Vampire Appliances

[Watson A.Name - "Watt Sun]

I was watching the local ABC News and they had a piece on vampire
appliances. They said that an appliance could be using about 5 watts
when it's turned off, and that's about $4.00 a month. This sounded a
bit high to me. But since I don't get an electric bill, I have no way
to tell.

5 watt-hours times 730 hours a month is 3650 watt-hours or 3.65 kWh.

More than a dollar a kWh?


--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@

 

[Richard Crowley]

"Ian Stirling" wrote ...

Some devices draw lots more power when "off".
My satellite reciever draws almost exactly the same
power when off and when on. Off is around 30W,
on around 32.

The way many modern microcontroller-run "appliances"
work, they need to maintain their processes between uses
(particularly external data-driven things like satellite receivers).

Many (most?) of these appliances are designed to have only a
"cosmetic" OFF function to satisfy more old-fashioned users
who grew up in the era of turning things off to save power.
Even VCRs from >15 years ago only blanked the front-panel
display in "off" mode. Some of them actually label the mode
"Standby" rather than "Off" which is more intelectually honest.

 

[Oppie]

The vampire thing was started a few years back by Power Integrations Corp
(afik) to push their high efficiency off-line switching supplies for standby
power.
http://www.powerint.com/slayingvampirespr.htm
http://www.powerint.com/nasdaqopeningpr.htm

Corny, Eh?
Oppie

"Watson A.Name - Watt Sun" <alondra101@hotmail.com> wrote in message
news:MPG.19eb0c30ca01a8a7989770@news.dslextreme.com...

I was watching the local ABC News and they had a piece on vampire
appliances. They said that an appliance could be using about 5 watts
when it's turned off, and that's about $4.00 a month. This sounded a
bit high to me. But since I don't get an electric bill, I have no way
to tell.

5 watt-hours times 730 hours a month is 3650 watt-hours or 3.65 kWh.

More than a dollar a kWh?

 

[Jerry G.]

All appliances that use a microcontroler for their operation require some
power to be maintained. The off switch on most devices today, only shuts of
the display, and some non required circuitry if that. In the case where
there are motors, heating elements, and other similar types of apparatus
used in the appliances, when in the off mode, these sections are disabled.

In the case of TV sets, the scan circuits, audio output stages, and the
front end tuner are disabled, because the horizontal and HV outputs sections
are disabled. The main processor is still running. Infact on all modern
equipment, where there is a remote control, or any type of auto function,
the microprocessor and its support circuitry must be running to be able to
respond.

There are also many devices where the power switch is purely cosmetic, and
the device is running all the time as normal. They only switch off the front
panel lights, and any displays to make it look like it is off.

I have a Scientific Atlanta digital box for my TV set. When it is turned
off, the time is showing like a clock. Internally, the unit is still working
fully, and the TV will even work on the same channel. It does however not
allow the channels to be changed when in the off mode, but the output is
operating fully. It is pulling about 30 Watts from the AC all the time. I
cannot unplug it from the AC, because I would have to get it re-initialized
by the service provider, and that can take about 15 to 20 minutes each time
I want to use the TV. Infact, the instruction manual indicates that the
unit can be left on all the time. There is no difference.

All your modern electric clocks that use an LED display will draw about 5 to
8 Watts on the average. Microwave ovens and TV sets will draw the same
amount when in the off mode. If you have an electric stove or any device
that has an electric clock and or a remote control to switch the power on
and off will also draw this amount. This also includes all models of
cordless phones.

In the province of Quebec, Canada, electric power costs an average of about
$0.04 US or $0.06 Cdn per kW/Hr. The typical home has about 10 devices that
draw about 6 Watts AC average when in the off mode. This is about 60 Watts
of power being used all the time. This is 0.06 kW each hour. This works to
about This works to about $0.06 US per day, or about $0.09 Cdn per day of
electricity. This is not very bad, considering the total cost per month of
operating a home.

The only other solution is to purchase all 1960's or earlier appliances and
devices for your home, if you can find them. You will be spending all your
time scrounging for parts and continuously fixing them. Infact, the old
1960's electric clocks with motors in them, required more current to operate
than today's modern LED and LCD clocks. The earlier appliances when
operating required much more wattage to get the same job done, therefore,
you will not win with this situation.



