It all has to do with how you design the circuit around the Nixie, in the old days the transistors did not have perhaps more than 120V Vce as a maximum, usually lower than that, around 80-100V. With a lower Vce you have to use either a cathode bias voltage to meet the transistor requirements or youll have to use both a positive and negative voltage to get the bias which the transistor would work with. Then if you lower the resistor or raise the voltage is up to what you want to achieve and what transistors you have at hand. It also has to do with what turn-on time (ionization and de-ionization) that you want to acheive. Some of the Nixies datasheets for multiplexing specify a 100uS pulse as the shortest ionization pulse width in these datasheets and roughly 200-400uS for de-ionization pulse width this was also due to how the transistors were able to switch these voltages and not only due to the Nixies. Modern transistors are able to switch these currents and voltages faster than the older types so you could possibly have shorter pulses which acheives the same effect. The most common way of looking at the pulses and currents/voltages involved, by these books and datasheets, is by using the average voltage/current and not the RMS values since the pulses are square pulses and not sinusoidal waves or triangular waves. Here's a nice sheet showing RMS, Mean and their relationships: http://www.yokogawa.com/gmi/pdf/Bulletin/Bull-DMMglossary-E.pdf .
There are quite a few examples in the book I mentioned above on how the Nixies were designed to be driven in those days. This is not the only book showing how this is suppsed to be done, but all that I have found have been written in German, there are possibly some english books to which show these details, probably from Philips or Valvo as they published a lot of design examples. I have been quite happy with the German books as they are easier to find and I guess were also printed in larger quantities and not so collectable as the English ones, which I guess is the reason why they are harder to find. /Martin On 16 mar, 09:54, Cobra007 <[email protected]> wrote: > That makes sense indeed. > > What would the reason be to choose for a higher voltage rather than a > lower anode resistor? You can achieve a higher tube current by either > raising the voltage or lowering the resistor, so what is the advantage > of raising the voltage? Is it because ionization will be quicker or > doesn't have that anything to do with it? > > Michel > > On Mar 16, 7:13 pm, Dekatron42 <[email protected]> wrote: > > > > > Many manufacturers write that you will have to contact them for the > > special curves you need when you are going to multiplex their Nixies > > since they do not usually print that information in the databooks. > > > These sheets show you that the Nixie will have an increased turn-on > > voltage corresponding to the increased current when run in switched > > mode. This is the same as when a neon voltage stabilizer tube is used, > > the voltage increases somewhat when the current increases, you can > > check the OB2 voltage regulator tube for instance. > > > The curves for most Nixies when used in multiplexed mode are not > > linear so if you can't find those curves you'll have to make the > > measurements yourself and take into account the spread between > > different Nixies to draw the curve. Some of these special curves have > > a voltage span of approximately 10-30V for a certain current through > > the Nixie, so there is an upper and a lower limit for the turn-on > > voltage corresponding to the current used. > > > This book:http://www.oldtimeradio.de/BU7908.php"Electronica 171 - > > Elektronische Anzeigebauelemente" by Winfired Müller contains a few of > > these curves for the ZM-series of Nixies. > > > /Martin > > > On 16 mar, 00:55, Cobra007 <[email protected]> wrote: > > > > Yes, I think I mentioned "slightly" increase rather than a mayor > > > increase. > > > > I have measure this on another nixie tube and came to the following > > > voltages: > > > 0.5mA : 120V > > > 1.0mA : 125V > > > 1.5mA: 130V > > > 2.0mA: 133V > > > 3.0mA: 140V > > > 4.5mA: 150V > > > > His tube current will increase from 2mA to about 7.5mA, so according > > > to the above measurements, the increase in tube voltage will be > > > playing a role. > > > > Michel > > > > On Mar 16, 10:06 am, Charles MacDonald <[email protected]> wrote: > > > > > On 12-03-15 05:46 AM, Cobra007 wrote: > > > > > > So it looks like your resistor is correct. The only thing is that the > > > > > voltage across the tube will slightly increase due to the higher > > > > > current, so it's not 100% correct but pretty much. > > > > > Since we are talking a Neon device, the voltage across the tube will try > > > > to stay the same, with the current adjusting if needed. That is why > > > > Neon bulbs were used as Voltage reference devices in days of Old. > > > > > -- > > > > Charles MacDonald Stittsville Ontario > > > > [email protected] Just Beyond the > > > > Fringehttp://users.trytel.com/~cmacd/tubes.html > > > > No Microsoft Products were used in sending this e-mail. -- 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.
