hi there
can anyone tell me how can I build a circuit that would detect when a plasma TV is under load (wakes up) and then turn an light bulb/fluorescent tube 'on' via timer.

the idea is when there is change in power draw due to plasma TV going from "sleep" mode to power mode a current sensing circuit turns on electronics with a relay that then turns a light and holds it in "on" position for say 1/2 hour or so.

input voltage to plasma TV is 120V.
amperage that TV draws when it wakes up is probably in range of 5 A or more
and when in sleep is most likely in single digit watts.

thanks for any suggestions

 

You could use a current transformer on the plasma tv's power cord, use this and a comparator. When the current goes up the comparator output will be pulled up by a pull-up resistor and turn a relay on.

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Metal-Oxide-Semiconductor Flame Effect Transistor

 

thanks for you answer

what kind of current transformer can i use to accomplish this?

would something like this work:

AC Current Sensing Transducers

Current Sensing Transducers Overview