--

Greetings,

Jerry Greenberg GLG Technologies GLG
=========================================
WebPage http://www.zoom-one.com
Electronics http://www.zoom-one.com/electron.htm
Instruments http://www.zoom-one.com/glgtech.htm
=========================================


"Watson A.Name - Watt Sun" <alondra101@hotmail.com> wrote in message
news:MPG.19eb0c30ca01a8a7989770@news.dslextreme.com...
I was watching the local ABC News and they had a piece on vampire
appliances. They said that an appliance could be using about 5 watts
when it's turned off, and that's about $4.00 a month. This sounded a
bit high to me. But since I don't get an electric bill, I have no way
to tell.

5 watt-hours times 730 hours a month is 3650 watt-hours or 3.65 kWh.

More than a dollar a kWh?


--
@@F@r@o@m@@O@r@a@n@g@e@@C@o@u@n@t@y@,@@C@a@l@,@@w@h@e@r@e@@
###Got a Question about ELECTRONICS? Check HERE First:###
http://users.pandora.be/educypedia/electronics/databank.htm
My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
@@t@h@e@@a@f@f@l@u@e@n@t@@m@e@e@t@@t@h@e@@E@f@f@l@u@e@n@t@@

 

[Ian Stirling]

In sci.electronics.misc Watson A.Name - "Watt Sun" <alondra101@hotmail.com> wrote:

I was watching the local ABC News and they had a piece on vampire
appliances. They said that an appliance could be using about 5 watts
when it's turned off, and that's about $4.00 a month. This sounded a
bit high to me. But since I don't get an electric bill, I have no way
to tell.

5 watt-hours times 730 hours a month is 3650 watt-hours or 3.65 kWh.

More than a dollar a kWh?

Maybe they are talking about all the 5W loads.
20 5W loads does not sound utterly unreasonable.

Some devices draw lots more power when "off".
My satellite reciever draws almost exactly the same power when off and
when on. Off is around 30W, on around 32.

--
http://inquisitor.i.am/ | mailto:inquisitor@i.am | Ian Stirling.
---------------------------+-------------------------+--------------------------
My inner child can beat up your inner child. - Alex Greenbank

 

[Gary Tait]

Whereas On Mon, 6 Oct 2003 06:58:23 -0700, "Richard Crowley"
<rcrowley7@xprt.net> scribbled:
, I thus relpy:

"Ian Stirling" wrote ...
Some devices draw lots more power when "off".
My satellite reciever draws almost exactly the same
power when off and when on. Off is around 30W,
on around 32.

The way many modern microcontroller-run "appliances"
work, they need to maintain their processes between uses
(particularly external data-driven things like satellite receivers).

Many (most?) of these appliances are designed to have only a
"cosmetic" OFF function to satisfy more old-fashioned users
who grew up in the era of turning things off to save power.
Even VCRs from >15 years ago only blanked the front-panel
display in "off" mode. Some of them actually label the mode
"Standby" rather than "Off" which is more intelectually honest.

Actually, that chip/circuite (the display), stayed on. I'd have to
check some of my vintage machines, but you'd thing they'd shut off the
syscon, and analong circuits.
--
Gary J. Tait . Email is at yahoo.com ; ID:classicsat

 

[Lizard Blizzard]

Ian Stirling wrote:

In sci.electronics.misc Watson A.Name - "Watt Sun" <alondra101@hotmail.com> wrote:

I was watching the local ABC News and they had a piece on vampire
appliances. They said that an appliance could be using about 5 watts
when it's turned off, and that's about $4.00 a month. This sounded a
bit high to me. But since I don't get an electric bill, I have no way
to tell.

5 watt-hours times 730 hours a month is 3650 watt-hours or 3.65 kWh.

More than a dollar a kWh?


Maybe they are talking about all the 5W loads.
20 5W loads does not sound utterly unreasonable.

Some devices draw lots more power when "off".
My satellite reciever draws almost exactly the same power when off and
when on. Off is around 30W, on around 32.

It's the third article here: (for today, Oct 6, but who knows later..)
http://abclocal.go.com/kabc/features/consumer/

They mention that sat rcvrs draw almost as much power. What did you use
to measure the power with? A DMM on the AC current range? Then
multiply by the line voltage? I sure miss my Amprobe, which got stolen.
Really handy, however it required that the hot lead of the line cord
be separated from the others.


--
----------------(from OED Mini-Dictionary)-----------------
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(ii) there is no such word as ~her's, our's, their's, your's~.

