[TCML] Optoisolated Power Meter -- Take II

[sparktron01@xxxxxxxxxxx]

Stephen Woodward has modified the original optocoupled
wattmeter to give you VA as well as W.  PF can be approximated
however, VA has no sign (leading [inductive +],
lagging [capacitive -] ).

I have built the first incarnation (original circuit) and with a 
741 could easily hit +/- 5% accuracy.  With a decent op-amp
OP-27, MAX427 better the 3% should be possible.
This circuit is designed for 120VAC, double 100K to (2) 100k
for 240V service or use current/potential transformers to 
improve hold off.

Hot off the presses in EDN 2/21 edition.

http://www.edn.com/contents/images/6531585.pdf

Regards
Dave Sharpe, TCBOR/HEAS
Chesterfield, VA. USA
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