CowJam:
Federico:
Are the Mps42A switching the anode?Why do you want to switch the anode?
I am getting a bit confused.
You guys said that optocouplers are not necessary if I am going to multiplex the nixies.
In your setup aren't necessary because you hook up the anode and use a 74hc595 with two 74141 for 2 nixies. So if you have 6 nixies you have 3 595 and 6 74141, at least.
But, if you, for example, connect all the cathodes of your nixies together to a single 74141 you need to switch the anodes with the 595, in high voltage multiplexing them and using persistence of vision. I supposed that this was the meaning of the transistor, for dividing the high voltage of the nixies from the low voltage of the IC's and the arduino...
Fede