In-line Laptop Surge Protector With an Outlet




Introduction: In-line Laptop Surge Protector With an Outlet

About: I'm a graduate of Aircraft Engineering Technology (Hons) in Mechanical. I am passionate about energy, electric vehicles, gadgets, tools. My projects basically reflects my needs.

In the fall of 2007 my HP TX1000 stopped working and won't turn on, upon sending it to repair shop (I believe it cost me about AUD$80 just to check what the fault is....grrr) they said that the mother board has to be replaced and it will cost about AUD$800. I asked the technician what caused the laptop to become faulty and he mentioned that the power surge caused the motherboard to become a junk.

Upon thinking, I thought instead of repairing it for AUD$800, I could top up little more money and get a new one. Since I wasn't using the touch feature or tablet mode on that laptop ever and also felt it was bulky. So went to Harvey Norman's website and checked out for my new laptop and found this Sony VAIO VGN-CS16G in various colors and I wanted white, loved the island keyboard, the overall design and the price. Went to store next day and bought it along with you might have guessed it ... a SURGE PROTECTOR...

I was using it all the time whenever I connect my laptop to mains power. After moving out of Australia. I had difficulty using the surge protector due to different plug types in other countries I've been to. I remembered that when I was purchasing the above surge protector the store person showed me another option which is in-line type and can be connected in-line with the laptop charger itself. But it was pricey compared to the above one. Obviously I did not think about the plug type earlier and looked at the price tag... So out of necessity and to avoid carrying multiple traveler adapters I opted to make one so that I can save money as well as protect my laptop...

I had this for more than 3 years and it has served me well.. at least my Sony isn't busted...

Enough of history, now onto the built...

Step 1: Designing the Surge Protection Circuit

I was a fresh newbie to electronics so I didn't had any clue on what a surge protector circuit will be like. Therefore I decided to open up the surge protector I had and check its circuit and hopefully find what has to be done.

I have to give credit to the 'ible wirter throbscottle with his 'ible I was able to reverse engineer the circuit. Though this is fairly a simple circuit to make I followed the way (roughly) the above author mentioned (remember I was a fresh newbie).

You can go through his instructable for the steps to reverse engineering circuits using pictures of the actual circuit board, the best part is all of it can be done using freewares.

The pdf version of the circuit used for this project has been attached, as well as the eagle .brd file is attached.

The circuit's specifications are 240VAC, 50 Hz, 10Amp Max, 2,400W.

Step 2: Components and Tools Required

Parts/ Components:

  1. Single sided PCB
  2. 3 x CNR 20 D 431K (Metal Oxide Varistor - an electronic component with an electrical resistivity that varies with the applied voltage - Source: Wikipedia, the link will take you to Wikipedia page.)
  3. LED 5mm or 3mm (your choice of color)
  4. 1N4001
  5. 33K resistor
  6. Enclosure
  7. Three pin connector that is compatible with laptop charger's AC input socket (can use old laptop charger for case and the AC wire with the plug used to connect the charger)
  8. A socket (refer pic) (optional)
  9. AC switch (optional)

Tools & Consumables:

  1. Drilling Machine with drill bits of various size
  2. Utility knife
  3. Soldering iron
  4. Solder
  5. Hot glue gun and 1 or 2 glue sticks
  6. Small files (optional)
  7. Your choice of method for producing PCB. I have used toner transfer method and it worked fine.

You will be working with high AC voltages, so please be careful and take necessary precautions to avoid getting shock. This is lethal and must be handled properly. I am not responsible if you damage any of your equipment following this. It worked for me and you should be aware of what you are doing.

Step 3: Making the Circuit

There are rather large number of instructables and tutorials available on the process of making PCB therefore it is not gonna be described here. However I will provide the links for various methods that I came across, feel free to use any method you prefer.

The PCB is larger in length, I chose it so that it won't rattle around and will more or less press fit inside the enclosure. The position of the LED was placed so that it aligns directly under the plastic on the upper side of the case that shows the device in ON state.

Methods to make PCB:

  1. Toner Transfer
  2. Photo Resist 1, 2, 3
  3. Laser etching spray paint
  4. Printing directly onto PCB

Use what best suits for you.

I have also gave it a shot to make colored PCB (by icecreamterror) and it didn't worked out very well but I am happy with it.
To make a colored PCB, take a permanent marker such as sharpie (your choice of color) and draw all over the clean PCB.

Take a kitchen towel or some cloth and dab paint thinner/ acetone and rub onto the PCB to make the streaks made by the marker disappear and to make the color look even. Thats it...

Step 4: Populating the PCB

As per the circuit populate the PCB, the pictures are self explanatory. Bend the leads of the components to accommodate the space inside the enclosure. After populating the necessary components, place it inside the enclosure and check it to ensure it is working.

Strip of the wire with the plug and solder the wire onto appropriate places on the PCB.

The old charger's enclosure was used in this project.

I do not have any pics of gutting the charger. However it is fairly simple to do.

Use a knife to run along the connected part of the charger and you should be able to open it.

Take out the circuit and use components from them if you want.

Keep the enclosure and the socket we will be using it in our project.

Step 5: Making the Enclosure and Extra Socket

The original in-line product did not have any extra socket to use additional device and that was one of the drawback that made me choose the other.

Therefore an extra socket means that I can use it to connect printer or other devices easily and when in public place like library you cannot find a free socket to plug in your laptop, just ask a person to connect to your extra socket and both can benefit!!!

Hey not everyone's laptop battery can withstand for long time... my battery is dead within half-an-hour if disconnected from mains.

Now onto the Build...
Took the socket I want to mimic, placed a paper over it and hold the pencil at an angle and go crisscross to make the pattern.
Use a knife to cutout the unwanted portion. Now your template is made.

Place the enclosure so that it doesn't move around and then place the template on suitable area.
Now using a drill make holes and use knife and or files to make the socket opening.
The socket used was salvaged from an extension board thrown away by someone.

Took a traveler adapter and checked for the fitting by connecting the adapter to the socket through the hole.
Do the same procedure to make the hole for the switch.

Make necessary connection and hot glue the socket in place.
Ensure to cover the exposed connections using hot glue.

Place the top and bottom of the enclosure and hot glue it together. For a clean look you can use a hot knife to run around the joint to remove excess hot glue and to make it appear smoother.

Upgrades: Thought of incorporating a 5V 1A USB charger into this but the space was a constrain therefore left that one out.

Step 6: Connection & Usage


It is very easy to use and does not require any travel adapters. I am fairly confused on how to explain it... lol

The DC output from the charger is connected to your laptop.

The charger is connected to the output of the surge protector. The input of the surge protector is connected to the mains using the wire that came with your laptop.

That's how I protected my laptop from becoming a victim to voltage surges.

This circuit can also be made to protect your other electronic devices from voltage surges.
And has following specifications 240VAC, 50 Hz, 10Amp Max, 2,400W.

If you do make it post your pics in the comment section.

Any suggestions and comments are welcome.
And kindly vote for it, if you like it.

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MAKE ENERGY: A US-Mexico Innovation Challenge

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    8 Discussions


    5 years ago on Introduction

    I've always been worried about how to protect my laptop. This is a great and convienient way to protect that portable device. Great job at explaining each step!


    Reply 5 years ago on Introduction

    Well, now I know how to do it myself, it was 2007 and I was a newbie when it comes to electronics and the shop guy said it is $800... the laptop was almost one year old at that time.


    5 years ago

    Think you could have just reused the entire pcb.