On Apr 22, 2020, at 9:39 AM, '[email protected]' via neonixie-l <[email protected]> wrote: > > I would say whichever is cheaper, keeping in mind that nothing is cheaper > than free from the junque box. I used the floor sweepings (advertised as > npn 300V and 10W) from Poly Paks, and none of these have failed yet. I did > have one genuine Motorola MPSA92 fail after 40 years of service. Just make > sure you are driving your transistors into saturation. Obviously TO92 is > smaller than TO220, and this might be a factor in your application.
The perfect example of this is driving an IN-13 vs an IN-9. The former will work with an MPSA42 but the latter requires an MJE340 because of the higher current. It's well known that the bargraph tubes work more reliably if they're strobed; all of the circuit examples in Russian data sheets for the IN-9 and IN-13 use a half-wave rectified 220V mains power source. And now I finally understand a circuit modification I saw in a forum thread that has puzzled me for some time. The OP couldn't get an IN-9 (using an MJE340 of course) to work reliably using a generic barpgraph driver circuit. One of the replies added a 555 running at 50Hz driving a MPSA42 in series with the MJE340. What? How could you use the smaller trans... Now I get it. The MPSA42 was being used as a switch. DUHH. Thank you for that insight. Cue up the next great mystery of life... Terry Bowman, KA4HJH "The Mac Doctor" https://www.astarcloseup.com/ "Every kid starts out as a natural-born scientist, and then we beat it out of them. A few trickle through the system with their wonder and enthusiasm for science intact."—Carl Sagan, Psychology Today, 1996 -- 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 [email protected]. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/B30CB5AB-765F-4F1C-AC1C-8F7D176739EE%40gmail.com.
