Cheap USB analog interface?

[Don Lancaster]

For years, I've had this ISOPOD back burner project going. The concept
was a tennis ball shaped object you could ( reasonably safely ) clamp on
one of your input ac power lines and it would transmit your current (
and thus more or less your power ) consumption on a sampled-fairly-often
basis.

I'm wondering if a demo cannot be built up using stock parts at
reasonable costs. The Fluke i2500 looks like a good (but pricey) front end.

Question: What is a reasonably cheap analog to wireless USB stock
product? Or preferably stock analog to wireless to web? Can it be
powered from a current transformer? What reception software would be
involved? Can javaScript on the web do it?

The whole point is that smart power meters seem slow coming locally,
and that many smart meters will be "closed' rather than "open access"
devices. Some means is needed to safely sample power consumption for
energy awareness. Without needing an electrician or meeting specs. Two
units would likely be needed, one for each 110 volt arm of the 220 volt
input.

Yes, the sensor might be ahead of the meter. But the total power
"stolen" would be miniscule and the utility benefits would be major.

If the data rate was high enough, power factor could also be sensed.
Even without, the current consumption should be a most useful metric.

--
Many thanks,

Don Lancaster voice phone: (928)428-4073
Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
rss: http://www.tinaja.com/whtnu.xml email: [email protected]

Please visit my GURU's LAIR web site at http://www.tinaja.com

 

[Martin Riddle]

For years, I've had this ISOPOD back burner project going. The concept
was a tennis ball shaped object you could ( reasonably safely ) clamp
on one of your input ac power lines and it would transmit your current
( and thus more or less your power ) consumption on a
sampled-fairly-often basis.

I'm wondering if a demo cannot be built up using stock parts at
reasonable costs. The Fluke i2500 looks like a good (but pricey) front
end.

Question: What is a reasonably cheap analog to wireless USB stock
product? Or preferably stock analog to wireless to web? Can it be
powered from a current transformer? What reception software would be
involved? Can javaScript on the web do it?

The whole point is that smart power meters seem slow coming locally,
and that many smart meters will be "closed' rather than "open access"
devices. Some means is needed to safely sample power consumption for
energy awareness. Without needing an electrician or meeting specs. Two
units would likely be needed, one for each 110 volt arm of the 220
volt input.

Yes, the sensor might be ahead of the meter. But the total power
"stolen" would be miniscule and the utility benefits would be major.

If the data rate was high enough, power factor could also be sensed.
Even without, the current consumption should be a most useful metric.

Define cheap

www.microdaq.com The HoBo stuff does usb wireless.

I have not seen a small ADC --> USB logger that's cheap. Would be
useful tho.
I've done a PIC USB HID and its not that difficult.

Cheers

 

[Martin Riddle]

You can always go with a USB host uC and USB WiFi adapter. However,
software for WiFi adapter is not simple.

That would require a TPC/IP stack, or maybe just UDP.

Here's a Dataq logger for $29
<http://www.dataq.com/products/startkit/di145.html#ordernow>
You just need a wireless interface.

Cheers

 

[Don Lancaster]

Define cheap

www.microdaq.com The HoBo stuff does usb wireless.

I have not seen a small ADC --> USB logger that's cheap. Would be
useful tho.
I've done a PIC USB HID and its not that difficult.

Cheers

What National Instruments is not.

--
Many thanks,

Don Lancaster voice phone: (928)428-4073
Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
rss: http://www.tinaja.com/whtnu.xml email: [email protected]

Please visit my GURU's LAIR web site at http://www.tinaja.com

 

[hamilton]

Which one? Any link?

Its kind of funny that a few years ago, Wireless USB was the rage.

Today the usb.org has changed the Wireless USB to a "good idea":
http://www.usb.org/developers/wusb/

PCs have Bluetooth or 802.11 as standard wireless interfaces.

802.15.4 (Zigbee) seems to be a custom solution, but lots of people are
making them.

So, there is really no wireless standard that's cheap.

hamilton

 

[hamilton]

For the wireless USB stuff, I would look at one of the TI ez430s. They
start around 50 bucks.

http://www.ti.com/corp/docs/landing/mcu/index.htm?DCMP=MSP430&HQS=Tools+OT+ez430

Here is a power meter built with one.

http://ceit.uq.edu.au/content/wireless-power-meter

The cheapest wireless "standard" interface would be Zigbee.
A serial Zigbee interface is <$20.
I have played with:
http://www.sparkfun.com/products/10253

I was able to send messages over 20 feet indoors.
PCs can only connect to one of these devices at a time though.

The TI parts should be able to connect in a network, so many devices
should be able to communicate with the host.

I have not found any projects out there that have used these parts,
however there are other projects using wireless networks.

A quick google search found:
http://en.wikipedia.org/wiki/Sensor_node

Mesh networking may be a good way to get low power remote data logging.

hamilton

 

[Martin Riddle]

Or reliable enough. I guess it's OK for the OP, since he is only
interested in monitoring the line. However, my goal is to inject
power at the proper phase angle. If it's off, it could be getting
300V
+ voltage mismatch. So, i don't really trust USB (wired or wireless)
in the control loop.

This $29 microchip module looks intriguing
<http://www.microchip.com/wwwproducts/Devices.aspx?dDocName=en548014>

400 meter range. I'm guessing 802.11 b

Cheers

 

[mike]

For years, I've had this ISOPOD back burner project going. The concept
was a tennis ball shaped object you could ( reasonably safely ) clamp on
one of your input ac power lines and it would transmit your current (
and thus more or less your power ) consumption on a sampled-fairly-often
basis.

