Monday, February 22, 2016

Make Mini UPS For DSL Modem PART-VI

This is the sixth and last post in a series of posts on making your own mini UPS for DSL modem. Be sure to read the first five parts before you read below.

In the last five parts we discussed various things that should be considered when making a UPS. I wrote an overview of the mini UPS in first part, about the load (a DSL modem) in second part, about batteries in the third part, about recommended charging algorithm in the fourth part, and the circuit diagram of the mini UPS in the fifth part.

Throughout all these parts, whatever I wrote was for beginners. In this part I'll try to show you how you can too make this mini UPS yourself.

Before you read further take a look at the pictures of the mini UPS that I built for myself.

Mini UPS with Battery Top View
Mini UPS with Battery Top View

Mini UPS with Battery Front View
Mini UPS with Battery Front View

Mini UPS Top Cover Removed Inside View
Mini UPS Top Cover Removed Inside View

The two brown boards, the small one on the left and a big one in the center, are printed circuit boards. The third thing on the right is the transformer. Above the transformer there is a IEC 60320 C14 male connector and there is also a fuse holder. Toward the left there are two leds, green and red. The green indicates the presence of AC power and the red indicates that the battery is charging.

The Printed Circuit Board


A printed circuit board (PCB) is a board with electronic components mounted on it. The components are connected electrically using conductive copper tracks. The components may be through hole or surface mount.

The easiest and most widely used method to make PCBs at home is toner-transfer method. Before you make a PCB, you should buy components. When you have bought the components, design the board in a CAD program. The design of board involves placement of the components, routing the copper tracks to create electrical connections between the components. The outcome of this activity is commonly called board layout. Many programs are available to accomplish this task. Some are OrCAD, Proteus, EAGLE.

I designed the PCB of my mini UPS in CadSoft EAGLE software. There is a light version of EAGLE which is completely free of cost. There are some limitations in the light version. One is the board dimensions are limited to 100 mm by 80mm. Due to this limitation I had to design two boards. One for the battery charger and the other for UVLO.

After you have the board layout you can either send the layout files to a PCB fabrication house or make a PCB using minimum supplies at home.

Making A PCB At Home


Watch this video carefully to understand the process of fabricating a PCB.


Video by JumperOneTV/Youtube

As seen in the video, you need these things.

  1. Glossy Paper (at least 150 g/m2)
  2. Laser Printer
  3. Copper Clad Board
  4. Scotch Brite Sponge
  5. Electric Iron
  6. Ferric Chloride
  7. Acetone
  8. Drilling Machine

Download Eagle files
Download PDF files ready for printing on glossy paper

Download the PDF files, print on glossy paper and then follow the procedure shown in the video.

Final Thoughts


Making the PCB of this mini UPS could be difficult for you if you have never made a PCB before. If you are interested in making the PCB of this mini UPS, first get the components. After you have got all the parts, try to etch the PCB. You might fail. You might get broken traces. You might wait for hours but the etching process would not start at all. Don't worry, it happens with all. Try again! Ultimately you would have a good looking PCB. Then you would have to solder the components to the board. Soldering is very easy, more easier than etching the PCB. After you have soldered all the components, connect the power supply and test the PCB to determine if it actually works. If it works, congratulations! you have build your own UPS.

I hope you have enjoyed reading all the articles as much I enjoyed writing them. Electronics is so much fun. If you have not understood anything feel free to ask in the comments below. There is no such thing as a stupid question. Not asking questions is stupidity!

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