Over that voltage range, I would expect three branches on the IV. Did you also track the firing voltages and extinction currents? Dark rooms vs well-lit? Ambient temperature?
On Friday, May 15, 2020 at 8:57:08 AM UTC-7, gregebert wrote: > > Yes; for a given segment, there are tube-to-tube variations in segment > current for a given voltage. > The data below is for 8 tubes, for segment #1. > > At 200uA, the voltage varies from 127 to 138V. At 6mA, the voltage varies > from 169 to 181V > > Using just a resistor for setting the current will result in large > variations across tubes and supply-voltage. That's why I use > current-regulators on each cathode. It's probably overkill, but given the > ridiculous pricing for b7971's, I'm not taking any chances. I have no > spares for my 8-tube clock; just 2 tubes that have a shorted or dead > segment. > > I have no idea what happens over time, but I suspect that as tubes age the > current, hence the brightness, decreases for a given voltage. In a few > years, I will retake the data and see what has happened. This clock went > into service in 2017. > > 0.2 0.5 1 2 3 4 5 5.5 6 <-- Current > 130 133 138 145 152 159 167 170 172 <--- Tube 1 > 135 138 143 151 158 166 174 178 181 > 134 137 142 150 158 166 174 178 180 > 138 138 140 145 151 158 164 169 172 > 137 138 142 148 156 163 172 176 180 > 135 136 140 147 154 162 171 174 177 > 131 134 138 144 151 158 166 170 173 > 127 130 134 141 147 155 162 166 169 <--- Tube 8 > > -- 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 [email protected]. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/3ac7a215-df3c-42e6-a37f-6c0d11e144ce%40googlegroups.com.
