Is it possible that those russian 74141's were both from the same bad batch? I've made a lot of clocks and only ever had one fail on me (it failed the same way as you describe). For about $2/chip and a failure rate (for me) of about 1 in 100.
-Adam On Sat, Mar 10, 2012 at 3:21 PM, Cobra007 <mic...@xiac.com> wrote: > > > > On the production Nixie Ramos clocks I intend to use these: > http://www.nxp.com/documents/data_sheet/PMBTA42DS.pdfThey are dual > > NPN 300v transistors that are really cheap. The downside is that there > > are only 2 transistors per chip, so that's 5 per digit, so they are > > going to significantly increase your part count on your board. But > > they seem ultra-reliable, and at the cost I think they justify the > > added part count. > > > > -Paul > > > > > I had been looking at those PMBTA42DS dual NPN transistors for my > nixie watch but found that the layout of the 2 transistors is not very > convenient to cramp them onto a very small PCB. I prefer to have both > collectors at one side of the chip and both bases at the other side. > This is the case with the DMMT5551S. Only downside is that they are > 180V models, so they are probably barely sufficient for your clock. I > know there's been a lot going around that 50V would be enough etc etc, > but if you really want the maximum performance of your clock/watch > including PWM, blanking etc etc it is still better to go for high > voltage drivers. I ended up using the BSS131 mosfets which are nearly > impossible to cramp onto a tiny board, but they still fit and it also > saved me a base resistor. > > Michel > > -- > You received this message because you are subscribed to the Google Groups > "neonixie-l" group. > To post to this group, send an email to neonixie-l@googlegroups.com. > To unsubscribe from this group, send email to > neonixie-l+unsubscr...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/neonixie-l?hl=en-GB. > > -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
