The goal is to spell out one or a few words with LEDs. I am thinking of a bunch of LED lights that spell out the word(s). Every second or so, the LEDs should switch off for maybe 0.1 seconds to help with attention. Your advice is solicited here as to what will be readable and grab the most attention. They need to be fairly bright to see outside.

I am thinking of a 555 for the timer and an electric switch to directly drive the LEDs. All my searches for electronic switches come up with manual light switches. What do you suggest and how might it be wired? The power will be a battery pack. Two hours or so will be sufficient. Maybe four hours so it does not get too depleted before charging again. Seems like a proto board cut down to size will be the best option for mounting the 555 and switch.

I can solder and wire well. Your advice please.

Thank you for your time.

 

Let's get down to the details.

1. How tall is each character?
2. What color LED do you want? This is important because the circuity depends on the voltage and current of each LED.
3. What is the largest single word to be dislayed?
4. Give us an example of a phrase you want to be displayed. Choose any phrase that is not confrontational. For example, it could be "SEND ME YOUR LOVE".

 

Wow, what a quick response.

Size: about 3 inches high and maybe 2.5 high wide. That seems to be visible from about 60 feet easy. Each sign will be custom made.

Color: Did not know that matters. Red. But maybe something else if better. Or maybe a two color LED and have it switch colors every second or so. But that might be too much. Suggestions? We will carry the sign on the sidewalk next to street.

Largest Word: Lets go for 10 characters. Need simple words.

Example phrase: JOIN US or the word DEMOCRACY. Only one or two words to grab attention, the remainder will be printed as usual. Something like 8 lights high and wide. I will figure out the maximum count needed and letters that need fewer lights will have those hidden behind the poster to make things simple. Letter M needs about 8 high and maybe 6 for the two interior strokes, 28 lights, make it 30 for each letter. That is 300 LEDs. Suggestions are solicited.

Maybe the lights for each word should be connected in series, each letter in parallel. That might make easy to troubleshoot a bad light.

Wonderful questions. Thank you.

 

Have you considered using LED tape?
https://www.amazon.com/RadiantFlux-Dimmable-300Leds-Bedroom-Flexible/dp/B0C96KQ9VQ/ref=sr_1_2_sspa
This can be cut and easily formed into letters. You might cut strips and wire them together with small gauge wires, forming the letters you wish.

What is your power source? Since you're talking about signage it's likely you're using battery power. For such a project you should consider Lithium Ion batteries.

 

Largest Word: Lets go for 10 characters. Need simple words.

You'd be better off using a single board computer like a Raspberry Pi Zero W.

For 10 characters, you'd need 10+ LED displays (or their discrete counterpart). Words/phrases don't matter because you'll implement support all letters and numbers.

 

Example phrase: JOIN US or the word DEMOCRACY. Only one or two words to grab attention, the remainder will be printed as usual.

Something like 8 lights high and wide. I will figure out the maximum count needed and letters that need fewer lights will have those hidden behind the poster to make things simple. Letter M needs about 8 high and maybe 6 for the two interior strokes, 28 lights, make it 30 for each letter. That is 300 LEDs. Suggestions are solicited.

Maybe the lights for each word should be connected in series, each letter in parallel. That might make easy to troubleshoot a bad light.

Wonderful questions. Thank you.

Not sure what you mean by all of the above.
I would not design character displays like that.

I would start with each of the 26 letters of the alphabet. What is an efficient way to display every character from A-Z?

Here is an example:



This shows each letter occupies a 5x7 array of LEDs, i.e. 35 LEDs per character.
Now you design a single character as a module. All modules are then connected to a single 1-wire network, connected to a master module that sends the message and does the timing sequence.

 

Another way is a module of just 7 LEDs high. The MCU controls what is displayed on each module.
Now you need 50 such modules. With this design, you can have smooth scrolling, flashing, etc.
Again, this is very doable.

In terms of power requirements, assuming 20 mA per LED and 20% are on, that is 75 x 20 mA = 1500 mA @ 3.3 V which is about 5 W.

 

Have you considered using LED tape?
https://www.amazon.com/RadiantFlux-Dimmable-300Leds-Bedroom-Flexible/dp/B0C96KQ9VQ/ref=sr_1_2_sspa
This can be cut and easily formed into letters. You might cut strips and wire them together with small gauge wires, forming the letters you wish.

What is your power source? Since you're talking about signage it's likely you're using battery power. For such a project you should consider Lithium Ion batteries.

Did not know about LED strips. That is workable. Thinking about the reply from MrChips.

