Yeah, sorta. AC actually has more line loss than DC, though the difference would be unmeasurable at this distance and power level. AC is used for distribution because (AC) transformers can change voltage efficiently. High voltage power distribution results in lower line current hence lower line loss for given size wire.
In this situation, all that's needed is enough excess voltage at the sending end to make up for about 4 volts of line drop at 0.5 amp. A simple regulator at the load end makes it possible to use any DC source (18 to 24 VDC at 0.5 amp) that's readily available.
One could also use a transformer at the sending end, AC on the wires, rectify and regulate at the load end. Doesn't matter, use whatever's easy and readily available.
Ping Andrew in Oz (VK3BFA) for possible sources of supplies.
Yes, an 0.1 to 1.0 uF 50-volt bypass cap is a good idea. 30-volt TVS (transient voltage suppressors) would handle about all induced lightning surges. Example: 1.5KE30
Also the peak voltage equals the average voltage witch reduces the insulation losses. And the capacity caused current is zero. Therefor the DC line is more efficiency. But the terminal equipment is expensive
Hi Grumpy, a trip away from NZ.gen? I used a car battery with a solar panel charger for a gate opener, which worked well. A car battery (or 2 in parallel for more capacity) is cheap and easy to get and should have enough capacity to run the router for days of darkness. The solar panel was pretty cheap as well for a smaller size, although this was a few years ago. It has the advantage for being portable too, so you are not stuck with having it by a fence.
No, it's steel! The wire is all steel with a (thin) copper plating. That does bring the resistance down, but it is still fairly high compared to all-copper wire. But, with some luck, you might be able to find an entire spool of this stuff that some "army-navy" type store would let you have cheap. But, it might not do a whole lot better than the fence wire.
Phone companies used to use copper clad steel on poles.
Maybe there is some still hanging or some in the phone yard sitting.
I'd talk to them if the phone or power company has scrap line for this type of use. Might find so. Might find a few to help string some of which they provide.
Even a bundle of twisted wire could be used - sets of lines in parallel.
The zinc might not be considered in the estimates either. But it leaches off.
I think myself I'd send AC - 36V at 1/3 the current and voltage drop. Then on top convert that into the 12V. I'd limit to 36 for safety. You might have to post flags warning of voltage present. Much like cattle fences.
Martin
Mart> Stephen Rob>
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On Sat, 26 Apr 2008 13:41:34 -0700, with neither quill nor qualm, Gunner Asch quickly quoth:
Here are eBay-NZ sources for solar panels, Grumps:
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I wonder: at what voltage did they run field phones?
And we find sheep tasty. Fair trade, wot?
-- Happiness in marriage is entirely a matter of chance. If the dispositions of the parties are ever so well known to each other or ever so similar beforehand, it does not advance their felicity in the least. They always continue to grow sufficiently unlike afterwards to have their share of vexation; and it is better to know as little as possible of the defects of the person with whom you are to pass your life. -- Jane Austen, Pride and Prejudice, 1811
Because the mil spec stuff is thinner than heavy fence wire it would be less effective - and he'd only have single strand instead of the capability of using 3 parrallel strands in each direction.
Is this high tensile steel fence wire (AKA electric fence wire) or standard fence wire. The high tensile stuff is thinner. Can't say I've ever measured the stuff, but we used both on the farm years ago,
The old overhead phone wire that used to run from the pole to the house used to be rubber jacketed parallel strand copper plated iron wire. Iron wire was self supporting over 50 feet between poles and did not expand as much and "stretch" in warm weather - or tighten in extreme cold - as much as copper.
Saw a house (26 years ago when shopping for the one I now live in) that had the whole rec-room wired in that stuff!!!!!!! Apparently the former owner was a retired Bell line-man.
Called the electrical Inspection Authority on that one.
Line current starts out at the Central Office as float voltage on
23-cell Lead Calcium wet-cell string (26-cell with the End Cells cut in) - nominal -48VDC but the float voltage goes up to around -52V normally and -55V on Equalize.
When you pick up a phone at home and allow for loop resistive losses, you see about -24VDC effective across the set.
Ring voltage starts out from the CO at around 130VAC, usually 20 Hz.
They run it through 130V 25W light bulbs as a cheap and dirty ballast resistor & trouble indicator - if you ever saw one of those ballast lamps go bright, either you had a big slug of outgoing traffic going through or there was a short somewhere.
