> 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?
Ionization will be quicker with a higher voltage. Mike M. (threeneurons) actually went to the trouble to measure the turn-on behaviour of a nixie: http://threeneurons.files.wordpress.com/2011/08/timing01.jpg I'm thinking of duplicating his setup and trying it with different anode voltages and a few different nixies (I'm guessing little nixies ionize faster). I may also try using a decimal point as a "primer" and even comparing nixies with and without ambient light. Another advantage of higher voltage is better current regulation - since more of the drop is across the anode resistor and less across the (dynamic, negative, varies with the digit lit) resistance of the nixie, the current for different digits will be more similar. A disadvantage of higher voltage is lower efficiency - more of your voltage is used up in the anode resistors as heat. This can be combated by using a current-limited supply, which can give wonderful efficiency but adds a good deal of complexity (current limiting a negative resistance load which is being continually switched ain't easy). Alternatively, a scheme like David uses in his watches (raising the voltage to strike, then lowering it) strikes a different balance between ionization time, efficiency, and complexity. Another disadvantage is the voltage impressed on the "off" cathodes if the anode voltage is turned on but the digit is blanked. This can lead to ghosting (especially if the transistors are zener clamped or leak at high voltage) or failure of the cathode switches if they can't withstand the voltage. An obvious way to address this is don't enable the anode switch for blanked digits, which requires a few wiring and/or software considerations, depending on the design. - John -- 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.
