[ARC5] Smart People: Multi-Set Current Corn-fusion

[David Stinson]

From: Mike Feher [mailto:n4fs at eozinc.com] 



When you have just one set on, did you include the
off current of the other sets. How were the
measurements made? 73 - Mike 

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Have them all on a common B+ buss, fed from a
regulated, current-limited supply.  Individually,
when off, the sets should draw about 4 mA each
(screen dividers).  Current is measure both at the
supply and via a Fluke bench meter in the Negative
lead.  Individual set current measurements do,
therefore, include the currents from the two "off"
sets, but that should amount to no more than 8 or
9 mA additional.  With all three sets playing at
identical levels, we seem to have 34 mA missing
here.

 

A dim bulb just went off in my head.

The DC current isn't constant; the current varies
with the receiver output, especially the Audio PA
output.  Bench meters "average" the current over
time.  Since the three receivers are outputting
different waveforms if plotted over time, the
average of the currents will not be a straight sum
of the individual currents, but rather an
*averaged* sum of all three over time.  i.e. At
any one instance in time, Set 1 may be at full
output and pulling 50 mills, while set 3 is silent
pulling 5 mills and set 3 is in between, pulling
20 mills.   Total at that time: 75 mills.  Take an
average over a long enough time and 83 mills is
probably right.  What do you think?  Somewhere
close?



73 Dave AB5S

 

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