# How does this power saver work?

#### praondevou

Joined Jul 9, 2011
2,935
Has anybody bought this "power saver" and tested it?

Logic is telling me, that it doesn't work.

"It uses a state of the art electrical technology to actively monitor and improve the power factor of electrical appliances ,suit for household or office. "

What do they mean with "improve"? Even if they change the power factor, wouldn't the active power drawn from the grid remain unchanged (with same load)?

http://www.ebay.com/itm/18KW-Power-Energy-Saver-Electricity-Save-up-35-Money-/110683037074?pt=LH_DefaultDomain_0&hash=item19c5391d92

#### iONic

Joined Nov 16, 2007
1,650

#### praondevou

Joined Jul 9, 2011
2,935
I'm sure that it's composed of a small non-polarized electrolytic capacitor, along with just enough parts to power the green LEDs.

There's a similar scam being sold that plugs into a vehicle cigarette lighter socket; it has a blinking blue LED to "tell you that it's working". Only $29.95. And there are people who actually buy this stuff... I once saw a device that could make you "hear" through nerve cells on your arm. (it was much more than$30)
While it's certainly possible to train your brain to a number of things (like the blind guy who was trained to see through electrodes in his visual centre) I found this device a bit strange. So I read about nerve pulse propagation speed and found out that it's too slow for audio frequencies to be passed through. I asked a biologist and he confirmed it. He said, add it to the pseudo-inventions people come up with once in a while.... SCAM.

Joined Jul 7, 2009
1,577
Only $29.95. You could used to get a car painted for that. Now you just get fleeced. Earl Schieb -- I got my 1963 Pontiac painted by them for$30 around 1968 -- and it wasn't too bad of a deal...

#### tom66

Joined May 9, 2009
2,591
The simple fact is that it doesn't save energy.

Two points:
- Residential customers ARE NOT BILLED for non unity power factor
- The mentioned device couldn't be a one-do-all appliance; power factor correction is a per-device custom engineered solution, usually consisting of a bank of capacitors and inductors

Inside the device?

source: Silicon Chip (http://www.siliconchip.com.au/cms/A_110502/article.html)

The above circuit is DANGEROUS and must not be built by novices as it is not isolated from the mains. The design consists of a few components to light the LED (the right hand side) and the "power factor correction" circuit, consisting of a tiny 6µF capacitor and a 330k resistor, in series with a fuse.

If anything, it will USE more energy than it could possibly save. For one, the 330k resistor will dissipate 0.16W @ 230VAC. The 220nF cap and LEDs might use 0.05W, or based on the typical efficiency of a capacitive power supply, possibly more. So right up front that thing is eating 1/5W or more and not saving anything...

Sure it will only cost 21 pence a year to operate where I live but compare that to the zero savings...

The ONLY neat thing about it is the 390V MOV might actually surpress some spikes on the line. Then again, it's probably too small to have any protective effect.

#### praondevou

Joined Jul 9, 2011
2,935
That's a shame. Not everybody is technically inclined...

That's why I usually research everything exhaustively before buying....

I couldn't protect myself from e.g. construction material scam, I guess..

#### kubeek

Joined Sep 20, 2005
5,587
"It uses a state of the art electrical technology to actively monitor and improve the power factor of electrical appliances ,suit for household or office. "
It can never monitor power factor as it knows nothing about the main current. Even if there was an inductor to correct for switching psu´s capacitors, it is a wild guess.

The other thing is that the meter measures real power and doesn´t give a damn about power factor.

#### praondevou

Joined Jul 9, 2011
2,935
Ok guys,

#### hspalm

Joined Feb 17, 2010
201
You have got to read this site
http://www.compendiumarcana.com/fuel_doctor_fd47/

It's a teardown and review of the Fuel Doctor fuel saver. It is basically reverse engineered schematics showing design flaws and errors, which if they were correctly designed would (of course) not help fuel efficiency anyways. On the bottom of the page you have a letter from the CEO of Fuel Doctor, remarkably intense and hostile way of writing, absolutely a fun read!

The author have been threatened with law suits which were never sent out.
http://www.eevblog.com/forum/index.php?topic=4023.msg53268#msg53268 oPossum @ eevblog forum

#### BrainFog

Joined Jan 24, 2011
122
I found this website a while ago where someone takes them apart to see how to build them. http://www.bigclive.com/power.htm

The bit "It gets a bit hot and smells all resistory when the plug has been "saving power" for a while." really made me laugh when I first read it.

By this sites standards they are dangerous as they connect LEDs directly to the mains. With such poor quality they could even be a fire hazard.

#### praondevou

Joined Jul 9, 2011
2,935
This is absolutely unbelievable. This doesn't seem to be a one man small scale scam. He even has an exhibition stand ??? How much courage does it take to do this? He probably makes lots of money with this BS. This guy should be put in jail.

Here is an example of how someone can get illuded by false publicity: http://www.benzworld.org/forums/w204-c-class/1511853-fuel-doctor-fd-47-a.html The guy actually considers buying one. Problem is not that people are stupid. There is too much technology on the market to keep track and to know everything...

Last edited:

Joined Apr 30, 2011
1,568
We often see posts from people claiming to be completing their various electrical engineering degrees and requesting ideas for a final project. I've always thought this was a clear indication that they'd chosen the wrong field of study for their temperament and I've never offered a suggestion, but now I have two: 1; design a universal appliance power factor controller that saves at least 10% over the baseline and 2; design a wearable battery powered mosquito repeller.

#### shortbus

Joined Sep 30, 2009
6,889
Could I save money instead of buying the, Fuel Doctor fuel saver, by putting a .01 capacitor across my battery terminals?

#### tom66

Joined May 9, 2009
2,591
Could I save money instead of buying the, Fuel Doctor fuel saver, by putting a .01 capacitor across my battery terminals?
Yes. But do not look into the operational end of the device.

#### chaithanyatkm

Joined Aug 26, 2011
23
wat really happend uncle..

#### JoeJester

Joined Apr 26, 2005
4,075
This increases MPG by making your wallet lighter.

This is nothing new ... The Electrical Engineer in 1888 did a bit on Keely.

PT Barnum reminds us there's a sucker born every minute.

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