[GreenKeys] Loop power supplies

[Nick England]

I think the pass tube isn’t equivalent to a fixed value resistor. The
effective R is higher at turn on, lower at steady state. So snappier RL
time constant? Note the grid bias pot is across the load.

This idea has no warranty express or implied - I just woke up.
Nick

On Sun, Mar 4, 2018 at 10:01 PM drlegendre . <drlegendre at gmail.com> wrote:

> IOW it's not a constant-current supply, but rather a high voltage (~300V)
> current-adjustable supply. Ultimately, its behavior isn't much different
> than that of a simple passive rheostat - nor am I exactly sure what
> advantage it provides over the former.
>
> A pair of series-connected rheostats (one coarse, one fine) would seem to
> exhibit roughly the same behavior - a high terminal voltage purveying a
> fixed, adjustable current.
>
> On Sun, Mar 4, 2018 at 4:54 PM, Jeffrey Angus <jdangus at att.net> wrote:
>
>> On 3/4/18 3:51 PM, Nick England wrote:
>>
>>> I didn't really look at it. The text calls it a current regulator and
>>> does say "They have been designed to provide a steep wave
>>> front when keyed to promote more positive action of relay or
>>> magnet operated equipment."
>>>
>> That's the key. It's a current regulator, not a current source.
>>
>> By using a vacuum tube in place of a fixed resistance, it will
>> provide a somewhat faster rise time.
>>
>> But unlike a true current source, it will not provide a fixed value
>> of current for any and all loads. It has to be adjusted each time
>> for a specific load.
>
>
>>
>>
>>
>> --
>> "I am a river to my people."
>> Jeff-1.0
>> WA6FWI
>> www.foxsmercantile.com
>>
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> --
Nick England K4NYW
www.navy-radio.com
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