build a huge 7 segments 8 digits red led display - polycarbonate sheet cut to size
This instructables shows how to make a huge 7-segment 8-bit LED display.
The purpose of this display is to display the time, date, temperature, or to use as a timer in various running races, mountain bike races, trail running races, etc (
Shows the time that may be displayed (
Time, minutes, seconds, hundred seconds).
In order to use the display, a micro-controller or digital interface is required, which is beyond the scope of the current manual.
The display can work as a stand-alone device driven by a micro-controller (Arduino stuff)
Or may be driven by a PC/laptop (
Some discrete digital logic interfaces).
Design restrictions/requirements :-
To be big enough, from 20-30 meters -
Bright enough to be visible/readable in the sun
Energy-saving light emitting devices (bulbs, LEDs)/ (
Low power consumption)-
Use viable and durable LEDs
Able to withstand harsh environments (
Some games may take place in autumn, winter, rain, hot sun)-
Keep light and strong at the same time (
It must be brought from point A to point B)-
In order to fit the roof of a normal truck or car, have a reasonable size-
It has to be brought from place to place
Hours, minutes, seconds, and milliseconds are displayed (
Hundreds of seconds)
As a timer
Temperature is also displayed (
Negative and positive)
, Local time and current date-
Separate digital pairs-
2 Separation points
Allows the reuse of segments and numbers, and separate control of points reduction and separation --
Have a reasonable cost
Involving a reasonable amount of work-
To look good according to these requirements, my option is to use a red LED light strip for 12Vdc (
These are all in the reels and you can cut the required length)
A wooden board and a wooden frame.
Connect All led using cheap network cable (
8 lines inside, full copper).
Led is connected to 7 segments and 8 digits per digit (
The 6-digit number is large and the 2-digit number is small (
These two digits are used to display hundreds of seconds)).
There is also a big minus sign in front of the first number (
For negative temperature)
There are two separate points between each pair of numbers. Tools needed: -cutter -scissor -wire cutter (
Wire welding tools are easy to use)-
Soldering iron and related tools for welding electronic parts-
Rigs and drill bits-wood saw (
Any, you need to cut wood a few times)-Paint-
Printer for printing A4 paperothers (? ! )
Materials needed :-red LEDs -
There are two reels under 12 vdc, one of which is a 5 m or 300 red LEDs (
Update 2014: you can look for LED reels with 120 LEDs per meter and the results have been improved, see another nice item here: giant double-
Digital countdown clock)-
Polyester board for constructionroofs (
First Choice for transparency
Mine is on sale, it's light brown)-
Wood for building wooden racks-wood paint -
Network cable 20 m (UTP cable)-
Sanitary silicone tube 2-
4-hot glue stick5 sticks -
Thick paper pattern for aligning line segments and numbers-6-8 A4 sheets (2 types -small and big)-
Transparent packaging tape
There should be enough plastic crosses packed in 100 tiles (
Thickness is important, so 3-
4mm is OK, or with 2, each on top of the other)-others (? ! )
Unfortunately, I didn't take too many photos while building this huge 7-segment 8-digit LED display, and I didn't intend to share this experiment, but now I realize it's also interesting for others.
For this reason, Instructure does not record every detail with pictures, some existing pictures are not the best and not the most explicit, therefore, you need to understand my English, or imagine another way to do the same.
Or just ask where you don't understand :)! Let's start!
Edit: LED stripe-> LED strips -
See the comments for more explanations. To determine the size of the 7-segment number, I first considered the LEDs.
The Led appears in reel form and is powered by 12Vdc.
I can cut the required length of the LED stripe, but I have to follow some rules :-
The minimum LED stripe consists of 3 LEDs, which is 5 cm (~2 inches)
The LED segment must be a multiple of 5 cm-
There must be 2 power cables at one end of each LED segment (+12Vdc and GND)-
The LED segment of the 7-segment number has a specific angle-
See a small 7-segment LED display and find out what I'm talking about-
There is a certain gap between LED numbers-
The point between each pair of numbers must consist of two parallel strips (5cm strips)
So there's a choice here: 3 5 cm LEDs are used for the big 7 segment display (
3 LEDs per stripe)
, Small use 2 LED x 5 cm.