Confusions: it's = it is or it has (not 'belonging to it'); correct
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----------------(For the Apostrophe challenged)----------------
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<<Spammers use Weapons of Mass Distraction!>>

I bought some batteries, but they weren't included,
so I had to buy them again.
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FOR SALE: Nice parachute: never opened - used once.

(Problem) Evidence of leak on right main landing gear
(Solution) Evidence removed

F
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f
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t
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"
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m
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..

 

[Lizard Blizzard]

Jerry G. wrote:

[snip]

Infact, the old
1960's electric clocks with motors in them, required more current to operate
than today's modern LED and LCD clocks.

The quartz sweep second hand clocks run for a year off a single AA cell.
So no power at all needed from the wall outlet.

The earlier appliances when
operating required much more wattage to get the same job done, therefore,
you will not win with this situation.

One of the ladies at work replaced her old fridge with a new energy
efficient one. Her electric bill went down fifty dollars a month(!)


--
----------------(from OED Mini-Dictionary)-----------------
PUNCTUATION - Apostrophe
Incorrect uses: (i) the apostrophe must not be used with a plural
where there is no possessive sense, as in ~tea's are served here~;
(ii) there is no such word as ~her's, our's, their's, your's~.

Confusions: it's = it is or it has (not 'belonging to it'); correct
uses are ~it's here~ (= it is here); ~it's gone~ (= it has gone);
but ~the dog wagged its tail~ (no apostrophe).
----------------(For the Apostrophe challenged)----------------
From a fully deputized officer of the Apostrophe Police!

<<Spammers use Weapons of Mass Distraction!>>

I bought some batteries, but they weren't included,
so I had to buy them again.
-- Steven Wright

FOR SALE: Nice parachute: never opened - used once.

(Problem) Evidence of leak on right main landing gear
(Solution) Evidence removed

F
o
d
d
e
r

f
o
r

s
t
u
p
i
d
"
n
o
t

e
n
o
u
g
h

i
n
c
l
d
u
d
e
d

t
e
x
t
"
e
r
r
o
r

m
s
g
..

 

[oldsoundguy]

On Mon, 06 Oct 2003 13:02:09 -0700, Lizard Blizzard <NOSPAM@rsccd.org>
wrote:

Jerry G. wrote:

[snip]

Infact, the old
1960's electric clocks with motors in them, required more current to operate
than today's modern LED and LCD clocks.

The quartz sweep second hand clocks run for a year off a single AA cell.
So no power at all needed from the wall outlet.

The earlier appliances when
operating required much more wattage to get the same job done, therefore,
you will not win with this situation.

One of the ladies at work replaced her old fridge with a new energy
efficient one. Her electric bill went down fifty dollars a month(!)

Old refrigerators and freezers wasted most of their energy in
generating heat, which if in a confined room, would lower the
efficiency of the unit itself, yet alone run the ambient temp of the
room up to an un livable level, requiring the need for an air
conditioner of some sort.
I have a full blown media room .. full stereo system (where the main
amp/pre amp is ON but display is off all the time .. phono pre amp for
my Linear .. Dolby 5.1 amp set up (on all the time) 32'HDTV .. screen
is the only thing that turns off, so it generates heat .. two
computers (P iv's) that generate a gang of heat (did go to an LCD
display which cut down on the heat from a monitor. .. but all along
the back wall behind a vented folding door set is a pantry, which
includes a huge side by side ref/freezer. so I have to have an 8000
btu air conditioner running 9 months out of the year. plus a Honeywell
Air cleaner to keep from having to open and CLEAN everything every
month!

 

[Robert Monsen]

I have a manutech current sense transformer I picked up from a junk box buy,
and I've been trying to build a simple kill-a-watt meter. Here is my
schematic:

3 to 2000
| |
| | -----+----------------
+----| | | | | ^
| C|| | C| .-. |
AC C|| | C| | | 100 ohms V Sense
| C|| | C| | | |
+----| | | | '-' |
| | | | v
| | ------+----------------
created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de

Now, this seems to approximately work for the three devices I've tried it
on:

100W light bulb, Vsense = 0.120V, computed power = 94W
25W light bulb, Vsense = 0.028V, computed power = 22W
AC Motor , Vsense = 0.220V, computed power = 167W

However, the question arises whether this will work for appliances.

1) I have a simple A/C meter. Does that do a passable job in this
circumstance?

2) What about power factor? Since I'm residential, I know I'm paying for
'real power'. Does this setup measure what I'm paying for?

