This is half a quick note for my own reference, half a note for anyone else who might happen across one of these, and half a note to let you know, dear reader, that I’m not dead…
The NSN66 (and, I suspect, very similar NSN66A) is a very old-school six-digit seven-segment LED display manufactured by National Semiconductor back in the early 1970s. I’m not sure what they originally found use in, probably radios. Obsolete for several decades, the global electronics marketplace is such that you can find them new, today, without a whole lot of difficulty, and without paying too much money.
There are several places online that sell ‘em, still, and with a bit of searching you can even find the datasheet, which will tell you it was introduced around 1973, is a 1/8th-inch common-cathode red GaAsP display, that each segment is 3.0V, and draws an average 5ma, with the max rating per segment being 60ma, a pulse width of 10ms, and a viewing angle of +/-60 degrees off-axis.
What nobody seems to tell you is the pin assignments.
Well, if you were looking for that, here you go…
The display module has a row of seventeen holes on 0.1″ centers. Holes 0, 10, and 16 are unconnected.
With the somewhat standard notation that the top is segment A, the top-right is segment B, the lower-right is segment C, the bottom is segment D, the lower-left is segment E, the top-left is segment F, and the centre is segment G, the pinout, viewed from the front, is:
NC | C | 1 | DOT | 2 | A | 3 | E | 4 | D | NC | G | 5 | B | 6 | F | NC
(As the datasheet points out, on the NSN66, there’s only a dot on the fourth digit on the NSN66. I’m not sure if the NSN66A has a dot on every digit or not.)
These are very neat, very small, extremely retro displays well-suited for all sorts of improbable projects. The weird single dot limits its functionality in many regards, but, well, there’s probably a reason they’re plentiful… and cheap…