Introduction: How to Make a Molex Power Supply

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This is to show you how you can easily make a molex power supply for your hard drives/ optical drives etc. with a simply 12V DC adapter. You will need a few things to get started:

-Soldering Iron
-Two pieces of Wire
-Voltage Regulator
-Screwdriver (If you have an adjustable voltage regulator
-Block Terminal Connector
-12 Volt DC Power Adapter (I have one here which does 1.5 Amps, from an old wireless router)

Step 1: Decide Which Wire Is Which

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Just to be 100% certain, using your multimeter, find out which of the lines coming off of the adapter is positive and which is negative. Then once you are sure, put some tape on it or something so that you can be remember which wire is which. 

Then you can start stripping your wires, strip the 4 wires form the molex plug, and then strip 2 pieces of wires on both sides so that you can use it to connect the power supply to the voltage regulator. 

Step 2: Tinning the Wires

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Then you can start to tin the wires on the stripped sides. This is done so that the strands dont go everywhere and are together, also to make sure that the strands are connected to each other. 

Step 3: Soldering Wires Onto the Regulator

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You can the begin to solder the small pieces of wire to the voltage regulator. Make sure that the wires are being soldered onto the input side of the regulator. Also make sure that there is a good connection from the wire onto the regulator.

Once the input wires have been soldered onto the regulator, you can then solder on the molex plug on the output side. Be sure to connect the RED and one of the black wires to the voltage regulator. Using the same procedure, solder the RED wire onto the +Output of the voltage regulator and a black wire onto the -Output of the regulator.

Step 4: Connecting Everything Up

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Once the molex plug has been connected to the voltage regulator, you can then connect up the YELLOW and the other black wire.


I have simply twisted the wires together as the will be going into a block terminal connector, there was no need to solder.

So the YELLOW wire goes straight to the molex plug, and so does 1 BLACK wire, then the signal goes to the voltage regulator, where it is regulated to 5 V DC, and then the RED wire comes off of that and so does the other BLACK

Step 5: Setting the Voltage Regulator

Picture of Setting the Voltage Regulator

This step is not necessary for everyone as not all of you will have a variable voltage regulator, but what you simply do is turn the screwdriver one way until you see the voltage drop to what you need to. I had set my regulator to give out 4.90 Volts because power supplies usually give out about that much. I could make it go up to the 5 Volts but I decided to leave it a tenth of a volt lower as the full output of the "12Volt adapter" was only really around 11.7 Volts. 

Step 6: Enjoy!

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You can now use your molex adapter to power things that you need like Optical Drives, Hard Drives, or in my case, my HDD Grinder!

Be sure to insulate the voltage regulator and wires, or make sure that they don't come into contact with each other causing a short. 


miraheng (author)2016-07-23

what if i want 12v supply for leds

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