I tested a IN-12A nixie tube. I want to use a nixie socket to use a nixie tube, but it is so expensive to buy one. And then, I found this site. So I decided to buy D-SUB. Today, it arrived. I tested the nixie tube. It is super easy to make D-SUB connector into nixie socket. Just break a metal cover and get plenty of connectors! It fits tightly into the nixie's pin.

It's perfect!  And I tested the nixie with jumper wire.

The nixie tube's condition is very good! I love this orange glow discharge.

And I drew my nixie clock's main board schematic. I'll check it one more time tomorrow and then, I'll upload it.