vampires and power usage

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I never hear the royal "we" but I'm often forced to hear reference to the football "we" all the time. As in "we were robbed" mouthed by people who haven't kicked a ball since they were kids.
-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on http://home.graffiti.net/diverse:graffiti.net /
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writes

Ian.
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Ian Jackson wrote:

They were real low grade shit. They were replaced by backmatched taps when systems were extended past the original 12 channel systems in the US. They caused mismatch problems, and wasted a lot of the signal on the trunklines or feeders. They worked, more or less on systems with just a few channels, and very few customers, but them, those people were already used to ghosting and snow. They had all been pulled from the 17 systems around Ft Rucker by 1972, including a couple short haul feeds that only had a couple channels.
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non-directional (ie just resistive tap-offs, with no directional coupler)? Ian.
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Ethernet required a direct connection to the conductor of the cable, if I remember correctly. The receiver side was high impedance, so it didn't present a significant load to the signal, and the vampire tap was designed to create only a small hole through the shield and inner dielectric so it wouldn't produce much of an impedance bump. Plus the cable was marked with rings to indicate where you could put a tap without having multiple taps end up a multiple of a wavelength apart.
When transmitting, an Ethernet transceiver acted as a current source, putting a fair bit of current into the 25 ohm load (50 ohm cable heading off in each of 2 directions). If two transceivers decided to transmit at the same time, the high DC level on the cable was used to detect a collision.
Original Ethernet used a baseband signal, and on a moderate-sized network every station listened to every other one directly. There's no "head end" to echo upstream signals back downstream again. There's no notion of "upstream" and "downstream".
    Dave
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Ian Jackson wrote:

Here, they were called "Stinger taps" and I had an unused tap block and stinger, along with the strand clamp and drop hook in my toolbox, until at least 2001. It might still be around, but I haven't used that toolbox in so many years that i don't remember. I brought it home the day i was laid off, then I was declared disabled, and unable to work, so it has been under one of my benches here at home, ever since.

Actually, there are two types of coaxial networking that used 75 ohm cable. The simple, small network like Dave describes below witch were non directional, and one that is usually part of a community loop where pairs of one forward channel, and one return channel are used for data, with a heterodyne signal processor at the headend to upconvert the return channel to a forward channel witch is built with back matched taps.
This system predates the current cable modems, but used standard, off the shelf CATV components to build a private WAN along with the RF modems. Some were mixed systems, of RF fed to clusters of the simpler coaxial networking. The first system like that I heard about was the Ohio State University campus in the '70s or early '80s. Their private CATV system connected all the buildings, then tied the existing, smaller networks together. I met two of their IT people at a hamfest, and they were bragging about their design, till I told them about the systems I maintained for the US army, years earlier. There was no return channel equipment on the market, so we had a pair of 12 channel 'Vicoa' (Later called Coral) systems set up as forward and return to carry the weather data from an airfield to the main base where it added to the other nine forward channels that fed the classrooms and airfield ready rooms.
We also built the first emergency alert system into a CATV system that took control of the civilian CATV service to the barracks and on base housing. A custom made coaxial relay was added to the existing system to seize control of the private system. The ETV studio was 12 channel, like the civilian system. A toggle switch (with a hinged cover and a lead seal) would feed the same audio and video to all 12 modulators, and switch the remote relay so an alert could be spread, no matter what channel a TV was on. After we proved the concept, it quickly spread to other bases, and new builds of civilian systems. The last system I maintained was a 36 channel RCA headend, in the early '80s. It had the optional IF loop through and auxiliary IF input for the alert system. The Audio and video was fed through a separate modulator with a IF output amp, instead of a channel module. I rewired the rack by strapping the loss of signal output to the relay control, and connected diodes to isolate each channel from the emergency control system. I also looped the emergency video through the local access control room so I could flip one switch and feed the same signal to all 36 channels in an emergency.
The loss of signal mod caused a message to appear a half second after the carrier dropped out from a TV station, or satellite feed. That let the tech on night shift check the alignment of the converters after stations signed off, at night.
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(Snipped because I found it less-relevant-than-I-expected to the subject line)
I was expecting to see stuff about power consumption by "wall warts".
Those have been called "vampires" by being 2-pronged/"fanged" constant consumers of small amounts of electrical energy that can become somewhat significant in terms of electrical energy consumption if one has several being powered 24/7, though this is well behind a refrigerator and behind most climte control and lighting electricity demand.
I do believe that there should be some "energy efficiency" requirements of those. I find many "switchmode" cell phone chargers to do well in that area, as I estimate from their heat output when loaded (mostly somewhat less than that of wallwarts" with iron core physical transformers) and when unloaded or largely-unloaded (they become outright cool to the touch when being connected to a cellphone that has detected that its battery got fully charged).
I also see many "wallwarts" with more-traditional iron core transformers easily consuming a watt or two less apiece if they get made with heavier gauge wire, more turns of wire per unit area of wound-around-core-cross-section, and/or thinner core material laminations preferably of some decent material - preferably "29M6" or only one or two minor steps cheaper than that. Maybe requiring next larger size (usually step up in most-traditional inch measurements for an "E-I" transformer core has longest dimension upped 5/16 inch, another upped 1/4 inch and the third upped 1/8 inch, and there are often some options to more mildly increase only the "stack thickness" of a laminated core by 1/8 inch that will even alone fairly often do well).
- Don Klipstein ( snipped-for-privacy@misty.com)
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Everything which plugs into a wall socket has to have THREE pins. The live and neutral receptacles have safety shutters, which are moved aside as the ground pin (which is somewhat longer) enters. Even in the UK, no self-respecting vampire would use three teeth. Ian.
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Don Klipstein wrote:

