Introduction: $3 MINI PROJECTOR

About: I Make Simple.

Hello! This time i am here with a small mini projector just out of $3 . This is a very fun project to make and pretty easy to make.You need to switch off the lights and watch the action! It is powered by a mobile phone or any digital media player.It's quality is very good if you will use a good phone with full brightness and high contrast. The better the brightness and contrast  is the  better is the projection. The mobile i've used here has very less features and my dad won't allow me to do this with his expensive phone so i have to use a bad one with bad quality , very less brightness and contrast but i assure you if will use a good bright  mobile phone with good brightness control you will get very good quality! I can't show you it's working image because i don't have a mobile with a bright screen and my camera is not catching that much low light but i assure you it's visible! I f you are not getting that quality tell me what problem you are having!

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Step 1: Technical Details.

This projector works on the principle of magnification. The brighter the image from the source is the better is the quality of projection.The source should be held upside down or the projector box  should be upside down to get a correct image on the canvas.The room should be kept dark. The distance between the source(the mobile phone) and the lens should be adjusted  (Keeping the distance between lens and the canvas constant means)accordingly to get a non blurry image on the canvas. The words or the alphabets will be right side left.

Step 2: Grab Stuff!

Once you had decided to make one of your own you need to grab some general stuff!

1. Get The lens (You have to open a old film camera out of scrap!)
  • Take the camera.
  • Open the casing.
  • Remove the lens by screwing out the screw.
  • Now you have the lens.
2. A card board

3. Hot glue gun.

4. A pair of Scissors

5. Blade

6. Opaque  Tape.

7.  Pencil and other stationary.

8.  A big white canvas.

9. A good mobile phone.
  • Having Adjustable brightness.
  • 200 ppi Screen (You can still use a bad quality but it will be better to use a good one.)
  • Having Adjustable Contrast & Color.

Step 3: Making!

Now here is the step by step description of the build!

1. Take a piece of cardboard and mark two rectangles on the cardboard with pencil according to you mobile phone's dimension

2. Now cut them out with scissors.

3. Now cut one10cm wide and xcm (xcm refers to the width of your mobile phone) long rectangle from the cardboard it will be used as the base of the projector.

4. Now make a whole box using hot glue or other adhesive by making the out two side but you have to  leave  one side which faces the front side of the your mobile phone.

5. Take the side which is left and mark a circle according to the lens radius at a place which face the middle of the screen of your phone (i have marked it little bit on the left side because my screen's center if at the left side.)

6. Cut the hole with blade and fit the lens there and stick that side with the box now.

7. Tape the edges so that any light comes out.

Now check the quality you are ready now just the lid and the adjustment is needed.

8. Now you can see in the image marked as (show1) that the quality is not good sobring the mobile close to the lens and put the projector away it will improve the quality.

9. Now paint the projector and do whatever you wanna do!

NOTE: Put you phone at the brightest mode and highest contrast before using it with projector.

Step 4: Author Tips.

1. The room should be dark  where you are going to use the projector.

2. The lens should be clean.

3. It's ideal for watching movies.

4. The brightness should be at maximum level.

5. The colors should be set to vivid.

6. The contrast must be high.

7. Slow after some tests you will learn how to make adjustments of the distances.

Thank you for going through my project! If you have any doubts you can make a message.

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    10 Discussions


    5 years ago on Introduction

    Hi, I tried this buy all I am getting is white light out of the box :-(. please can you help?


    Reply 5 years ago on Introduction

    Get me on facebook , my name is samadmamanhaque. (Until instructables launches a chat service :( )


    Reply 5 years ago on Introduction

    Sorry I am not on facebook. Please can you hint what could be the reason. Is the box too big, the phone not bright enough, or the lens is not powerful enough.


    5 years ago on Step 4

    I bought a cheap Google Cardboard kit and noticed this same thing happened, and thought, "what if I used a higher quality glass lens", and I see that that's exactly what you did.

    It took me hours of time, a box shipped around the world, and a $600 phone to not come close to what you've done with $3. That's really impressive.

    I'll be going to the thrift shop in the next few days to get some lenses (I have a bigger phone, so I'll probably need a bigger lens(?)), and I'll let you know how it goes!

    I also had the idea to somehow pump more light into it, but I have no idea how I'd even do that. I'll work on it.

    Thanks for the great guide, and the wonderful inspiration!


    Reply 5 years ago on Step 4

    Sorry bud but i am the author i just forgot the password of my account so i made a new one!

    Now yes if you have a $600 phone the make it to the highest brightness , take a wider lens and the magnification also depends on the ppi (pixel per inch or simply how high picture quality your screen can deliver! if you have other problem you may contact me on facebook or by mailing: samadhaque23@gmail.com or samadmaman haque on facebook!


    Reply 6 years ago on Introduction

    It depends on what screen size you want ! But the max i have tried with my old phone it is around 25cm*20cm. If you will use a phone having high brightness and contrast !


    Reply 6 years ago on Introduction

    I have a problem with this because i don't have a good mobile phone to use and my parents are not going to buy a good one for me so i can't and if i use one of my old mobile phone it's not very bright so my camera is not catching that much low light on the wall so i think i need to win one phone but i don't know i will or not but i will try taking a picture i will give in two three days ! Sorry for you inconvenience! But i assure you i you will use your i phone it will project very good quality of image!