i want to drive my nixie clock with mpsa42, but i am confused about wiring diagram. I found one with Base resistor and one without it. From some sources i found that mpsa42, is digital BJT, but from its datasheet it´s not very clear for me Link to Datasheet of mpsa42: https://cz.mouser.com/datasheet/2/258/MPSA42_7eMPSA43(TO-92)-1626582.pdf
The MPSA-42 is NOT a "digital" transistor in the sense that that is normally meant.
It does not include a base resistor on the package - this must be provided externally if required.
A base drive resistor will be required in all common emitter circuits.
Please provide a copy of your circuit and / or a link to the circuit you intend to use. Usually the MPSA42 emitter will be grounded, the base will be driven via a resistor and collector will connect to a positive high voltage load.
Any BJT with a base drive resistor becomes a "digital transistor".
Any FET is a "digital transistor"
Here is a Digikey list of FETS with Vds >= 300V in 10 quantity.
The lowest cost AO3162 is rated at 600CV at 34 mA for $US0.28 in 10 quantity.
The IDP50R3KOCEA... is rated at 500V at 1.7A and cost $US0.35 in 10 quantity