3) This is a pretty small transformer. I have no specs for it. It seems like
the power through the thing is miniscule. However, I'm slightly worried
about subjecting my refrigerator to this device. Any thoughts on that?

4) I could do some fancy software on a PIC to try and integrate the waveform
in order to get a better approximation of real power in the cases where the
waveform has been mashed by appliances. Is it worth it? Will the shape of
the waveform be preserved through the transformer? Do you know the
percentage difference between this and just using power = Vpeak^2 / 2R?
(which is what I'm guessing my A/C meter does.)

with thanks,
Bob Monsen

 

[default]

On Mon, 6 Oct 2003 06:21:42 -0700, Watson A.Name - "Watt Sun"
<alondra101@hotmail.com> wrote:

I was watching the local ABC News and they had a piece on vampire
appliances. They said that an appliance could be using about 5 watts
when it's turned off, and that's about $4.00 a month. This sounded a
bit high to me. But since I don't get an electric bill, I have no way
to tell.

5 watt-hours times 730 hours a month is 3650 watt-hours or 3.65 kWh.

More than a dollar a kWh?
This is probably good info. if they mean average wasted power around

the house as a result of power supplies idling without doing any work.

I opened up my typewriter some years ago and was surprised at how hot
it was inside. I got my clamp on ammeter and went around the house
measuring everything. Here's some of what I found (calculated on 120
VAC):

CD player OFF 10 watts
Cable amplifier ON:noreading
Cable convertor OFF 16.3 watts
GE TV OFF: no reading
Microwave OFF: 4.3 watts
Sony TV OFF: 12 watts
VCR OFF 14 watts
Computer printer OFF 9.6 watts
Word Processing TypeW 10.0 watts
Police Scanner OFF 3.0 watts
Computer scanner OFF 5 Watts


It amounts to ~$5+ a month for the stuff that doesn't provide any
useful function when off. I think that is significant.

Worth installing a switch for things one uses infrequently.

Wonder how much power that amounts to nationwide?


-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
-----== Over 100,000 Newsgroups - 19 Different Servers! =-----

 

[Lizard Blizzard]

oldsoundguy wrote:
[snip]

my Linear .. Dolby 5.1 amp set up (on all the time) 32'HDTV .. screen

WOW! You must have a theater with a screen that big!

[snip]

--
----------------(from OED Mini-Dictionary)-----------------
PUNCTUATION - Apostrophe
Incorrect uses: (i) the apostrophe must not be used with a plural
where there is no possessive sense, as in ~tea's are served here~;
(ii) there is no such word as ~her's, our's, their's, your's~.

Confusions: it's = it is or it has (not 'belonging to it'); correct
uses are ~it's here~ (= it is here); ~it's gone~ (= it has gone);
but ~the dog wagged its tail~ (no apostrophe).
----------------(For the Apostrophe challenged)----------------
From a fully deputized officer of the Apostrophe Police!

<<Spammers use Weapons of Mass Distraction!>>

I bought some batteries, but they weren't included,
so I had to buy them again.
-- Steven Wright

FOR SALE: Nice parachute: never opened - used once.

(Problem) Evidence of leak on right main landing gear
(Solution) Evidence removed

F
o
d
d
e
r

f
o
r

s
t
u
p
i
d
"
n
o
t

e
n
o
u
g
h

i
n
c
l
d
u
d
e
d

t
e
x
t
"
e
r
r
o
r

m
s
g
..

 

[Tweetldee]

"Robert Monsen" <postmaster@BulkingPro.com> wrote in message
newsEkgb.508681$Oz4.358896@rwcrnsc54...

I have a manutech current sense transformer I picked up from a junk box
buy,
and I've been trying to build a simple kill-a-watt meter. Here is my
schematic:

3 to 2000
| |
| | -----+----------------
+----| | | | | ^
| C|| | C| .-. |
AC C|| | C| | | 100 ohms V Sense
| C|| | C| | | |
+----| | | | '-' |
| | | | v
| | ------+----------------
created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de

Now, this seems to approximately work for the three devices I've tried it
on:

100W light bulb, Vsense = 0.120V, computed power = 94W
25W light bulb, Vsense = 0.028V, computed power = 22W
AC Motor , Vsense = 0.220V, computed power = 167W

However, the question arises whether this will work for appliances.

1) I have a simple A/C meter. Does that do a passable job in this
circumstance?

2) What about power factor? Since I'm residential, I know I'm paying for
'real power'. Does this setup measure what I'm paying for?

