Hi all,
For what I can expect, a diode is series should apply nothing than a positive 25Hz (or 30Hz) half wave accross light bulb. The positive half wave amplitude should be 320 Vp (or 160 Vp). So, I'm expecting a reduced light with some flickering effects (due to poor retina effects persistence at frequecies less than 50Hz).
About the "Free energy" effects... I don't know. The only reason the meter cannot see energy is when the "cos pi" or phase angle is much less of 1. In fact meter counts just the real power and When cos pi goes to 0, that is a big reactive load exist over unbalance line (for instance, like motors with wrong phasing capacitors), the meter cannot counts a real power flow. This is a condition to strongly avoid and in most of country is illegal.
In this case, however I couldn't understande why the meter got confuse, as diode and light bulb are resistive loads, so (assuming low the line inductance) no phase angle exist. The reducing power is just due to reduced voltage accross the bulb.
To make longers the life of bulbs they are other methods. As Phasor has said the only reason the bulb blows is when switched on the peak of voltage (where the power in max). Electronic switches with zero crossing trigger, generally guarantee a long life to our light bulbs.
james