IN-14 strike at 170V, but when multiplexed this should be a bit higher. That's why it's set to 200 volts. It then drops to 140V according to the datasheet, but in reality, I measured 144. So if I take 200-140 it's 60 volts across the anode resistor, giving the peak of 8mA. But to be honest, I am really confused with this. By my calculations, with 26.7% duty cycle per tube, for current of 2mA, I should have a peak of 3.864mA ( 2/sqrt(0.267) = 3.864). So with my supply stable at 200V and anode resistors of 7.5K, I should get the 8mA peak on one tube, or 16mA on two tubes, but I really measure current of 6.4mA alltogether that goes from my supply. How is this possible? Why should my supply give me 48mA when I need only 6.5mA for two tubes at a time? By the way, I am using blanking period of 200us, so maybe the current really settles by this time, so the supply needs to give enough current for only 2 tubes. Can someone clear this out to me?
And about that spider web.. it isn't really as messy as it looks in the video. It's just a matter of viewing angle. And everything is organised by cable color. Thanks On Mar 14, 1:24 am, Cobra007 <mic...@xiac.com> wrote: > Wow, I like that spider web you created there! > > How exactly did you estimate that a 7.5k resistor would result in a > 8mA tube current? Honestly, I do not know the nominal voltage of the > tube but I don't think it will be less than 150V. In that case, you > have a maximum of 50V across your resistor which would only be 6.7mA. > If you measure 5.5mA, the voltage across the resistor would be 41.25V > so in that case, your resistor should have been between 4.7k and 5.2k > to come to 8mA. My best guess is 4.7k. Try one tube and see if the > value is then closer to 8mA for that tube. Also check that your 200V > stays stable and can supply the required 48mA. > > Michel > > On Mar 14, 10:56 am, Imbanon <imba.a...@gmail.com> wrote: > > > > > > > > > Got my hands on some older Tektronix oscilloscope and a Fluke 199c. I > > did quite a lot of measurements, even with the current probe. I > > learned a lot about the tubes and their behaviour, but didn't really > > solve my problem. > > I ended up calculating my anode resistors (around 7.5k), that should > > give a peak of 8mA, but gives 5.5mA measured with a scope. You can see > > the result in the video below. The quality isn't at it's finest, but > > it's better than nothing! > > Check it out and tell me what you think. > > Also, the supply is set to 200V. It that too > > much?http://youtu.be/p7QNEL8s4l4 > > > Thanks everyone > > > On Mar 6, 10:10 pm, "Frank Bemelman" <bemel...@franktechniek.nl> > > wrote: > > > > AC DMM’s always excluded the DC component, if I am not mistaken. For a > > > mainly > > > troubleshooting tool (citation needed), that is not a bad choice. After > > > all, > > > many AC signals > > > found in circuits have a DC offset. Assuming sinewaves makes the design of > > > the meter > > > easier (cheaper). > > > > I would not expect a different behaviour from a DMM that is TRUE RMS. Nice > > > to have > > > that AC/DC switch though, on the Tek meters. But I’m still a Fluke only > > > guy > > > ;-) > > > > Frank > > > > From: Nick > > > Sent: Tuesday, March 06, 2012 4:03 PM > > > To: neonixie-l@googlegroups.com > > > Subject: [neonixie-l] Re: Calculating multiplexed nixie's RMS current > > > > Yes, RMS has only one physical definition, but in the case of DMMs the > > > actual implementation is obfuscated. > > > > "true" RMS in a DMM context is an RMS calculation that does not assume a > > > sine wave - most cheaper DMMs do indeed assume a sine wave input. > > > > Then there are "true RMS" (and indeed "ordinary" RMS) DMMs that may or may > > > not include any DC component, or at least in the Tek case, give you the > > > choice. > > > > Old meters indeed did use to measure the heat produced in a resistor - the > > > definition of the "RMS value" used was that of the DC voltage that would > > > give the equivalent heating effect to the signal under inspection. > > > > Nick > > > > On Tuesday, March 6, 2012 2:16:45 PM UTC, GastonP wrote: Actually there is > > > > only a definition of RMS, not subject to > > > "trueness" :) > > > >http://en.wikipedia.org/wiki/Root_mean_square > > > > AFAIK, the old instruments that gave a true-"true RMS" output measured > > > the heat generated by the signal when applied to a resistor. That way > > > the waveform shape did not affect the measurement, and they were able > > > to measure with the DC component included, something fake-"True RMS" > > > instruments can't do. > > > Many of the existing instruments assume sinusoidal signals and thus > > > are subject to gross errors. > > > > Gaston > > > > On Mar 5, 6:15 am, Nick <n...@desmith.net> wrote:> On Monday, March 5, > > > 2012 8:46:42 AM UTC, Cobra007 wrote: > > > > > > Yes, you're right Nick, the Fluke is indeed AC coupled. I didn't > > > > > expect that to be honest as it undermines the definition of "true RMS" > > > > > but a simple battery test shows 0V RMS :-). > > > > > Its not a commonly known problem, even among professional EEs. One of my > > > > DMMs, a Tektronix DMM916, has the option to include/exclude any DC > > > > component as required. I've had "forthright" discussions with some over > > > > what theoretically constitutes true-RMS vs. what they expect/want in > > > > actuality. > > > > > Nick > > > > -- > > > You received this message because you are subscribed to the Google Groups > > > "neonixie-l" group. > > > To view this discussion on the web, > > > visithttps://groups.google.com/d/msg/neonixie-l/-/cOKZXWW5GXwJ. > > > To post to this group, send an email to neonixie-l@googlegroups.com. > > > To unsubscribe from this group, send email to > > > neonixie-l+unsubscr...@googlegroups.com. > > > For more options, visit this group > > > athttp://groups.google.com/group/neonixie-l?hl=en-GB. -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. 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