Hi John & PIClist:
bulb detection...
-----------------

By using an impedance measurement looking toward the lamp and the rest of the 
house isolated with chokes good at the test frequency.  Instead of using a 
random frequency for the measurement, choose a frequency that will detect not 
only incandescent bulbs but also CF and LED bulbs in either the on or off 
state.  A similar technique is used for testing batteries.


Hi Carl:
House load monitoring
---------------------

Some years ago I connected a current transformer on one of the branch circuits 
  by removing the wire from the breaker and threading it though the hole in the 
current transformer.  Do not use a clamp on type transformer, they have a much 
lower dynamic range because of the residual air gap when closed and so can not 
see the small loads.

The current on one breaker is 20 amp max so that's the size of current 
transformer needed.  Since you know what loads are on each breaker you can 
choose which ones you want to watch and only put transformers on them.

I soldered a resistor across the output winding then ran wire to a Radio Shack 
Color computer that had an AC voltmeter input card.  On the screen there was a 
plot, similar to what's used with seismometers, so instead of only having one 
screen width you can have say 24 screen widths all displayed at once.

After a day when you look at the screen it's amazing what you can see.  For 
example the first thing you notice is the refrigerator which is a constantly 
cycling load.  If someone gets up during the night and opens the refrigerator 
door you see the light come one, or if they turn on a room light you will see 
that.  In the morning or evening where there's a lot of things being turned on 
and off in parallel it's hard to separate then, unless they have a unique 
current, then when you see a step of that size you know what it is.

If I was going to do this now using one of the Onset Computer U12 data loggers 
(most if not all PIC based and very cleaver) would be the way to go.
http://www.pacificsites.com/~brooke/Hobo.html  <- 16C56, TLC549, 8 bit A/D, 4 
ea. 24LC65, 2032 coin cell (old)
http://www.pacificsites.com/~brooke/GPend.shtml <- 16F690, 24LC512, single LED 
2-way interface, 2032 coin cell, XL330 3-axis accelerometer

Have Fun,

Brooke Clarke


-- 
w/Java http://www.PRC68.com
w/o Java http://www.pacificsites.com/~brooke/PRC68COM.shtml
http://www.precisionclock.com
-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist