hi there,
can anybody tell me where to find a datasheet for this specific bargraph?
a.imagehost.org/view/0807/IMG_2345_1
(sorry i can't post links.. just add http...)
unfortunately i can't tell you which brand this is, but it has this specific pin-assignment.
thanks, atsch
I can't see the photo, but look here for the types of bard display:-
Pin outs are normally common.
I can't see the photo
So much for socialised health care ;D
But back to atsch's problem...
Usually a google search would turn up links to datasheets, but it didn't this time.
So, it's time to reverse-engineer.
It looks like there are 15 pins on that display, and they appear to be symmetrically arranged. Since there are 12 LEDs (I think: the picture doesn't show the face clearly), it's very likely that one is common (possibly cathode, but more likely anode, so the segments could be directly driven from TTL), 12 are connected to individual LEDs, and a couple are unused.
The LEDs are probably rated for about 2V at 20mA, like most green LEDs of that vintage. So, you need to get a 5V power supply, put a resistor of about 300-500 Ohms in series with it, and just start trying combinations of connections until something lights up. The resistor should keep you from burning out the LEDs, and reversed connections at that low a voltage won't hurt them.
It shouldn't take too long to work out the pinout for yourself.
One other tip: since the pins are symmetric, if the center pin isn't the common, you'll probably find that its mirror-image "twin" is also common, since the display appears to be designed so it can be inserted either way without damaging it.
Have fun, and make sure you put your notes on the pinout in a file that'll get backed up, because you'll almost certainly eventually lose them if you just scribble them on paper. :-[
Ran
So much for socialised health care
Hey everyone in the UK is laughing very loud about what you guys seem to believe about our health system, no one here would swap. Well you always get the odd nutter who will say anything to get on the TV but no real people.
thank you both very much for your help.
it seems that the LEDs are in groups of four with a common cathode for each group.
i just find it a bit strange that there are different spacings between the pins which obviously don't have anything to do with the location of the common cathodes..
atsch