How green is my green electronics ? Now with improved threshold detection !

Step 3 How it works. The current monitor

The current required by the electronic devices under test is monitored through a current transformer.
I made it out of a regular wall adapter: I removed the low voltage secondary winding and replaced it with 4 turn of paired 1.5 square mm insulated wire. Current flowing through the new winding produces a voltage across the untouched original 110Vac side of the transformer. The higher the current, the higher the voltage.
The untouched 110Vac primary is then connected to a filter stage, a variable gain amplifier
a full-wave rectifier, a peak detector and a threshold detector feeding a transistor and a low
power relay. The contacts of the relay are in series with the voltage coil of the meter.
The gain of the amplifier stage is regulated through a potentiometer to set the threshold stand-by / operational.
You can find the detailed schematic down here.
All the parts are pretty common and most of them can be salvaged from other electronic devices.
Almost all the electronic components I took from a VCR and an automatic IR night light.