Introduction: LED Sign - Sequencer
I didnt use the 2N3053"s shown in the diagram as they are 7 times more expensive than the BD135"s i replaced them with.
The BD135's have higher amperage and voltage specs anyway. See specs pic's.
A 555 timer is used for the clock at around 1kHz. There is a 100K pot to vary the frequency.
This is a common 4017 sequencer circuit you see online other than it includes the extra diodes from each stage going back to every other stage before it. So all the stages stay forward biased and letters light up progressively until the word is complete, then a reset from the last stage to pin 15 and then it repeats.
There is 10 output stages on the 4017. in the WELCOME word diagram only 7 are used. For my INTERNET word i needed to use the next stage in line which is #6. INTERNET is 8 letters and WELCOME is 7 letters, so stage #6 makes up the difference. The remaining two, #9 is next followed by #11. The #9 i will add to the sequence so the word will stay on for that period of time. The # 11 i will use as a delay for one blink sequence. So the complete word will be off for one sequence. Repeat.
All the LED's are connected in parallel for each letter only. Each next letter has its own LED parallel circuit.
The 10 output stages are not in order as the pins are. To get the out puts to FLASH in order from 1 to 10 the pin order will be: 3-2-4-7-10-1-5-6-9-11. Number 15 is reset. To use say 4 outputs and reset back you would send the 5th sequence to pin 15.
The order for 4 out puts will be 3-2-4-7 then pin 10 would go to reset.
You can do a lot of different things such as skip every other pin for a on off effect ect.
BOM for sign;
- CD4017 1
- IC Socket 16 pin 1
- LED.s any color 219
- Resistors 270R 8
- Resistors 10R 8
- Resistors 10K 1
- Diodes 1N4148 50
- Transistors BC135 8
BOM for 555:
- 555 IC 1
- IC Socket 8 Pin 1
- Capacitor 10uF `1
- Capacitor .01uF 1
- Resistor 10K 1
- Potentiometer 100K 1
- A mounting board
- Many wires
- Power supply
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Step 1: Circuit
This circuit i started from is at http://www.electronic-circuits-diagrams.com/lightsimages/lightsckt5.shtml. I did modify it some to fit my needs.
This bread boarded circuit is just a test to see the operation of the circuit and to understand what could be done with it. For instance if you skip one sequence at the end of your word then the complete word will go off for that sequence instead of direct loop. If you add an additional sequence at the end of the word but do not add a additional letter then the word will be lit up for two sequence counts instead of one. It can be varied a lot. By adding additional 4017's you can make a longer word or sentence.
This is only 4 stages of this circuit. It takes so many connections from all the diodes that there just wasn't enough room on this bread board to lay it all out complete.. This is enough to see how it works and to make any modifications i may need.
Step 2: Lettering Stencil
I made my letters with Microsoft Office Word 2007. I made the letters size 550.
To add the circles onto you letter you open the INSERT tab. Then drop down shapes and choose the circle with cross hairs. Clicking on that will insert one onto your letter. Right click the insert and choose FORMAT AUTO SHAPE. Open size tab. Change height and width to size .21 which is the same as 5mm. For the 5mm LED's. I did not change the setting from Absolute to Relative. Click OK. Then copy and past as many as you need then print out each letter.
Cut the board to fit the size of the letters .Measure what ever size you need to fit your letters and cut accordingly. I do not have a size measurement for my boards. I only test fit everything and cut as needed. I only used a square for the ends.
Lay out the letters or your sign board and arrange them as needed. Tape them down or the wind might be causing you a problem. Use some kind of a sharp punch to pre punch all the holes. I actually used my Snap-On test light with the wire removed. Correct tool for the job u-no. This will be the first time you will go over the 219 holes. Several more times to go.
Then drill all the 219 holes with a 13/64 drill bit, same size as 5mm for our LED's. After sanding re-drill the holes for clean up from the opposite side. Sand again. This made the holes a perfect snug fit for the LED's. No glue is needed to retain them.
Zip file with the letters i used.
