Hey, I just tested M.J.'s anode driver, with no luck. Performance is the same. Also, the reason I don't need a resistor between MPSA92 and MPSA42 is because (according to Jason Harper) the resistor between MPSA42 emitter and ground forms a constant-current driver. Check out http://nixietube.info/NixieTransistors.pdf, and go to the bottom of page seven. I am using a 10k emitter-ground resistor. Per the advice of this board, I replaced the 1 megohm resistor with a 10k resistor and per my own advice I put another 10k resistor between the MPSA42 and microcontroller.
Also, I don't think an anode delay is the problem because if I disconnect the anode controller of one nixie, the other one shows no ghosting. If the anode was really staying on too long, there should be some ghosting in this situation, right? But if you think it would help I'll go ahead and take a picture later. Will On Feb 6, 12:09 pm, David Forbes <[email protected]> wrote: > On 2/4/11 11:09 PM, will wrote: > > > I got my IN-14s in the mail the other day (Well, three out of four, > > one was broken, but m_bulb on ebay very kindly offered to send me two > > more tubes. Awesome customer service right there). I've been working > > on multiplexing them, and everything works well except for the fact > > that I'm experiencing some annoying ghosting. My code basically looks > > like this: > > Any idea why my tubes would be doing this/ideas to fix it? Thanks! > > Will, > > I took a look at your schematic diagram. The anode driver has a problem. > > There should be a high value resistor (220K ohm) between the collector > of the MPSA42 and the base of the MPSA92. This limits the current > flowing through that 180V drop. > > The lack of those resistors may be causing way too much current to flow > from the base-emitter junction of the MPSA92, causing it to have a long > storage time. > > Also, you don't need resistors between the MPSA42 emitter and ground. > > Please post a photograph or two of your actual circuit as you built it. > Many times a problem becomes obvious when looked at by other eyes. > > For what it's worth, I used the circuit shown here in my multiplexed > clocks, and they didn't have any ghosting problems. > > http://www.cathodecorner.com/nc620akitman.pdf > > I also built them on PC boards, so the capacitance of the cathode > connections was lower than it is for a hand-wired circuit. That's why it > would be good to see your actual construction - there may be things > going on that you aren't aware of, not having 35 years of experience > making mistakes in electronics construction as I have. > > -- > David Forbes, Tucson AZhttp://www.cathodecorner.com/ -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To post to this group, send an email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
