The LEDs should pulse ~25 times/sec (similar to videos frames). Shop’s name will be only a straight vertical line of white light (no RGB) until the viewer moves the head → readable text = shop name.
I plan using high power LEDs that should be mounted behind a darkened or blurred surface of glass placed in a weather-proof frame.
The vertically orientated LED-line should be placed on both sides (viewed while walking on each side of the pavement).
The sign’s measures should be approximately 100 x 5cm (40 x 2 inches).
As a none-electrical engineer i’d be very thankful getting some useful hints and advices about suitable components to use (Power-LEDs, controllers, boards, …).
I have to say that’s a unique take on POV displays, where usually the motion is on the display end and not the viewer end. Reversing it is a stroke of inspiration ! As to whether that’ll work as an advertisement for a business … it’ll be interesting to see.
So how many LEDs and across what vertical distance were you thinking about ? My initial thought is that this is simple for any micro-controller plus LED driver circuitry to do. The governing constraint is the update time for all the LEDs. And so there are existing commercial LED strings that may or may not work depending on how many LEDs are in your vertical strip.
The „shop sign" should be a slim and aesthetically simple looking bar, that only should show a solid line of white light.
It’s not about showing the big advertisement-muscle. It’s more about generating a discreet and hopefully kind-of-interesting appearance. I want to build and use it for my little studio/gallery here in vienna, austria.
I guess that 50-80 (?) LEDs vertically aligned on a bar with a height of 1 meter (40 inches) should „draw" a nice solid and continuous line of LED-light. The gaps between the SMDs should be rather small. And yes I agree, that the update-time could be some bottleneck.
Moreover i am kind of flexible depending the height of the LED-Bar. It would also be fine for me to reduce the size of the bar to - let’s say - 60cm (24 inches), if this would reduce the complexity of the project.
There are strings of LEDs, that come 60 LEDs/m and even 144 LEDs/m, that are easily controllable by an Arduino. Looking at the latter … the LEDs are controlled individually by an IC “melded” to the LED. A single serial line then carries the data from the Arduino to each LED. Each LED uses 24 bits to set the brightness of it’s red, green and blue constituents. The data rate is 800 kHz. That all means that it takes 144 LEDs *24 bits/LED / 800,000 = 4.32 msec just to send the data to the entire string. If calculating all the values took 1 msec (very likely less in your case) then that’s 1/0.00532 = 187 Hz. You can change the string 187 times per second.
Normally these strings are too slow to be used in the usual POV displays, where the string has to move. But if you only want on/off control of each LED, even if you want on/off control of the individual R, G and B components …then it could work … if your 25 frames/sec is correct.
pinzo:
I think to have enough resources. which board would you recommend, that will do the job easily? i am thankful for each hint.
best, r
A Mega has a lot more I/O pins than say ... an Uno. But you only need 1 output pin. A Mega has 4x more Flash memory to store larger programs but I don't think that'll be a concern in your case. Same goes with SRAM, to store more temporary data. In short an "Uno class" board should be sufficient, if all you're planning to do with it is the above LED strip.
A Mega will surely work just as well, it’s just more $$ and space w/o any real driving need that I can see. But buy it if you have plans for expanding the project.
Correct, for now the plan is only to use 2 LED-Strips, that will display an identical signal. I’ve already talked to a friend of mine who will give me support and teaching to bring this little “project” on its’ way. thanks for giving me all these advices. I’ll post some news, as soon there’s some progress.