Have you ever seen something like this alongside the road?
That thing measures the speed of an approaching vehicle and displays it to the driver. It's safety thing, not law enforcing. Anyway, I'd like to install one of those things on the model railway layout (we also have tiny cars driving around). The problem is the digits have to be really tiny - under 4 mm.
Most commercially available 7 segment displays not only have significantly larger digits, but are also quite thick, while this display should look more like a thin panel and less like a cube. (The electronics can be mounted under the road, so there is no limitation on that part)
Does anybody have any experience with something like this?
I was thinking of soldering 0402 SMD LEDs in that pattern and just running thin lacquered wires through the post the panel would be mounted on.
The problem is the size of the LEDs. For the whole thing to look realistic and more or less to scale (1:87), the digits would need to be less than 4 mm tall and that calls for tiny LEDs I've never worked with before and I'm not sure I'd be able to make a PCB for that packaging. My idea is to glue the LEDs upside down to a transparent foil or even a cover slip (that thin glass plate for microscope slides) in their final positions, and then carefully solder the contacts, run the wires through a hollow post on which the panel would stand and have all the electronics under the road.
Does anybody have a better idea? Any suggestion or comment is appreciated.
John, the digit size of those displays are ok, but there is quite a bit of extra "meat" on all sides, bringing the entire thing to a rather large sized box.
CrossRoads, yeah, that's pretty much along the lines of what I had in mind myself.
But my question was more aimed at the production method, rather than design, if you understand what I mean.
Buy the boards from iteadstudio, apply solder paste, place the LEDs with tweezers, reflow in an oven.
Solder wires to pads on the back.
Small, but do-able.
You might find a 128x64 pixel OLED display is suitable - certainly thin (but connections can
be tricky!) You'd also need to find a 7-segment font for it or generate graphics.
I need only one or perhaps two of these displays so ordering the board seems a bit of an overkill.
An OLED display would also be a bit too large, I believe (I'm talking about the entire package).
Well, I suppose I'll just get some LEDs and start experimenting.
