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How to make a LED 7-segment display with or without Arduino

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Picture of How to make a LED 7-segment display with or without Arduino
I'm going to show you how to make a 7 segment display with LEDS. Combine with Arduino to create countdown timers, simple text, and more. I like to make original projects. I searched the whole of instructables and didn't find one like this. In fact, I searched google, and did not find any results. I thought of this when I couldn't get my real 7-segment display to work! Enjoy!
It's amazing what you can accomplish with LEDs!
 
How the project works:
All the anodes of one row are connected together. There are 3 LEDs in one row. See picture. When you supply voltage to the row, the whole row lights up.
So, connecting all the cathodes together, I used Arduino to program each row to turn on and off. In the picture above, here are the rows that Arduino is turning on: Row 1, 2, 4, 5, 6, 7, 

Remember, the way instrucables is set up, the pictures come first, then the explanation. 

If you are interested in making this project, please read over this whole instrucable BEFORE you start and get confused! And, please, don't forget too look at ALL the pictures and the boxes for them. 

Here is a video of my the display using numbers. The next is it displaying the word, ALPHA.

Clip #220 from AJ on Vimeo.

Clip #219 from AJ on Vimeo.



1. What did you make?
The idea started when I was getting frustrated because I couldn't get my 7 segment display to work with one of my ICs, so I decided upon making my own, so that I'd could control it in basically any way I wanted, including simple text.
2. How did you make it?
The very first thing I did was get out my sketchbook and draw down my ideas, and how I would connect them together.
I started working on this project at 11:30 pm, and kept on going until about 4:30 A.M.. I kept on running into obstacles, such accidentally soldering the negative and positive leads of 3 LEDs together! I made it with 27 LEDs, a small piece of perf board, some basic tools, wires, and most importantly my newly-bought Arduino. I did this project by myself.
3. Where did you make it?
Well. . . I made this project all in my room, on my makeshift desk,and downstairs in our office (for programming Arduino). The more I programmed, the more problems arose, so I had to keep on running back and forth between my soldering un upstairs and the computer down stairs! I wore a path through my carpet, down the creaking wooden stairs, across the tile, over the wooden floor in my office to the computer. How did the project connect to other activities in my life? I was able to count this for my schoolwork! I aslo used this project as a show-off to Bravo, (another group in my activities, I'm ALPHA)
4. What did you learn?
  • Where do I start? I learned that I should have used a resistor for each LED, instead of one resistor
  • The BIGGEST thing I learned was how to program my Arduino!
  • I learned some more techniques about soldering
  • I also learned a little bit more about LEDs themselves
If I could do anything differently i would have bought 27 resistors and soldered them to each LED!
What am I proudest of? My success! I would have never thought it woud be such an interest with my friends! 
 
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steinie441 month ago

Where are the other 6 leds? 7 segments X 3 = 21 leds.

botgames5 months ago
Great instructable! Very informative, fun and easy to follow. Mine worked the first time! Thanks!
Enjoying Electronics (author)  botgames5 months ago
Awesome and thanks! Would you mind posting a picture of it?? Thanks!
Your welcome! Here's a picture of mine. I made more than one but this is the final one. It came out pretty good I think.
20131112_133657.jpg
Enjoying Electronics (author)  botgames5 months ago
Love it! It sure did!
Raphango5 months ago
Whoa! Excellent instructable!
I liked specially the Step 1 photo, because it is quite elucidative with the materials positioned in a way that shows exactly wich thing goes where.
Congratulations!
Enjoying Electronics (author)  Raphango5 months ago
Haha after looking up the word elucidate thanks!
elink53198 months ago
Thanks so much for the tutorial, I am a 59 year old beginner myself, with no background in electronics, only what I read, and try and to build myself. Simple projects, it is a fun hobby.
It's never too late to begin!
I admire your courage! I'm a beginner too.
It's quite a fun and healthy hobby indeed! ;)

