positive voltage.

Three 1x5 headers were mounted on the board. These headers can be used with the female single wire jumpers commonly referred to as "Dupont" jumpers.

The three 5x5 micro-sized solderless breadboard bits have some sort of plastic protrusion on the bottom that needs to be removed. I used a box knife to remove the little hollow cylinders.

The 4th picture illustrates a 90 degree bent 1x5 header placed in the blocks. This is how the connection is made to that block. Another single 90 degree pin (pic 5) stripped of its mounting plastic in conjunction with a single straight pin is what it takes to make the connection from the block to the green PCB.

Again I used good old E6000 cement to glue the solderless breadboard block in place.

Step 7: Connections and Rubber Feet

All grounds are connected together, including the black block and associated pins.

The voltage input connection of the screw terminal and the barrel jack (center positive) are wired in common. The pushbutton switch (push on, push off) makes the connection of the input voltage to the DC to DC converter, and the yellow block and associated pins. There is a yellow LED/resistor (330 ohm) also on this node.

The red block, pins, LED, and screw terminal are all connected to the DC to DC converter output voltage.

Everything was laid out carefully so that bare wire running on the back of the PCB made all but one connection. An insulated wire was used for that.

Four rubber feet (bumps) were placed on the back corner of the board to keep the live connections off of the surface that this board sets upon.

Step 8: Beauty Shots

Here are a couple of pictures of the top of the project, as well as the input and output sides of the assembly.

Step 9: Calibration

The module that I had displayed 5.01V and my meters agreed that the actual output was 5.09V. This error can be fixed.

To calibrate, hold down the left (voltage decrease) red button while powering up the unit. The display flashing means that it is in calibration mode.

Press voltage down and/or voltage up (the right side red button) to have the display of this DC to DC converter match the display of a voltage meter connected to the output.

Cycle power.

Step 10: Use

The first picture above shows two LED modules from connected via female to female (commonly called "Dupont" connectors, although this isn't always the case) to the black ground block and red output block.

The second picture shows a Sensor.Engine:MICRO (SEM)being powered by this project. Certainly, other boards, such as the ubiquitous Arduino, can also be used. The 32-bit SEM can be plugged along the edge of a solderless breadboard.

The video uses the PWM output of the SEM to drive an IRF520 MOSFET module (see the docs here) that uses the 12V input connection (yellow block) to control a small 12V bulb. The code makes the bulb transition on and off like breathing.

This is the code that runs on the SEM:


a = 1

b = 1

c = 1

PWM 1, 1000, a, b, c


for a = 0 to 99 STEP 2

PWM 1, 1000, a, b, c




for a = 100 to 1 STEP -2

PWM 1, 1000, a, b, c





You can see it is pretty simple to code something on the Sensor.Engine:MICRO to use this Jumper Wire Power Supply.