datasheet
this is part of datasheet from Vishay. I want to do a footprint based on this picture, but can't figure out the dimensions…
The space between the pins is described two times: is says 0.220 (5.6) and 0.180 (4.6) at the same time. I just don't get it. Thanks for help.
When it comes to these sorts of logic ICs, if you match the part number you'll match functionality. So, a 74HC595 from NXP should 'work' the same way as a 74HC595 from TI. The pins are given different nomenclature by the manufacturers, but they do map 1:1 between the ICs.
If there were a functionality difference, then there would be a corresponding change to the part number:
Consider the difference between a 74HC595 and a 74F595 - both do the same logic function, but the underlying technology of the IC is difference (HC is high-speed CMOS, F usually refers to Fast which generally implies Schottky construction). There can be differences in timing and logic voltage levels as you change technology.
Consider the difference between a 74HC595 and a 74HC596: the 595 is what you're using (8-bit shift register with output latches, three-state parallel outputs) whereas a 596 is slightly different (8-bit shift register with output latches, open-collector parallel outputs).
Of course, even with the same number, there likely is very minor variations between them. The fundamental functionality and speed will be compatible and unless you're really pushing the limits of the IC, you should be able to substitute with confidence. (That being said, always test!)
The timing diagrams should clear things up:
As Dave said, you don't have to actually run the tube in a real circuit to get the visual effect. All you have to do is power up the heaters.
Your particular tube actually is two tubes in one package and has two heaters. Each heater is 6.3 V. You can put 12.6 V accross pins 4 and 5, or 6.3 V accross both pins 9-4 and 9-5. In the latter case, you connect one side of the 6.3 V supply to pin 9, and both pins 4 and 5 to the other side.
Don't worry about the exact voltage that much. These things were intended to be run directly from a 6.3 V output winding of a power transformer. It will be OK with variations of this 6.3 V due to input line voltage variations. Get a "6.3 V" transformer intended to run from whatever power you have in your location and the tube will be fine.
You do have to make sure the transformer is rated for the total current of all the heaters together. For example, if you are powering 5 heaters that all take 6.3 V at 300 mA, then the tranformer output must be rated for at least 1.5 A.
Best Answer
The dimensions are maximum and minimum. Basically the actual dimension will be somewhere between the two.
For your footprint I would take the dimensions for pin locations to nominally be the mid point.
As pointed out by @Trevor in the comments, for the size of the holes, take the maximum dimension and add on any drill tolerance to ensure the holes are large enough.