Up till a few years ago when the last of the Step and Crossbar mechanical switching was removed, the ring generators could be anywhere from 16Hz to 66 Hz if they still have the old M-G Harmonic or Decimonic ring generators for 4-party lines. The phone sets had frequency sensitive ringers, and they could connect the ringer Tip-Ground or Ring-Ground to double it up for 8-party lines.
Been there, Installed (and removed) That, Still have the 130W American Beauty soldering iron, and the burn scars from it have almost faded away...
It is the old soft wire we call it Num 8, 4 mil (3/16-7/32 inch) in diameter. But it looks like these units will work with voltages of between five and fifteen volts. Current draw is less than that published, around .290 of an amp at twelve volts.
That'd work ... but I don't think minimizing voltage drop or maximizing efficiency is the objective. The objective is to get 12 volts at 0.5 amp at the top of the hill. Ya just need enough push at the bottom to overcome 4 volts or so of drop in the wire that's already in place. A regulator at the top takes care of having a bit more push than necessary, which makes scrounging parts much easier.
6 volts All of my field phones (modest collection) use 4 D batteries.
Ayup
Gunner
Political Correctness is a doctrine fostered by a delusional, illogical liberal minority, and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end.
Having read allthe posts on this thread, Im cross with myself for not thinking it earlier. So this equipment is onthe top of a hill It would be simpler to use some 12 volt car/truck batteries charged up with a 12 v wind generator. Lack of sunshine wont effect it!!. nor darkness of night. Nor lightning induced emf in the fence wires. whats the average wind speed up there? If all you want is .5 amp , then generate 2 amps for half the time will cover any charging losses. The smallest car 12v dc dynamo , from a Morris Minor, I believe youve plenty of thee in NZ. with its associated Lucas regulator and cutout. A 3 ft dia 3 bladed prop will do. Your local met office will have records of wind speed and direction over several years, o will any local airfield or gliding club. Just a thought!!!. Ted Dorset UK
On Sun, 27 Apr 2008 00:24:37 -0500, with neither quill nor qualm, Don Foreman quickly quoth:
All I can say is: SHEEP LIE!
That from:
An Indian was walking down a lone desert highway with some his animals, when he was suddenly approached by a man. Little did the Indian know, the man was a ventriloquist with a sick sense of humor. The man asks the indian: "Hello, may I speak to your horse?".
Indian replies "Horse no talk..."
The man looks at the horse and says "Hello horse, how are you?" to which the horse replied "Man, this guy runs me around all, doesn't feed me jack, makes me sleep outside... I am about to take off on this guy!".
The Indian was astounded! He looked at the man and said "Horse no talk before...".
The man asked the indian if he could talk to his dog. The indian replied "Dog no talk...". The man turned to the dog and said "Hello dog, how are you?" to which the dog replied,"Man, I chase this guy's sheep around all day! And for what??? I sleep outside, eat a few scraps, and get ordered around all day! I am about ready to take off on this guy too!"
The Indian was again astounded... He said in a quivering voice "Dog no talk before...".
The man asked the indian if he could talk to his sheep, to which the indian replied "Sheep lie! SHEEP LIE!"
-- Happiness in marriage is entirely a matter of chance. If the dispositions of the parties are ever so well known to each other or ever so similar beforehand, it does not advance their felicity in the least. They always continue to grow sufficiently unlike afterwards to have their share of vexation; and it is better to know as little as possible of the defects of the person with whom you are to pass your life. -- Jane Austen, Pride and Prejudice, 1811
OK. The wire is the HEAVY stuff. Approx 0.21 inch diameter. ANd you have 6 of them. You will be well under 1 ohm per thousand feet and .29 amp current draw? Throw 12 volts on the bottom end and go for it - with each side sharing 3 wires you won't notice the voltage drop at all. Just be ABSOLUTELY SURE to get some kind of effective spike control on the wire to protect against lightning interference.
see:
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Then on both the supply and load end, put a honking big 16 - 24 volt zener across the line to clamp the voltage.
You ought know by know when the soldering iron rolls off the bench, you let it fall ;)
Nice write up!
Wes
PS I've been burned a few times but no scars.
-- "Additionally as a security officer, I carry a gun to protect government officials but my life isn't worth protecting at home in their eyes." Dick Anthony Heller
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