> However, you can only use the average values if either the tube > voltage or tube current is constant; in my case this is not so. So I > would say I need to use the RMS values of tube voltage and tube > current. If I measure these with a scope, I come to 113V RMS and > 3.73mA RMS. This would then result in a 96% efficiency!!! > > This measuring must be correct, right?
The measuring is probably correct (subject to the definition of RMS when largish crest factors are involved). However, the math is invalid. To compute the correct power draw with AC waveforms, you have to multiply the instantaneous voltage by the instantaneous current moment by moment, and sum up all the products over at least one full cycle. Even with plain old sine waves, just multiplying RMS voltage by RMS current can be misleading, due to phase differences. That's the real difference between VA and watts. - 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 https://groups.google.com/groups/opt_out.
