There are thermal considerations; the MJE340 is designed to be used on a heat sink and is rated for 20W, vs 1.5W for the MPSA42. Also, there are some differences in the safe operating area curves; the MJE340 can tolerate a bit more current at any given voltage. MJE device also has a lower Vce (sat) for a given collector current.
That robustness doesn't come for free; the MJE device has 1000x higher leakage current. So, as with any design, you have to look at all of the datasheet parameters carefully. -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to neonixie-l+unsubscr...@googlegroups.com. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/3c595f67-cc4c-4415-a305-fad9619bd3aa%40googlegroups.com.
