Hi gregebert! Thank you so much for your reply. I've taken a look at the datasheet for the HV5530 and it seems like it's a no brainer to use this instead of the transistors to simplify things so I will be taking some time to modify that. However, I do have a few follow up questions about some things you said that don't quite make sense to me that I'd like to understand for my own future benefit. What do you mean when you say the NPN transistors will only drive out 4.3V? The transistor I was planning on using was the MPSA42 which is a high voltage-power transistor. The datasheet says that Vce is about 0.5V, so disregarding the anode resistor, if I were to drive the Nixies with 170V supply, shouldn't the anode see about 165.5V. Also, using an NPN I thought that the 74HC238 would be sourcing the current rather than sinking it. Am I incorrect in this thinking? Thanks again for your reply and helping me to understand this stuff.
Shep On Tuesday, March 29, 2016 at 1:04:19 PM UTC-6, Asstroman wrote: > > Hello, this is my first post here in the NeoNixie group so I hope this is > an acceptable thread topic. I'm excited to find other people interested in > this sort of thing to get some feedback if anyone has it to offer. > Attached is a preliminary schematic that I designed for my first go at a > Nixie clock. (When I say I designed I mean pieced together from the > internet and filled in some gaps). I'd greatly appreciate any feedback > anyone has on it concerning better methods or any major problems that would > prevent if from working. Eventually I'd like to add in more features like > acquiring the time via WiFi or GPS, temperature sensing and better dimming > control and such, but for now I'm keeping it relatively bare bones (I > think). I'm using an Atmega328p as the uC which will be communicating via > I2C with a MAX1771ESA+ RTC chip. Even though I know multiplexing shortens > the lifespan of the tubes I've decided to go with using MUXing because I'm > not so knowledgeable on SMPSupplies (yet) and don't quite know how to get > the necessary current out of one to use Direct Drive. My scheme is to use a > 3:8 encoder on the anode side to select which anode is on. And on the > cathode side I'm using a bin-decimal converter to select which digit is > displayed. Each digit of a tube is attached to the same digit on the other > tubes so that when the bin-decimal converter turns on the base, say for the > "1"s transistor, all the "1"s for each tube will turn on on the cathode > side, but only the correct anode will be on, thus displaying only the > correct number on the intended tube. I haven't seen another design that > does exactly this in the same way so I am not 100% confident it will work. > It seems pretty straight forward, but then again, as with all electronics > projects it probably isn't. I will include in my code some measures to > avoid cathode poisoning, however, I just learned of another issue which is > blue spots appearing somewhere on the anode mesh... I think. I still need > to do some research about this and how to avoid it but if anyone has any > knowledge about this they'd like to share I would appreciate it as I'd like > to avoid this from happening in my design. Thanks for your time and I look > forward to any and all responses. > > > Shep > > > > <https://lh3.googleusercontent.com/-RRq4J135lbY/VvrQxlYW6XI/AAAAAAAAAIc/2oLMtnUf_D8VJ-XBmZ1EXu7h3Dj5EsVsQ/s1600/PG1.png> > > > > > <https://lh3.googleusercontent.com/-X4PchxD2EL0/VvrQiT0novI/AAAAAAAAAIU/cnEds-f5Ogw4bWnU0JzZSScAFpwxayLbw/s1600/PG2.png> > > > -- 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 post to this group, send an email to neonixie-l@googlegroups.com. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/7135516d-3b7d-490b-a3aa-2b95df230a2b%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
