footprintnixie
I'm a beginner of electronics. I have several IN-12A nixie tubes. I want to mount the nixie tube on the PCB. However, the position of the pin in the datasheet is out of the position of the pin in the nixie tube.
Also, since the pins are slightly twisted with each other, adjusting the library to one nixie tube can cause problems when replacing nixie tubes. How do I arrange holes to design a library that fits all IN-12A Nixie tubes?(I use the pins of D'SUB instead of Nixie Socket.)
The nixie tube is essentially the same as a neon bulb with multiple cathodes. The wire cathodes are shaped into the numbers 0 to 9. To turn the electrode ON you need to supply a high voltage (of about 170 Volts DC)to the common ANODE (the see through grid). This will be through a current limiting resistor to give a current of about 2mA. When 'lit' the anode voltage will drop to about 140V (the maintaining voltage). You will need to check the actual figures for your chosen nixie tube.
To light the cathode you will need to switch it to ground (0v) through a transistor or other suitable switching device.
This could be done by switching each cathode with a single I/O line (through suitable transistor etc.) but with three nixie tubes you would quickly run out of lines.
This is where the 74141 comes in. It is a BCD decoder 1 of 10 outputs designed to switch the cathodes of the nixie to ground. This requires FOUR I/O lines per digit (nixie tube). This chip also ignores non valid numbers (1010 - 1111) and blanks the display.
You could drive this chip directly from the arduino OR you could add some 4 bit latches between the arduino and the 74141 avoiding the need to tie up the I/O lines or multiplex the display.
Health and safety warning - High voltage hurts and destroys arduinos if you're not careful.
It can't work without a ~5V Vcc on the chip, and a ground.
Since you say it was removed from a (presumably functional) instrument, let's assume it did work.
So, perhaps you simply can't see the power connections or they are no longer present- they are under the chip, or it is a 4-layer board with ground and power planes, or some of the parts you removed were effectively or literally shorts to the power rails.
Edit: Also note that these chips (both the 74x and the Russian one) are among the few TTL chips (as is the 7490) that don't have the power pins in the corners- they're pin 5 (+5) and pin 12 (0V).
Best Answer
PCBs and tubes don't mix well for that very reason the pin tolerances of tubes are too high and bending pins of a tube isn't an option either.
So the answer is to use a proper tube socket. These are made for that purpose, their individual contacts wiggle inside the socket housing to account for the manufacturing tolerances of the tube.