3) This is a pretty small transformer. I have no specs for it. It seems
like
the power through the thing is miniscule. However, I'm slightly worried
about subjecting my refrigerator to this device. Any thoughts on that?

4) I could do some fancy software on a PIC to try and integrate the
waveform
in order to get a better approximation of real power in the cases where
the
waveform has been mashed by appliances. Is it worth it? Will the shape of
the waveform be preserved through the transformer? Do you know the
percentage difference between this and just using power = Vpeak^2 / 2R?
(which is what I'm guessing my A/C meter does.)

with thanks,
Bob Monsen

Bob,
What you have there is just a current sensor.. only the beginnings of a
wattmeter. You need a bit more circuitry to get a wattmeter. Consider that
Watts = Volts * Amps. You only have amps (actually, a scaled representation
of amps) from your circuit.
What does that leave? Volts and the multiplication function. There are ICs
that specifically provide a multiplication function; the MC1495 from ON
Semiconductor is the first that comes to mind. There have been several
application notes written specifically to show simple wattmeter designs
around this chip.
Download the spec sheet at
http://www.onsemi.com/pub/Collateral/MC1495-D.PDF. A quick web search
revealed a simple but versatile design for a wattmeter at
http://www.maxim-ic.com/appnotes.cfm/appnote_number/1160/ln/en. You could
use that as a starting point for your wattmeter. You would have to add
higher voltage and current ranges to get the power levels that you're
interested in, and of course, if you want to use your current sensor, you
would want to substitute it in place of the sense resistor in the diagram.
Answering you questions,;
(1) A simple voltmeter on the output of your circuit will only give you a
representation of the curremt being drawn by the load.
(2) No.. Again, you're only measuring current.
(3) Google the web for current transformer design and you'll get a better
understanding of how they work, and how to calculate the current/voltage
relationship.
(4) Forget about using your AC meter for this if you really want to build a
wattmeter. Again, the spec sheet for the MC1495 and

 

[Oppie]

What you've got is a current sense transformer. Since the transformer is
small, the best low frequency response is had by using as low a secondary
terminating impedance as possible. If you don't know what gauge the primary
wire is, it's hard to figure the maximum current that it can take. I usually
go by limiting to a 50C temperature rise.

You can calculate only Volt-Amps if you measure the voltage and then
multiply by your measured current. If you want to measure watts, you would
need to multiply (2 or 4 quadrant) in real time the current and voltage to
take into account the phase angle (power factor).

FWIW take a peek at
http://www.elecdesign.com/Articles/Index.cfm?ArticleID=2191
there are some additionsl links at the bottom of that page.

Oppie

--
For correct response address, remove -nospam-
=========
"Robert Monsen" <postmaster@BulkingPro.com> wrote in message
newsEkgb.508681$Oz4.358896@rwcrnsc54...

I have a manutech current sense transformer I picked up from a junk box
buy,
and I've been trying to build a simple kill-a-watt meter. Here is my
schematic:

3 to 2000
| |
| | -----+----------------
+----| | | | | ^
| C|| | C| .-. |
AC C|| | C| | | 100 ohms V Sense
| C|| | C| | | |
+----| | | | '-' |
| | | | v
| | ------+----------------
created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de

Now, this seems to approximately work for the three devices I've tried it
on:

100W light bulb, Vsense = 0.120V, computed power = 94W
25W light bulb, Vsense = 0.028V, computed power = 22W
AC Motor , Vsense = 0.220V, computed power = 167W

However, the question arises whether this will work for appliances.

1) I have a simple A/C meter. Does that do a passable job in this
circumstance?

2) What about power factor? Since I'm residential, I know I'm paying for
'real power'. Does this setup measure what I'm paying for?

3) This is a pretty small transformer. I have no specs for it. It seems
like
the power through the thing is miniscule. However, I'm slightly worried
about subjecting my refrigerator to this device. Any thoughts on that?

4) I could do some fancy software on a PIC to try and integrate the
waveform
in order to get a better approximation of real power in the cases where
the
waveform has been mashed by appliances. Is it worth it? Will the shape of
the waveform be preserved through the transformer? Do you know the
percentage difference between this and just using power = Vpeak^2 / 2R?
(which is what I'm guessing my A/C meter does.)

with thanks,
Bob Monsen

 

[oldsoundguy]

On Mon, 06 Oct 2003 15:51:06 -0700, Lizard Blizzard <NOSPAM@rsccd.org>
wrote:

oldsoundguy wrote:
[snip]

my Linear .. Dolby 5.1 amp set up (on all the time) 32'HDTV .. screen

WOW! You must have a theater with a screen that big!

