fadj:
If you do not understand why your single transistor circuit does not work, then I suggest you go read up on "emitter follower" circuits and then think about why they are not appropriate in this circumstance. I suggest you use the second circuit, with the two transistors, and go take or repeat a class on semiconductor devices. I would also add a "pull-down" resistor to the input of the first transistor in the two-transistor circuit, so that it can not turn on when the driving circuit is not initialized, and "floating". --- Graham == On Tuesday, September 26, 2017 at 6:59:46 AM UTC-5, [email protected] wrote: > > Good day,all. > > > I am a student who majoring in electronics and I am currently working on > my first nixie clock which will be running with Arduino, using a 74141 > nixie driver for the cathodes (common for 6 tubes) and multiplexing the > anodes. > > > > See the following picture: > > > <https://lh3.googleusercontent.com/-81Tq1LwyxFw/WcoXxYjn8cI/AAAAAAAAAAk/Ji5TxK19cTwo494NslNn5glaLamjAh-XACLcBGAs/s1600/9.26.3.png> > > > I am using a MPSA42 NPN transistor with the collector connected to > +170VDC, the base driven by the Arduino output, and the emitter connects to > the tube's anode. The problem is that the switching with the MPSA42 > doesn't seem to work (doesn't turn ON). > > MPSA42 Datasheet <http://www.kynix.com/uploadfiles/pdf2286/MPSA42.pdf> > > However,such as this picture: > > > <https://lh3.googleusercontent.com/-XmCX64HC6wc/WcoX6Ot9uII/AAAAAAAAAAo/Cd9oUBCzvqUQASjKXJ8Xn3FEyWF_4C4YgCLcBGAs/s1600/9.26.4.png> > > > > I saw some other design which used both MPSA42 and MPSA92 each of the six > anodes like it.My questions: > > > > - l What might be the reason why the single MPSA42 configuration would > not switch ON? > - l Why would the other design add the MPSA92 and whats the logic > behind using the MPSA42 + MPSA92 combination? > > PlePlease give me some help! Thank you in advance! > > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" 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/beagleboard/c56a7664-adfa-4f73-a255-8d6479315ced%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