Then tell me why you didn't reply in a more appropriate part of the thread? I was answering some questions from another poster.
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That was where the thread started when I first saw it. Either my news server went screwy for a while or I failed to notice the thread before.
I now see that there were earlier articles having to do with power supplies that are constantly plugged in.
- Don Klipstein ( snipped-for-privacy@misty.com)
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On Sun, 17 Jun 2007 14:46:43 +0000 (UTC), snipped-for-privacy@manx.misty.com (Don Klipstein) wrote:

Part of the thread is in alt.home.repair AND sci.electonicts.repair.
Another part is only in ahr.
I think I brought in ser, and the answers about wall warts are in the other part of the thread.

You read ser iirc. So it's not that your server is screwy or that you failed to notice.
There is almost always a third possibility, even though often people (I'm not referring to you) don't want to believe it (Either it's amnesty or it's deportation)

OH, I should have read this sentence first. OOPs. To find the posts in ahr, you should come with the subject name and the date, because there is so much traffic on Ahr that it will be hard to find otehrwise. Or use groups.google and the exact subject name.
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I was reading ahr. I could have glanced too quickly through a range of subject lines towards the end of the alphabet. I scan through subject lines more carefully in the range starting with "C", "F" and "L" since I pay more attention to lighting and fluorescent lamps than to most other stuff that comes up in ahr.
- Don Klipstein ( snipped-for-privacy@misty.com)
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On Fri, 15 Jun 2007 09:00:18 +0100, Ian Jackson

England has loads of slang that the USA doesn't use. Most of which we've never heard. Ask about this on alt.english.usage and the English posters there can give you lots of stuff.
I think you are in the position I'm in in our respective countries, knowing few or no people who recent slang. Old slang doesn't capture our attention because we know what it means.

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Hi,
On some of these smaller power supplies there is no transformer at all! I.E. no primary and secondary. They do have an inductor that is used to step down the power and rely on a Thysistor (aka. electronic switch) to turn on an off very fast. Usually 60 times a second (ac mains frequency). The voltage regulation is dependent on the amount of time the switch is on during the power cycle.
http://en.wikipedia.org/wiki/Switched_mode_power_supply
One nice thing about this is that they can adapt to many mains voltages and mains frequency. Hence for laptop computers you only need one "International" power brik like supply.
Warmest regards, Mike.
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Power Vampires are a significant problem. While each one is (usually) not significant, altogether they can add up to quite a bit. I have found that they can add up to several hundred watts. "Kill-a-watt" can be quite useful if you can guess where they all are and they are plug-in devices. As you can see, not all plug in the wall. Here are some idle power consumptions that I have measured:
Doorbell transformer 8 watts cordless phones 4-9 watts DirecTV receiver (off) 34 watts TV (off) 17 Garage door opener 2.5 Fax machine 10 Gas furnace 20 Newer gas furnace 27 Central AC outdoor unit 20-40 watts (two different units)
Other devices to consider: Any device with a remote control (stereo, DVD player, X-10, etc.) Any portable device with a rechargeable battery: (cordless phones, toothbrush, vacuum, drill, etc.; cell phones) Timers of any sort (irrigation, lights, etc.) UPS for your computer. DSL modem motion activated lights
200 watts continuous is 144 KwH per month. That's hundreds $ per year!
Zephyr wrote:

http://gizmodo.com/gadgets/gadgets/california-passes-vampire-slayer-act-181497.php
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wrote:
These are the sort of things that bother me.