[snip]

that was the intent!!

 

[Robert Monsen]

"Tweetldee" <dgmason99@att99.net> wrote in message
news:Kpmgb.171313$3o3.12564034@bgtnsc05-news.ops.worldnet.att.net...

"Robert Monsen" <postmaster@BulkingPro.com> wrote in message
newsEkgb.508681$Oz4.358896@rwcrnsc54...
I have a manutech current sense transformer I picked up from a junk box
buy,
and I've been trying to build a simple kill-a-watt meter. Here is my
schematic:

3 to 2000
| |
| | -----+----------------
+----| | | | | ^
| C|| | C| .-. |
AC C|| | C| | | 100 ohms V Sense
| C|| | C| | | |
+----| | | | '-' |
| | | | v
| | ------+----------------
created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de

Now, this seems to approximately work for the three devices I've tried
it
on:

100W light bulb, Vsense = 0.120V, computed power = 94W
25W light bulb, Vsense = 0.028V, computed power = 22W
AC Motor , Vsense = 0.220V, computed power = 167W

However, the question arises whether this will work for appliances.

1) I have a simple A/C meter. Does that do a passable job in this
circumstance?

2) What about power factor? Since I'm residential, I know I'm paying for
'real power'. Does this setup measure what I'm paying for?

3) This is a pretty small transformer. I have no specs for it. It seems
like
the power through the thing is miniscule. However, I'm slightly worried
about subjecting my refrigerator to this device. Any thoughts on that?

4) I could do some fancy software on a PIC to try and integrate the
waveform
in order to get a better approximation of real power in the cases where
the
waveform has been mashed by appliances. Is it worth it? Will the shape
of
the waveform be preserved through the transformer? Do you know the
percentage difference between this and just using power = Vpeak^2 / 2R?
(which is what I'm guessing my A/C meter does.)

with thanks,
Bob Monsen


Bob,
What you have there is just a current sensor.. only the beginnings of a
wattmeter. You need a bit more circuitry to get a wattmeter. Consider
that
Watts = Volts * Amps. You only have amps (actually, a scaled
representation
of amps) from your circuit.

Thanks for the help. I guess I was assuming the voltage was line voltage,
ie, around 115V. That makes it possible to determine power using only a
current sensor. An essential part of the posted 'wattmeter' was my
calculator...

However, you are right that a better way to determine the voltage across the
device makes sense. Another voltage sensor would be one way, say a small
power transformer. Using that, I can determine the voltage across the line
directly, and use these to generate the display.

Regards,
Bob Monsen

 

[Mark Jones]

In news:e4c7d5068367a73896e1232d660301a0@news.teranews.com (Oppie):

What you've got is a current sense transformer. Since the transformer is
small, the best low frequency response is had by using as low a
secondary terminating impedance as possible. If you don't know what
gauge the primary wire is, it's hard to figure the maximum current that
it can take. I usually go by limiting to a 50C temperature rise.

You can calculate only Volt-Amps if you measure the voltage and then
multiply by your measured current. If you want to measure watts, you
would need to multiply (2 or 4 quadrant) in real time the current and
voltage to take into account the phase angle (power factor).

FWIW take a peek at
http://www.elecdesign.com/Articles/Index.cfm?ArticleID=2191
there are some additionsl links at the bottom of that page.

Oppie

Also very prevalent is this writeup on transformers:
http://www.ibiblio.org/obp/electricCircuits/AC/AC_9.html. Go down past the
middle of the page, there is much useful information there.

I have a manutech current sense transformer I picked up from a junk
box buy, and I've been trying to build a simple kill-a-watt meter.
Here is my schematic:

3 to 2000
| |
| | -----+----------------
+----| | | | | ^
| C|| | C| .-. |
AC C|| | C| | | 100 ohms V Sense
| C|| | C| | | |
+----| | | | '-' |
| | | | v
| | ------+----------------
created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de

Now, this seems to approximately work for the three devices I've tried
it on:

100W light bulb, Vsense = 0.120V, computed power = 94W
25W light bulb, Vsense = 0.028V, computed power = 22W
AC Motor , Vsense = 0.220V, computed power = 167W

However, the question arises whether this will work for appliances.

1) I have a simple A/C meter. Does that do a passable job in this
circumstance?

