[GreenKeys] Loop Supply

[Don Robert House]

let me see if my old brain is working...

nicad batteries are 1.25 volts each times 100 equals 125 volts DC

Hmmm... John Burch (SK) would get a kick out of this discussion...

Normal charging voltage for 48 volt CO cells is 52 volts.
Without involving some extra help from George S. Ohm it might be  
easier to use three banks of 35 cells
35 x 1.25 = 44 volt bank x 3 = 132 volts.  Taking into account an  
average loop length of 1000 feet of 24 AWG wire with a resistance of . 
0302 per foot x 1000 = 30.2 Ohms In theory the CO power plant would  
provide about 1.7 amps for charging. #24 wire will also support this  
amount of amperage... However the CO line link circuit limits current  
flow in the loop to somewhere between 20 and 40 milliamps. This being  
considered it would be impractical to try to sustain a 62.5 milliamp  
loop for selector magnets and try to keep 105 nicads charged up.

Back to studying for my General exam.

Don K9TTY


On Mar 11, 2008, at 6:24 PM, Bob Camp wrote:

> Hi
>
> So what's the matter with the "normal"  approach. 100 wet cell  
> nicads wired in series?
>
> Float charge them in banks off of the phone line ....
>
> Bob
>
>
> On Mar 11, 2008, at 12:39 PM, Larry Tighe wrote:
>
>> Enough already of this technical discussion on loop supplies!
>>
>> I think I'll simply plug a bridge rectifier into my AC socket.  A  
>> nice 100 watt lite bulb can limit the current for my magnets.
>>
>> Then, put the TTY machines on old wooden skids.  The radio gear is  
>> even simpler,,,,just cut off the ground pin on the plugs.
>>
>> Simply jump up on the wooden skids so your not grounded and wah  
>> lah, you're on the air.
>>
>> Phooey on transformers....they're for beginners!
>>
>> lar
>> K2JIA
>> www.antiquetelephone.com
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>>
>
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