A number of readers contacted us by phone and email to ask about the "Enersonic Power Saver". This was featured on the Seven Network’s "Sunrise" program on March 3^rd and is the subject of favourable comment on a number of websites, such as www.gadgetguy.com.au

Those who had seen the Electricity saving box article were curious/concerned/outraged that a similar device would appear so soon after the first had been thoroughly debunked.

Fig.1: the circuit of the Enersonic Power Saver. If you have a sense of deja vu, it just might be because this circuit is virtually identical to that of the "Electricity saving box", which we thoroughly debunked back in our November 2007 issue. We thought such scams had been laid to rest...

We promised to follow it up and checked the Harvey Norman website to find out about the device.

I then went to our nearest store and while the helpful salesman knew about it, they did not yet have stock available. As I left, he remarked that it "worked by cutting the amperage, not voltage". "Hmm, that’s interesting", I thought.

The poor sod had no idea...

On the way back to the SILICON CHIP offices, I remembered that an American company devised a power reduction circuit for induction motors during the 1970s. This used a phase-controlled Triac to slightly reduce the voltage to the motor which apparently had the effect of reducing power consumption while not making much of a difference to reliable running of the motor.

In such a device, you cannot reduce the voltage by very much, say no more than 15 or 20%, otherwise the induction motor would refuse to start and be at risk of burnout.

In practice, I think the device did not catch on and its power savings would have been marginal anyway.

So I wondered whether this new Power Saver could possibly be based on a phase-controlled Triac.