2) What about power factor? Since I'm residential, I know I'm paying
for 'real power'. Does this setup measure what I'm paying for?

3) This is a pretty small transformer. I have no specs for it. It
seems like the power through the thing is miniscule. However, I'm
slightly worried about subjecting my refrigerator to this device. Any
thoughts on that?

4) I could do some fancy software on a PIC to try and integrate the
waveform in order to get a better approximation of real power in the
cases where the waveform has been mashed by appliances. Is it worth
it? Will the shape of the waveform be preserved through the
transformer? Do you know the percentage difference between this and
just using power = Vpeak^2 / 2R? (which is what I'm guessing my A/C
meter does.)

with thanks,
Bob Monsen

 

[Active8]

In article <blrv6f$ppv$1@news.eusc.inter.net>, jerryg50@hotmail.com
says...

we can do better. run the important stuff in sleep mode and keep it
alive with a super-cap. IR RCVR? eh, might draw a bit too much.

All appliances that use a microcontroler for their operation require some
power to be maintained. The off switch on most devices today, only shuts of
the display, and some non required circuitry if that. In the case where
there are motors, heating elements, and other similar types of apparatus
used in the appliances, when in the off mode, these sections are disabled.

In the case of TV sets, the scan circuits, audio output stages, and the
front end tuner are disabled, because the horizontal and HV outputs sections
are disabled. The main processor is still running. Infact on all modern
equipment, where there is a remote control, or any type of auto function,
the microprocessor and its support circuitry must be running to be able to
respond.

There are also many devices where the power switch is purely cosmetic, and
the device is running all the time as normal. They only switch off the front
panel lights, and any displays to make it look like it is off.

yeah, and when that VCR acts stupid, sometime a power-cycle (un-plug it)
is all it takes to get it going again.

I have a Scientific Atlanta digital box for my TV set. When it is turned
off, the time is showing like a clock. Internally, the unit is still working
fully, and the TV will even work on the same channel. It does however not
allow the channels to be changed when in the off mode, but the output is
operating fully. It is pulling about 30 Watts from the AC all the time. I
cannot unplug it from the AC, because I would have to get it re-initialized
by the service provider, and that can take about 15 to 20 minutes each time
I want to use the TV.

then SA must be screwed because Jerrolds/General Instruments and
Panasonic boxes can be unplugged for up to 24hrs without needing to be
re-hit. call warner cable in houston and ask if they don't send boxes
out pre-hit. same for the GI boxes in Balto city except they're not pre-
hit, but you can take them when you move and if you don't screw around
unpacking, it'll not need to be re-hit.

hee, hee... i had an instant (24 hr) install contract through a sales
company in a CATV system once and this customer gave me an SA box she
found when she moved in. hmm... this system uses Panasonic. not warner -
another MSO. after connecting her outside, i checked the channels and
the guide channel wasn't where it should be. i've seen 2 systems on the
same pole or in diff UG peds before, but this wasn't the case. i was on
the border and the MSO's plant info must have been wrong. oh well, it
occurred to me later what was wrong and i let 'em know. (doubt anyone
cared cause i wasn't sent back.)

can you imagine the confusion, finger pointing, and bitching that may
have happened if that customer were to be cut off as an illegal hook up
when she'd been faithfully paying the bill for months or even years
before the tap audit? "i'm sorry maam, i don't show anything indicating
a turn-off order. are you sure your TV is connected to the box?"

Infact, the instruction manual indicates that the
unit can be left on all the time. There is no difference.

All your modern electric clocks that use an LED display will draw about 5 to
8 Watts on the average.

must be those blasted XFMRs. good case for off-line switchers?

Microwave ovens and TV sets will draw the same
amount when in the off mode.
If you have an electric stove or any device
that has an electric clock and or a remote control to switch the power on
and off will also draw this amount. This also includes all models of
cordless phones.

but the wal-wart helps keep the place warm ! think of the savings in
heating fuel. [if you ask me,] heat pumps rule. - words added for
poetic/musical purposes - why rhyme if it isn't properly syncopated,
right?

In the province of Quebec, Canada, electric power costs an average of about
$0.04 US or $0.06 Cdn per kW/Hr. The typical home has about 10 devices that
draw about 6 Watts AC average when in the off mode. This is about 60 Watts
of power being used all the time. This is 0.06 kW each hour. This works to
about This works to about $0.06 US per day, or about $0.09 Cdn per day of
electricity. This is not very bad, considering the total cost per month of
operating a home.

and leaving that computer on with the monitor off (unless you need the
heat) reduces the thermal cycling on the big-chip.