Step 3: Frame the Board
I used a 1/8" ply board. My choice of wood was not good. This board is about one step above kindling, but it was the thinnest piece i had without buying something. I thought if i used 1/2 plywood the LED's wouldn't come through the wood enough to alumnate well.
It was mandatory to put a wood frame on the back side, because the 1/8 plywood is not very strong . After i drilled all the holes and sanded i put the frame together. I ripped a 2x2 coco lumber ( yes coco lumber is as implied, from the coconut tree) length wise. Now i have 1x2 x5, 2 pieces. This frame made the plywood considerable stronger.
Then i chose flat black. Rattle can seamed a good way to go here.
Step 4: LED Time
Now we can start to insert all the LED's.
The first 4 letters I N T E have used 100 LED's.
If i was to do this again i might try to space the LED's farther apart, to use 1/2 as many or so.
All the Cathodes need to be soldered together as well as all the Anodes soldered together for each letter.
I arranged the LED's so all the cathodes and anodes were in a rows. Seamed easiest for soldering everything together.
Step 5: Make a Connection.
There isn't really a great way to do this. Its kind of a cluster any way you look at it. Some have a " flat wire " used to connect leads together. That flat wire is battery terminal connection wire used in making custom Rechargeable battery packs. So it solders and conducts really well.
I start with the first letter, all the cathodes get soldered together ( negative shorter lead ) and all the anodes get soldered together ( positive longer leads). That letter finished. Go to the next letter, repeat until all 10 letters are completed. All the grounds are connection between them by a ground bus made from the flat battery strap.
I tested all the LED's before assembly.
After assembly and soldering of every letter i tested the function of the letter powered up. I noted i had 4 LED's that were not working. 3 were in the corners where most of the leads come together. Where the most concentration of heat was. Replaced the 4 LED's, test again and good to go.
I want to apologize for some of the pictures as they were taken at night with my cell phone. The others were taken with a web cam, still not the greatest but are better than the cell phone pictures.
Step 6: PCB's
I will show you the modifications i ended up making so everything would work.
Do not build these boards as there is mistakes and are not correct!
I made this in 5 PCB's. Board 1, Controller board that has the 555 and CD4017. Board 2 is for letters I ans N. Board 3 is for letters T and E. Board 4 is for letters R and N. Board 5 is for letters E and T.
I printed out all the tracing of the boards with my inkjet printer. Then cut them out and taped them to another sheet of paper so this could be printed onto the acetate by a lazer printer. Then cut the tracings out of the acetate and arrange them on the board to fir for size. Cut the boards apart and check sizes again to make sure there isn't a mistake.
Some of you may have noticed there is 6 tracings. The sixth one is for a different project.
I have stopped using the heat transfer method for PCB's and use only the Presensitized Positive Photo Resist method.
With the heat transfer method i was having about a 1% success rate at making PCB's. Now with the photo resist method i have a 95% success rate and the quality is incomparable. Its the only way to go.
I do not use a fancy UV box only a desk top florescent light. Exposure time 10 minutes.
I put the pcb on a small cardboard box. The stacing goes on top of the pcb. A 5" x 8" plexiglass goes on top of that to the tracing firm on the pcb. I then weight the plexiglass down with two stepper motors for add weight. Dont have extra steppers around for weights, no problem just use something to weigh it down. One on each side for balance.
I have supplied the Eagle files for examples ONLY as they are not correct.
Do not build these boards as there is mistakes and are not correct!
Step 7: Assembly
I layed out the PCB boards to get an idea of the distance between them. Each board drives 2 letters so i positioned each board in between the two letters. Then the task of wiring everything up. To keep things somewhat organized and beadle to track what i am doing i used different color wires for different tasks. Green color wire for the transistor to letter. Black for ground. Red for power. White and blue for the diode connections between the boards.
I had originality thought i was going to make a power buss same as the ground bus. But i changed that idea to just wire the power direct to each board. This created another mod, sort of. I drilled the board so i could add the power wire from the previous board to the next board. Sort of daisy chain the power wires.
Video link here.
Some of this may not be very clear or described very well. If you can't understand some of my descriptions tell me and i will do my best to clarifie them.
Thanks for looking.