To make the 7-segment digital paper pattern, I downloaded the 7-segment display image from the Internet and enlarged it to fit the length of the LED segment size of 15 cm and 10 cm.
Because I use two types of numbers (small and big)
, 2 size paper samples were created.
Finally, the big number is 33 cm high and 22 cm wide, and the small number is 23 cm high and 16 cm wide.
The paper used is A4 size, and 4 sheets of paper are put together with a packing tape;
These are printed at home with my personal printer.
After that, cut some cuts/holes at each end of each segment on the paper pattern to be able to mark points that fit the LED strip-
According to the size of the 7-bit display and according to the distance between the displays, the polycarbonate panel is trimmed.
Polycarbonate set 2 m long and 1 m wide
Using the cutter for operation, I cut two identical parts, 50 cm x 200 cm.
Be careful which side you want to use inside and outside.
Now on the part used as the interior, peel the shield from the polycarbonate panel.
I mark points on a piece of paper that I cut before-
Place the pattern on a polycarbonate board and mark the point with a permanent mark (
Like Sharpie or something like that).
I double checked if my mark is correct and things look like a pattern for a huge 7-segment LED display --8 displays.
The next step is to take the LED reel and cut the stripes according to the length I need.
This is done with scissors.
At the mark on the LED strip, I cut the length.
For a large LED segment I cut every 15 cm (
3 groups of 3 LEDs or 3 lengths 5 cm)
For a short section, I cut 10 cm per cut (
2 groups of 3 LEDs or 2 lengths of 5 cm).
The small dots between the large minus sign I cut from the 3 groups and each pair of 7 segments show what I cut from the 2x3 cm LED stripe.
I bought a network cable of 20 m, which is full of copper wire.
I stripped the gray insulation from the cable and 4 pairs of wires were accessible.
I put each pair of lines with a drill (cut 5-
6 m once, unlock them)(
Like this guy did on this clip: I got a lot of wires in this way, 8 different colors.
I cut the equal wire length and stripped the end of each wire length to prepare for welding.
For each LED strip I cut in the previous step, 2 wires were welded: 12Vdc and GND.
LED separation point (
Those between each pair of numbers)
Because 2x5 cm bars need to be parallel, the welding method is a bit different.
After that step, I connected a lot of LED bars at one end (
But there was no photo taken at that time, sorry).
The LED stripe has a nice feature: The tape is on the back.
Just remove the paper strip and the LED strip can stick to the surface in a very convenient way.
On my led it can see the 3 m logo and I think it is a high quality adhesive.
In the previous steps, I marked the polycarbonate panel to know where to glue the tape, so I glued all the tape to the polycarbonate panel based on the previous mark.
Since I have 7 LED clips on each number and 8 LED numbers, because I have 3 pairs of LED separation points and negative numbers, a color scheme is needed.
In addition, for future use, it is necessary to control the separation of each segment, number, each pair of separation points and negative numbers (
By way of reuse, of course).
I think I have to create 3 cable buses :-a segment bus -
Line 7-a digit bus -
8 lines of numbers-
Minus 2 lines, dividing 6 lines-----------
Means 23 of the 3 buses using 3 network cables (
8 lines each, 3x8 = 24 lines).
I took the 3 m cable and stripped the cable gray insulation on the total length of about 2 m, I kept some insulation at the end outside the pc panel.
The bus is assembled on a polyester board with hot glue.
I created this color schematic to easily assemble LED clips onto the bus (
According to the color schematic, on each bus line, I removed the insulation on 3mm at the point where the LED wire was in contact with the bus wire.
I weld the LED stripe wire to the bus wire.
I did this for all the LED strips and every bus line (
7 segment X 2 line X 8 display = 112 solder joints).