The only other solution is to purchase all 1960's or earlier appliances and
devices for your home, if you can find them. You will be spending all your
time scrounging for parts and continuously fixing them. Infact, the old
1960's electric clocks with motors in them, required more current to operate
than today's modern LED and LCD clocks. The earlier appliances when
operating required much more wattage to get the same job done, therefore,
you will not win with this situation.

good! now if all the old wiseacres would hurry up and die, we might see
a higher revenue per capita in modern stuff.

brs,
mike

--

Greetings,

Jerry Greenberg GLG Technologies GLG
=========================================
WebPage http://www.zoom-one.com
Electronics http://www.zoom-one.com/electron.htm
Instruments http://www.zoom-one.com/glgtech.htm
=========================================


"Watson A.Name - Watt Sun" <alondra101@hotmail.com> wrote in message
news:MPG.19eb0c30ca01a8a7989770@news.dslextreme.com...
I was watching the local ABC News and they had a piece on vampire
appliances. They said that an appliance could be using about 5 watts
when it's turned off, and that's about $4.00 a month. This sounded a
bit high to me. But since I don't get an electric bill, I have no way
to tell.

5 watt-hours times 730 hours a month is 3650 watt-hours or 3.65 kWh.

More than a dollar a kWh?

 

[Active8]

In article <blshj4$4c9ak$1@hades.csu.net>, NOSPAM@rsccd.org says...

Jerry G. wrote:

[snip]

Infact, the old
1960's electric clocks with motors in them, required more current to operate
than today's modern LED and LCD clocks.

The quartz sweep second hand clocks run for a year off a single AA cell.
So no power at all needed from the wall outlet.

The earlier appliances when
operating required much more wattage to get the same job done, therefore,
you will not win with this situation.

One of the ladies at work replaced her old fridge with a new energy
efficient one. Her electric bill went down fifty dollars a month(!)

wow! my GM replaced her toiled with a "water-saving" one. it takes 2-3
flushes to do the job. OTOH, my uncle got one that seems to have the
same sized tank. that bad boy can flush some serious... has to be the
design. the water comes out with authority, much like some of the stuff
that goes in the bowl.

brs,
mike

 

[Active8]

In article <jgj3ovk2aien2qq8ghjq9educ4srqb4fjg@4ax.com>, soundguy2
@worldnet.att.net says...

On Mon, 06 Oct 2003 13:02:09 -0700, Lizard Blizzard <NOSPAM@rsccd.org
wrote:

Jerry G. wrote:

[snip]

Infact, the old
1960's electric clocks with motors in them, required more current to operate
than today's modern LED and LCD clocks.

The quartz sweep second hand clocks run for a year off a single AA cell.
So no power at all needed from the wall outlet.

The earlier appliances when
operating required much more wattage to get the same job done, therefore,
you will not win with this situation.

One of the ladies at work replaced her old fridge with a new energy
efficient one. Her electric bill went down fifty dollars a month(!)

Old refrigerators and freezers wasted most of their energy in
generating heat, which if in a confined room, would lower the
efficiency of the unit itself, yet alone run the ambient temp of the
room up to an un livable level, requiring the need for an air
conditioner of some sort.

the russians put their crypto vaults in little rooms and tried to cool
the vault with an A/C. poor clerks didn't stay very cool and some
developed leukemia from the high power noise the KGB (commo directorate
branch) pumped in for anti-tempest purposes.

I have a full blown media room .. full stereo system (where the main
amp/pre amp is ON but display is off all the time .. phono pre amp for
my Linear .. Dolby 5.1 amp set up (on all the time) 32'HDTV .. screen
is the only thing that turns off, so it generates heat .. two
computers (P iv's) that generate a gang of heat (did go to an LCD
display which cut down on the heat from a monitor.

my 21" heats a 7x12 room in winter even with the a/c unit in the window
with half-assed weather seal. why do i even have double pane windows?

.. but all along
the back wall behind a vented folding door set is a pantry, which
includes a huge side by side ref/freezer. so I have to have an 8000
btu air conditioner running 9 months out of the year. plus a Honeywell
Air cleaner to keep from having to open and CLEAN everything every
month!

at least my CPUs have a fan to force the air through the coffee filters
that keep the above implied dust out.

brs,
mike
>