 

I'd multiplex the LEDs and drive a column at a time so that, at most, 7-8 would be on at one time. I implemented a 5x7 display, but 8x6 is also common. I made a single digit scrolling clock display that could also display arbitrary messages. I used a RPi Zero W and needed fewer than a dozen outputs. I plan to expand to 8-10 characters, but that wouldn't increase the number of outputs needed.

The same RPi is also driving a 4x4x4 LED cube.

 

Did not know about LED strips.

You'd be better off using a full matrix for each character. That would give you maximum flexibility.

The method @B-JoJo-S is suggesting would only work for fixed messages. It sounds like you want multiple messages, so fixed letters is a no-go.

 

No sure what you mean by all of the above.
I would not design character displays like that.

I would start with each of the 26 letters of the alphabet. What is an efficient way to display every character from A-Z?

Here is an example:

View attachment 361702

This shows each letter occupies a 5x7 array of LEDs, i.e. 35 LEDs per character.
Now you design a single character as a module. All modules are then connected to a single 1-wire network, connected to a master module that sends the message and does the timing sequence.

The suggestion from MrChips looks wonderful. The price for most is several hundred dollars. Found a cheaper one that is 17x4 inches for $47 and 33x4 inches for $70 and the weight is 2.1 pounds. That would be OK to carry on a poster.

ACU BEST.COM, LED sign

And the plain text for the link: https://acubest.com/products/led-inputtable-sign-with-border-u-65a-1-u-65c-1?variant=31166478516318 (if you are worried about fake links)

The web page does not mention how to control it. Looks like it requires an Arduino or some other device microcomputer. I presume there is a serial port between sign and computer. Hopefully USB. That web page ad did not specify. I suspect the battery and CPU would be on a belt around my waist with a USB cord from there to the sign.

I was thinking a string of LEDs for each letter and cut holes in the sign for each letter. This seems to be much better.

 

A critical key part of the project is "What is your power source?"

 

Here's a video of the single digit scrolling LED clock I made:
Single digit scrolling clock

 

A critical key part of the project is "What is your power source?"

Started with just a battery pack on a belt around my waist. Now it looks like a battery pack and CPU. But maybe something hanging from my shoulder would be better. With the referenced light strip, how much battery would be needed to two hours, maybe four?
I can probably program an Arduino to do this.

 

I can probably program an Arduino to do this.

I think it'd be difficult to have variable messages with an Arduino. You run a single program so changing messages would be problematic.

The display I showed has to be restarted to change the displayed message. For Arduino, a new program would need to be created.

 

I would suggest something like Arduino to drive the display.
The serial communication can be just three bytes to keep it simple:

<START> <ID> <DATA>

You can add extra error checking but probably not necessary:
<START> <ID> <DATA> <CHECKSUM> <END>

<START> is one byte that will never be transmitted, e.g. 01010101 (binary)
<ID> is the module address, any byte from 1 to 255
<DATA> is 7-bit data
In all cases, the extra bit can be used for parity check.

 

I think it'd be difficult to have variable messages with an Arduino. You run a single program so changing messages would be problematic.

The display I showed has to be restarted to change the displayed message. For Arduino, a new program would need to be created.

With Arduino, you can have many messages stored and the desired message can be selected by pressing a single pushbutton.
Or you can have 4 or 8 messages selected by 2 or 3 DIP switches.

 

The goal is to spell out one or a few words with LEDs. I am thinking of a bunch of LED lights that spell out the word(s). Every second or so, the LEDs should switch off for maybe 0.1 seconds to help with attention. Your advice is solicited here as to what will be readable and grab the most attention. They need to be fairly bright to see outside.

Please clarify: Do you want one sign that changes to different messages or the impression I got was you wanted a sign that says one thing and one thing only while another sign may say something different?

 

Please clarify: Do you want one sign that changes to different messages or the impression I got was you wanted a sign that says one thing and one thing only while another sign may say something different?

My original plan was for one word or phrase to be shown all day. An Arduino could do one, or several. The difficulty with several is getting the data into the Arduino, so I think that dynamic changes would be out of the question. For now, program one word or phrase at home, then go out to display it.
And, so far, I am presuming the sign has a USB port.
Or maybe use a second port on the Arduino and have a keyboard available to plug in, change the phrase, then go back out on the street. That would need significant extra thought and programming. I will go with the single word or phrase for the first working version.
HOWEVER: The ad for the display does not provide any information about how to set/configure the display. Or maybe if it accepts the word/phrase and keeps it through a power cycle. Still looking for that information. A user manual that is.
PS found the owner of the ad pages sent them an inquiry. That may take a few days.

 

Many possibilities exist.
You can program any number of words (up to a limit) at home. Then you can select which word you want on the road.

If you want to get fancy, you can alter the word on-the-go via bluetooth from your smart phone. This takes a little extra work to implement.