After each solder joint, I check if the LED is on and if the current is similar to the reference LED strip (
To ensure that the solder joints are doing well ~
Avoid cold spots). (
I didn't take pictures at the time at this step, sorry)
Because there are too many wires, some are not insulated (
Remember, I removed some insulation to weld them)
, All of which can apply some mechanical tension on the LED light strip and force them to bend instead of staying on the polycarbonate panel.
That's why I use hot glue (hot melt)
In order to keep the wires in place, and also to insulate some of them.
The plastic gasket of the tile is used to ensure the gap between the 2 polycarbonate panels-
In the end, it's like a sandwich: a polycarbonate on the side and a LEDs in the middle.
I don't want the polycarbonate panel on the top to come into contact with the LEDs.
This is done with hot glue, and for each point 2 shims are glued to one.
I checked again and the LED light strip can be lit with a bus wire.
It is important to check this as in the next steps I place another polycarbonate panel on top of the LEDs and seal the assembly. (
Again, there is no image for this step)
Using sanitary silicone and silicone pistol/gun, I drew a profile on the LED polycarbonate panel.
I make sure the thickness or sealant is thick enough to fully seal when another panel is placed on top of the sandwich.
Remove the extra silicone and lay it on the side of the sandwich.
The secondary seal profile is applied on the outside and is extended across the entire edge of the panel.
If you look from the side and the outline of the polycarbonate panel is like a small pipe, I suggest sealing them may affect transparency if water enters.
Let silicone treat for about 24 hours.
After that, I cut the corners of the panel at 45 degrees.
After assembling and sealing the polyester sandwich, I measured the size of it, designed the wooden frame and asked someone to build it for me.
I'm pretty sure there are other ideas for making this framework (
From aluminum, PVC, etc).
After I got the wooden frame, I drilled the hole and took out the cable.
After that, I applied the wood rack to two layers to make sure it lasted longer.
The wooden frame is 206long, 5 cm long and 55 cm long, and it has a "L" profile to fit the polycarbonate sandwich.
Also, to make the frame strong, I put a threaded metal rod M4 in the middle of the frame (
The wood is elastic and the sandwich may fall off the wooden rack).
There you can see the protective foil on the polycarbonate board, which is on the back of the display and is not directly visible.
I tried to peel it off, I cleaned up the front that the audience could see, but it was hard and finally I gave up another face.
It was very direct and I used some parts of the metal "L" shape and some small wood screws. The metal "L"-
S was bent with the help of hammer and vice hammer
See images for more information.
These parts bring the polycarbonate panel close to the wooden frame.
Also, in order to have some hanging points, I used some hooks and some small card splitters (
For visibility, the display must be hung at a higher point).
Here's the final result of the huge 7-segment 8-bit LED display: some facts :-
Total number of red LEDs: 525-
8-bit, 7-segment red LED-
Total length of LED stripes: 875 cm (
5 m 3, 75 m reel from secondary reel)-
Total current when all led is turned on (at 12Vdc): ~2 amps -
Finished LED Panel Display size: L 206, cm x h 55 cm x t 6 cm-
Weight of the finished LED panel display: on February 2015, when I posted this, I was not ready for the schematic.
During this time people asked me how to use it.
I think the internet is full of examples of microcontrollers that use 7 digits, so this should not be a problem.
The problem may be that when the micro-controller is at 3, 3 or 5 Vdc, my monitor is powered at 12Vdc.
Therefore, it is necessary to display and 3,3-in 12Vdc-
5 Vdc micro controller.
In order to reuse segments and numbers, you must control each number and each segment, and you need to control positive and negative numbers (ground)
12Vdc power supply.
Here is the schematic I put together, which must be extended to all numbers and each segment as follows :-
The T1/Q1 section must be extended to all 8-bit numbers as the display has a common anode-
The Q2 section must be extended to all 7 segments because the display uses 7 digits and the cathode is separate (
That's how we control every number)-
Point and negative can control what we want (
I recommend connecting the anode directly to 12Vdc and using the Q2 part of the schematic (less parts))