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" <[email protected]> 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: [email protected] > 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 <[email protected]> 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 [email protected]. > To unsubscribe from this group, send email to > [email protected]. > 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 [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.