I don't understand this one. Have AC's changed, or do all brands have this, and what is outside that is using current when the AC isn't running? Are we talking about 12 months a year?

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mm wrote:

Yes, we are talking 12 months a year unless you turn off the breakers.
One of the ACs was a 4 Ton Carrier unit. The power was consumed by a 40 watt "crankcase heater". These are more common in larger (4, 5, or more ton) AC condensers (outdoor units), those that are a longer distance from the indoor unit, those that use R-410a, and in heat pumps. Sometimes they are thermostatically controlled. This one was not.
The other is a 3 Ton Trane 2-stage condenser. The 20 watts appeared to be consumed by a variable speed fan controller. This one is totally inexcusable, as an added relay would pay for itself in less than 1/2 a year.
These are the sort of things that California's Vampire Slayer bill (which appears to have not become law) that the OP referred to might embarrass manufacturers into cleaning up.
Note: some of the power consumption figures that I mentioned were apparent power (measured in "Volt-Amps" -- the vector sum of real power and reactive power) because it was easier to measure, and some were in real power (measured in Watts). Kill-A-Watt measures both. Residential power meters generally measure real power. The cost to the utility is somewhere in between.
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It's pretty bogus to add up VA power numbers as if they were watts, then calculate how much you would pay per year. If your meter measures real power (and as you say, it probably does), then the cost depends on the real power consumed.
For things with resistive heaters, real and apparent power are about the same and it doesn't matter. But for something like half of the loads you listed, the power is probably almost all magnetising current in a transformer, with a very low power factor. For these loads, the real power is a fraction of the apparent power, and using apparent power will produce a large error.
    Dave
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wrote:

OK. It's not that my system is all that matters, but it's all that I control, I would be upset if it were in my control to stop wasting electricity and I didn't. None of these factors apply to me, except maybe R-410a if that is the old stuff, and I'm pretty certain I don't have a crankcase heater.

I don't have a variable speed fan controller either. My outdoor fan has one speed, and my indoor fan has one of three speeds, set by connecting wires.
But I'll have to upgrade someday and now I'll know to turn my AC off at the breakers after that, for the 11 or 10 months a year I don't use it.

Sounds inexcusable

I'd like to better understand that and what Dave said. I once asked about the difference between volt-amps and watts and didn't get a real answer iirc. I haven't googled.
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To calculate watts, you take instantaneous measurements of voltage and current and multiply them together, then integrate (average) the result over some time period. You can do this in analog circuitry using an analog multiplier device, or you can do it digitally by making many measurements of voltage and current per cycle and multiplying them digitally before filtering. Either way, you need a special meter that measures and multiplies two quantities instant by instant.
To calculate volt-amps, you measure and integrate voltage and current separately, then multiply the two numbers together. This can be done with two independent ordinary multimeters.
If the load is resistive (e.g. an oven, baseboard heater, etc) there is no difference between watts and VA. The current is always in phase with the voltage, the product of the two is always positive, and the two different calculation methods give the same answer.
But that's not true of capacitive and inductive loads. In capacitive loads, the current waveform is up to 90 degrees in phase ahead of the voltage waveform (i.e. peak current happens as voltage passes through zero, where its rate of change is greatest). If the phase shift is exactly 90 degrees (pure capacitance), then for half of the cycle the sign of the current and voltage are actually different, and the product of the two is negative for that portion of the cycle. The same is true for inductive loads (e.g. transformer with no load on it, unloaded motor) except the current waveform lags the voltage one by up to 90 degrees.
Whenever there is a phase shift between current and voltage, the VA remains the same, but the watts measured are reduced. Effectively, for one portion of the AC cycle the circuit accepts power from the utility, and for another portion of the cycle it feeds some of that power back to the utility. If the phase shift is a full 90 degrees (either ahead or behind), the net power is zero!
Both measures are important. Watts is the amount of actual power consumed by your device and converted into heat, light, or mechanical motion. Voltage determines the amount of insulation needed on wires and the number of turns of wire in a transformer, while amps determine the size of wire needed to carry the current and the resistive losses in that wire resulting from current flow.
So VA is generally the right measure to use when sizing transformers and wiring, not watts.
    Dave
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