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Posted by Don Foreman on April 26, 2008, 11:59 am
Please log in for more thread options wrote:
>
>> On Fri, 25 Apr 2008 23:33:18 -0500, Richard J Kinch
>>
>>>grumpyoldhori writes:
>>>
>>>> Is it feasible to use two of these wires to carry twelve
>>>> volts that distance ?
>>>
>>>No.
>>
>> I'd say yes.
>
>Probably need to start with 24 volts to get 12 at the top. It will have
>about 15+ ohms total resistance (~3000 feet of wire). Is the load constant?
>Like a lamp or such?
>
>Is the wire insulated from the wood post? He could use 24 volts AC to a
>transformer at the top and convert to DC at the end.
>
>Tom
>
I figure 7.7 ohms for 1000 meters of 4 millimeter iron (steel) wire,
so drop of about 3.9 volts at 0.5 amp. I'd find a source of 16 to 24
VDC for the drive end, put a 12-volt regulator (e.g. LM7812) on the
load end. The regulator costs about a dollar. It'll need a bit of
heatsink, perhaps a piece of ally 10 cm square or so. It can be bent
as desired to fit in a space.
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> volts that distance ?