I'm wondering if a demo cannot be built up using stock parts at
reasonable costs. The Fluke i2500 looks like a good (but pricey) front end.

Question: What is a reasonably cheap analog to wireless USB stock
product? Or preferably stock analog to wireless to web? Can it be
powered from a current transformer? What reception software would be
involved? Can javaScript on the web do it?

The whole point is that smart power meters seem slow coming locally,
and that many smart meters will be "closed' rather than "open access"
devices. Some means is needed to safely sample power consumption for
energy awareness. Without needing an electrician or meeting specs. Two
units would likely be needed, one for each 110 volt arm of the 220 volt
input.

Yes, the sensor might be ahead of the meter. But the total power
"stolen" would be miniscule and the utility benefits would be major.

If the data rate was high enough, power factor could also be sensed.
Even without, the current consumption should be a most useful metric.

By far, the cheapest/easiest solution is to buy a BlueLine wireless
power monitor...or one of the clones from Black&Decker etc.
Cost about $25 on ebay or $15 at garage sales/swapmeets.
It watches the wheel go around or the blinking light on digital meters.
They also have a computer interface, but it's substantially more money.

If you have a digital meter with a light, it's trivial to write a program
for a 25-cent PalmIII to watch the light and log/graph the data.
I'd planned to update the code to a newer palm with bluetooth
for wirelessness. But, I found that, after a few days of monitoring,
the new wears off and the desire for fancier features wanes.

Once you figger out where the power is going, you do what you can
to mitigate it and you're done.
Doesn't do much good to monitor it if there's nothing more you're
willing to do about it.
You don't need data to know to take shorter showers or turn down the heat.

The blueline tells you what you need to know and has some resale
value when you're done.

 

[mike]

The Kill-A-Watt has been hacked to do this.
http://www.ladyada.net/make/tweetawatt/

problem with a killawatt is that you measure what you can plug in.
The things that take the most power are hard wired, or 220V split
across 2 phases...at least in the good ole USA.

But the metrology problem is the same. If you aren't using it,
turn it off. If you're not willing to turn it off, it don't
matter how much instantaneous power is being monitored, databased,
graphed, displayed, studied...just don't matter if you ain't
gonna take some action.

I try not to ask questions if the/my future is independent of the answer.

 

[mike]

You don't want to neglect duty cycle in your analysis. A low power
item run 24 and 7 can use a lot of electricity. Further, the thing you
can control tend to be low power. For instance, you could use an intel
atom for your server rather than sold old PC. Old computers are no
bargain. They have low efficiency power supplies. The larger geometry
chips use more power than the newer cores, provided they have some
power management.

One of the shockers in home energy use is the stupid cable box. Some
are 40 watts. If you turn them off, it takes the head end a while to
see your box and bless it.

Yes, but you can determine that in any number of ways.
A KillAWatt is a great tool to have around for about a week.
Once you determine
consumption, you don't need to track it continuously.

I think I spend more for batteries for all my power and temperature
monitors than I save by having current data.

My VCR clock resets on power outage, so I pay the price to leave it
running...at least in fall when there's something on tv to watch.

My 220V stuff, (oven and dryer), pretty much use what they use. I
can't do much to make them more efficient. The washer is a f-ing
Maytag Neptune. Low power and low water use, but a crappy washer.

While we are at it, I hope you saw that report about Energy Star
products not really tested by the government. You just declare the
product to be energy efficient, and you get your star.

Haven't done Energy Star since '94, but from what I'm reading that's
changing
big-time. Third party certification is/will soon be required.
That's gonna make the costs go WAY up. So we pay for increased product
price to get the piece of paper that confirms less energy use. Can't win...

There's a lot you can do to minimize energy usage.
Problem is that most people don't want to live like wilderness campers
to do it.

When you're paying $70/month for the ability to tweet your every emotion
while driving the SUV to get to that $200 "gaga" concert,
it seems pointless to shave a minute off your shower.

 

[hamilton]

The Kill-A-Watt has been hacked to do this.
http://www.ladyada.net/make/tweetawatt/

Another idea:
http://tvwbb.com/eve/forums/a/tpc/f/9270072103/m/7691098906

 

[mike]

You keep bringing up the shower. Are you using electric water
heater? If so, switch to gas heater, it saves electricity.

True, but the objective is to save MONEY.
The cost of a gas water heater plus the cost of getting the
gas to the location plus bringing the whole installation up
to current code, plus the permits plus the ...plus...plus
and based on my water usage, I'd be dead before it paid back.

I use the shower example because it's so wasteful and
something everybody can relate to.
Last time I did the math, it cost me 13-cents to take a shower.
I could cut that by 90% without sacrificing cleanliness.
Heck, when I had a small RV, I'd take a shower every day
and go a week on 18 gallons of water.

But I LIKE standing under the hot water spray. I like it
13-cents worth.

 

[mike]

So does a water heater timer.

You sure about that?
How long do you turn it off at a time?
What's the thermal time constant of the water heater?
My math says that, for a well-insulated heater,
it makes no sense to turn it off unless you're goin' on
vacation.

Gas is the most expensive way to heat

 

[mike]

No one gives a damn what you're doing so don't waste the $70/month,
or the $200 on a gimmick performer.

Read it again.
Nowhere did I use the word "I".
I DID use the word "YOU".
Look around you...
I don't know anyone over age 8...besides me...who
doesn't have at least one smart phone with EXPENSIVE
data plan. Instant gratification is the norm.
Saving a few bux on energy is WAY down the list for
most of the population.