Keep up the good work! =D
can i use a bread board so i dont have to solder
Certainly
polkijain10 months ago
will the arduino not crash with the 9v battery input(i suppose the operation range is somewhere around 5v)
Enjoying Electronics (author)  polkijain10 months ago
5v-12v. 12v is a little overboard. 5v works just fine as well as 9v.
polkijain10 months ago
great project
-few ques?- what is the use of the 1x 50k pot (potentiometer)
- will the project work without that
- can i control the letters with the pot directly(i mean without avr)
Enjoying Electronics (author)  polkijain10 months ago
1. Watch the video.
2. Yes.
3. Yes. See http://www.instructables.com/id/LEDs-for-Beginners/. After you've learned the concepts you'll be able to not use an Arduino.
polkijain10 months ago
wat is the use of the resistors?
Enjoying Electronics (author)  polkijain10 months ago
In short, to keep the LEDs from burning out.

http://en.wikipedia.org/wiki/Resistor
http://www.instructables.com/id/LEDs-for-Beginners/

Read up!
I love it!! I am going to make a clock using this I have all of the LEDs soldered already I am just trying to decide how I want to control it. I don't know if I want to use an Arduino or a PIC or 74XX logic gates.
Sweet! That's awesome! I'm glad you liked it. Be sure to post pictures of it when you are done!
faziefazie1 year ago
this is the picture of my LED 7-segment display, not so good as yours. and it still on my protoboard, I will change it to PCB printed soon :)

but, If I want to add a push button for the input and used for changing the characters, can you help me what the code should be add as an interrupt?
I'm sorry if I'm so greedy with the question, I'm just curious :|
second project.jpg
Hey nice job promad! Ooh, umm, like I said, I'm no Arduino expert. I have no idea how to do that. What you should do is go to the forums and ask about that.
faziefazie1 year ago
wow thanks for the explanation, I'll be waiting for the update step from you about 'adding resistors'. Thank you very much :)
You're welcome! Oh, and I added the resistors, see step 10!
agm881 year ago
cool
Enjoying Electronics (author)  agm881 year ago
Thanks! Post your pictures of yours!
faziefazie1 year ago
Sorry if I ask too much. But is it okay for not using resistor for each led? and just solder a 100-300 ohm resistor in series with the potentiometer? Because my friends told me that the LED gonna be frying all at once if I didn't put a resistor for each row/led. I'm so confused.
Hmm, very good question. Your friends are pretty much correct. I had the same question you had. You can see it here http://www.instructables.com/answers/Why-waste-the-resistors/

This is from steveastrouk

". . . LEDs have what is called a positive temperature coefficient. If they get hotter, they pass more current. In a parallel chain, one will get hotter and steal current from the others,which will get cooler, and give more current to the hotter LED which will get hotter- and so on. . . "

If one (or worse, several) LED(s) are getting an too much current, it will die, leaving you sorry you wasted 27 LEDs and a bunch of soldering. At the time I didn't know this, but I'm going to be adding the resistor step here shortly. (so I don't look like a dumbo) :D
faziefazie1 year ago
Is it possible If I want to replace Arduino with IC micro controller, how can it be works? can you tell me please?
Proma, I'm really sorry, I have no clue about other micro controllers. What you can do is ask a question on instructables forum, and post a link to my instructable, and ask if you can do it.

Erfunden1 year ago
That is pretty sweet! Would it be possible to build a 16 segment display similarly? Could an arduino handle that?
Enjoying Electronics (author)  Erfunden1 year ago
Wow, I just got finished reading about using Arduino's analog pins yesterday!
Ok, here's what I found.
7 segment display = 7 pins. 16 segment display = 16 pins. The Arduino Uno only has 13 digital pins. But, you can set up Arduino's analog pins to work as digital pins. Arduino Uno has 5 analog pins, and making those work as digital, thats 13 + 5 = 18. Yes, you could make a 16 segment display. Interesting thought. I might have to try that!

Here's a link for more reading.
http://arduino.cc/en/Tutorial/AnalogInputPins
Check out 74hc374 or 74hc164 or 74hc595 or similar chips. They can be used to expand your outputs.
Enjoying Electronics (author)  ray741 year ago
Oh yes, I have one of those chips, I just don't really know how to use it :D
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