Hi Michel, This is a fare point, 0 - 99 would be allot nicer, I wonder if I should just bite the bullet and use an IO port expander IC on the nixie display PCB I dont think I have enough room spare on the PCB to implement the latches unless I can do it with one IC (do you have any that come to mind?). This would solve all my problems in one go if I can find/make the space for it. I will have a look to see if I can squeeze a SM package onto the PCB in the remaining limited space.
I do like the IN-13 but am sadly too far into the design to make use of one. I do however have a second project on the go which is an audio spectrum analyser using IN-9 's :o) I just wish I had more spare time on my hands to spend more time on my many projects. Regards, Tim On Friday, 4 January 2013 22:48:50 UTC, Michel wrote: > > Hi Tim, > > Not that I want to influence your design but it sounds a bit odd to have > the nixies go from 0 to 63 in a valve (pre)amplifier. It is really related > to something digital that IMHO doesn't really match a design of a valve > amplifier. I think it is nicer if it would go from 0 to 99. If you use a > few latches before the 74141 that would solve all your limited I/O > problems. Another thing that comes to mind is using an IN-13 bar graph tube > to indicate the position of the volume button. > > Michel > > > > > > on Jan 05, 2013, *Tim* <[email protected] <javascript:>> wrote: > > Hi, > > Thank you for your reply David. My reason for multiplexing was due to not > having enough spare pins on the PIC, however having givin this considerable > thought I have the IO pins that were being used to switch the MSD and LSD > anode transistors and a third IO pin which was available to control the > enable pin for the tayloredge SMPS, so by using these three pins allows me > to to have 0 - 7 on the MSD which is great as I wanted 64 steps to > indicate the volume control potentiometer position. > > Sadly there is a but to this (is there not always) I need to be able to > blank the digits which normally involves using all 4 bits of the 74141. > Now as I do not need 7 - 9 I was thinking I could shift all the digits > along one position, so 0 in the nixie is connected to 1 on the 74141 1 to 2 > and so on. This results in being able to blank the nixie by sending 000 to > ABC and having D permanently tied to ground. This digit shift being easy > to work around in the firmware. > > I can position the SMPS in such a way that it will not interfere with the > audio signal path so I would like to try and stick with it for the nixie HT > supply as the valve HT supply has a delayed start to give chance for the > soft started heaters to warm up. I want the volume indication to come on at > power up with a possible count down on it to show the remaining warm up > time. Additionally to this I am trying to keep the analogue and digital > power rails separate from one another. > > This is where my questions begin: Can I leave the cathodes 7 - 9 > floating or do they need to be tied to something? Will floating digits > ghost? I would also like to > keep my enable signal to disable the SMPS when the amplifier is in standby > so can I use the now unused 0 output on the 74141 as a logic > signal to drive the enable pin on the SMPS? The only trouble with this is > when blanking the nixie the SMPS will be disabled unless I use extra logic > to look at the LSD bits? (I guess it is quite environmentally friendly to > turn the SMPS off when the digits are blank but if I was worried about this > then I guess I would not be building a power hungry inefficient valve > amplifier!) > > Regards, > Tim > > > > On Wednesday, 2 January 2013 22:25:13 UTC, nixiebunny wrote: >> >> On 1/2/13 3:01 PM, Tim wrote: >> >> > I am in the process of building an audio preamp using valves and I am >> >> > using nixie tubes to indicate the volume control position. I am using >> >> > two nixie tubes to indicate the volume and they are being multiplexed >> >> > via a PIC and 74141. >> >> > >> >> > My question to you fine folk is how should I provide power to the nixie >> >> > tubes. I have two options available to me: >> >> > >> >> > >> >> > Regards, >> >> > Tim >> >> >> >> Tim, >> >> >> >> If you can afford the extra four pins on the PIC and another 74141, then >> >> you can run the tubes direct (non-multiplexed) and not worry about it. >> >> >> >> If you will be multiplexing them, then the power supply will not conduct >> >> the noise to any noticeable extent. You will need a high anode resistor >> >> value, so you can insert a simple two-stage RC low-pass filter (10K >> >> series, 0.1uf polyester shunt) between the power supply and the anode >> >> resistors to eliminate noise from the anode power. >> >> >> >> You will want to be careful about mounting the display unit away from >> >> the input stage of the amplifier, to prevent radiated noise from getting >> >> into the input stage where it will be amplified. >> >> >> >> -- >> >> David Forbes, Tucson AZ >> >> >> >> > > > > -- > > 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]<javascript:> > . > > To unsubscribe from this group, send email to > [email protected] <javascript:>. > > To view this discussion on the web, visit > https://groups.google.com/d/msg/neonixie-l/-/wzW1euMoJw0J. > > For more options, visit https://groups.google.com/groups/opt_out. > > > > > > -- 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]. To view this discussion on the web, visit https://groups.google.com/d/msg/neonixie-l/-/reDXte0aTDkJ. For more options, visit https://groups.google.com/groups/opt_out.
