Couldn't help, these cool exotic LED displays are just too intriguing... I could not go to sleep, I HAD to play with them !
So I wired one up on a bread board.... and I thought hey, 8 segments, that's also an ideal pretext to use one of those cool white ceramic resistor arrays as well, what a combo that would make !
... but I had to give up on the latter. Would have made for a big mess of wires and I would not even have had enough Dupont wires to wire it all up anyway !
So instead I did the more sensible thing, and used one of the SIL packages instead... plenty to chose from in 9 pin configuration.... picked a 120R one. I measured all 8 of them and I was surprised to see just how close to nominal they measured ! Some were dead on, and all others were within 0.5% !
As for the display itself, first I tried to buzz it with the DMM, to double-check the pinout diagram ch_scr gave me and.... I found that all segments were open-circuit ?!
Tried another display... same again. Reversed polarity just in case I got some common cathode variant instead of the common anode depicted in the diagram... still no joy. Weird.
So I wired the display anyway, and put a DMM in series with the lab supply to monitor current... don't want to blow my previous vintage displays you see !
ch_scr said they are rated at 20mA or so, so I targeted that. 8 segments... that's 160mA total then.
At first I got zero current, still no life in them..so I slowly upped the voltage, whilst anxiously monitoring current at the same time and... the decimal point starting glowing faintly.. then some more.... then the 7 segments starting coming on finally as well.... upped voltage to much more than I thought algebra would allow... until I got to 160mA, and all the segments were nice and bright.
THEN... Eureka moment... since each segment is composed of two half segments... that means TWO diode drops per segment ! That's why my DMM said open circuit when I tried to buzz the display ! Also why I got zero current flowing when the power supply was set at a voltage that SHOULD have been adequate.... for a NORMAL display.....
Geez, trap for young players as Dave would say !
Works all fine now, look at that !
My camera is incapable of taking a decent picture that would make justice to the display... took me 20 attempts to get the half decent pic below. Bloody camera keeps washing out everything, and it insists on seeing pink colours where me the human sees red...
Maybe time for a new camera.... no, not anytime soon, these things are expensive...
Anyway, they work fine and look nice, I can definitely use them in some design of mine at some point
Yes, the decimal point uses only one diode / element, so it's brighter / gets more current... in real life I would need to a use separate, higher value resistor for that decimal point, so that it gets the same current as the 7 segments.