November 24, 2010
about 3 years ago
The quality of these displays is very marginal. They work and they light up, that’s fine. I ordered 13 count at the end of 2010 and they were delivered as shown in the pictures here – with a beige PC board and red segments.
I ordered 13 more to make another instance of the same project in May of 2011. I received 12 boards which were black, but had the faces poorly painted white. The 13th board was black without any white paint.
Most of the vertical segments look like they have been exposed to too much heat because the lens plastic is wavy and rippled.
These are hugely popular – everybody loves big, bright displays. I hope SparkFun can put some pressure on its supplier to get the quality control together. There’s just too much variance.
about 4 years ago
No, there are no part numbers visible on the segment bars.
Yes, still true. The board hasn’t changed to a modular design, and the segment bars are still brittle, and they’re still sealed with epoxy.
I used some controllers from itsdisplays.com and my project is going well.
This product listing is very poor; tons of details are missing. Let me try to fill in the blanks. I’ll also make a few notes about problems I found with the product. I’m sure those notes will make me sound a bit negative, but it’s really no big thing; the displays work great despite their rough edges and it’s easy to make a fun project with them.
First, they’re not 6.5 inches high. The PC board is almost 6.5 inches tip-to-tip, but the actual display is about 6 inches high. The tolerances of assembly are incredibly poor. The data sheet says that the listed dimensions are within .2 millimeters. I bought 13 displays, and received them all with the same manufacture date. They varied in size by more than 3 millimeters, and the position of the display on the board – and relative to the mounting holes – varied as well. This made mounting the displays in a straight line pretty touchy. Further, some of the individual segments weren’t mounted flush to the board and visibly angled.
A #6 screw fits fine in the mounting holes. M3.5 should work, too, but that’s not what I actually used. There are three holes for screws. Two are 1.5 inches from the top of the board, and the other is two inches from the bottom main edge (not the card edge) of the board.
There’s no hope of using any kind of edge card connector as the card finger is not a standard width and the traces are irregularly sized and spaced. The product would be vastly improved if the displays had any landings for through-hole connectors, either single- or double-in-line, so terminating a ribbon cable to a header or even just soldering wires would be easy.
The forward voltage of each segment really is 12 volts. The decimal point has fewer LEDs, and it turns out there is a tiny SMD resistor on the display’s foil side to limit current for that segment. It is almost comparable to the rest of the segments, but the intensity isn’t exactly identical.
If you drive the displays with a 12-volt source, you’ll probably be OK with duty cycle. At continuous current, you’ll want a 110-ohm current limiting resistor. Or, you can use a constant current source–perhaps one is built in to your controller board.
I hope that helps!
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