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Re: [TCML] GF NST,s



Show me the circuit .  Please .
 

    On Saturday, December 1, 2018, 11:10:59 AM CST, Ed <evp@xxxxxxxxxxx> wrote:  
 
 Doug:

     How about trying to give us your ACTUAL circuit - simple but 
complete circuit drawing.  Also, can you experiment using larger 
resistors [less power from NST].

Ed


On 12/1/2018 3:25 AM, Douglas Johnson wrote:
> The resisters [1K 25W nte25w210] on this page are the ones I had, and used.
> https://vetco.net/search/results?q=25+Watt+Resistor
> Thank you all for your comments.
> By the way, this was just a "wonder what will happen if I do this" thing, I
> didn't expect it to work!
> Doug
>
> On Fri, Nov 30, 2018 at 10:12 PM Gary Lau <glau1024@xxxxxxxxx> wrote:
>
>> I donno.  The GFI kicks into action not because too much current is being
>> drawn but because mains current in is not equal to mains current out, i.e.
>> mains current must be leaking, or something else is happening that looks
>> like that.  Too much secondary current cannot be drawn because of the
>> built-in current limiting of the NST shunts.
>>
>> 30 mA flowing through a 1K resistor only drops the voltage by I*R=30 volts,
>> not a significant loss out of 6000V.  That said, resistors in protection
>> networks do get quite warm, so it's possible more current than
>> faceplate-rating is flowing due to core saturation.  But resistors are made
>> to get hot.  Putting an aluminum heat sink on it is probably not necessary
>> and if the R is part of an R-C low-pass filter, could compromise the
>> high-voltage stand-off rating of the resistor.
>>
>>>> All I know is that it works. Take the resisters out, and GF pops.
>> I can't argue with success.  Thank you for reporting this!  After all this
>> blathering on my part, I don't have an alternate explanation for why the
>> presence of the two resistors allows the GF NST to work.
>>
>> Regards,, Gary Lau
>> MA, USA
>>
>>
>>
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>> On Fri, Nov 30, 2018 at 9:16 PM Matthew Deming <mddeming44@xxxxxxxxx>
>> wrote:
>>
>>> I think that I have figured out why your GF NST is working. With a
>> standard
>>> SGTC the start of the discharge looks like a dead short across the NST
>>> secondary. (Pop!) The resistors dissipate enough power to keep it from
>>> looking like a short to the NST. The only drawback is the power eaten by
>>> the resistors is not available to the TC.
>>>
>>> On Fri, Nov 30, 2018, 11:39 AM Douglas Johnson <doug379306@xxxxxxxxx>
>>> wrote:
>>>
>>>> Hi Ed. Standard TC setup, except the {1K 25 Watt power resisters} are
>>>> connected between the NST HV leads and safety gap lugs on the coil.
>>>> Please understand, I have little technical knowledge here I was just
>>>> playing around and it worked! I would hope some of the more technical
>>>> minded members on the list would do a little trial and error with this,
>>> it
>>>> could possibly open a new source of usable NST's, ie [GF NST's] for
>> small
>>>> and moderate coils.
>>>> These power resisters are inexpensive as are aluminum heat-sinks if
>>> needed.
>>>> I wish I had a 12 or 15K GF NST to test out but I do not.
>>>> Thanks for your reply.
>>>> Doug
>>>>
>>>> On Fri, Nov 30, 2018 at 9:05 AM Ed <evp@xxxxxxxxxxx> wrote:
>>>>
>>>>> What's your circuit?
>>>>>
>>>>> Ed
>>>>>
>>>>>
>>>>> On 11/29/2018 6:53 PM, Douglas Johnson wrote:
>>>>>> Gary, I am far from technical when it comes to this stuff as I am
>>> sure
>>>>> you
>>>>>> can see by a lot of my questions! It was just a fluke that I tried
>>> this
>>>>> out
>>>>>> of boredom. All I know is that it works. Take the resisters out,
>> and
>>> GF
>>>>>> pops.
>>>>>> The resisters are similar in appearance to these >
>>>>>>
>> https://www.ebay.com/itm/2Pcs-Wirewound-Ceramic-Cement-Resistor-0-5-1K-Ohm-5-25W-Watt/352350026175?hash=item5209b2b9bf:m:mowqAUe59odwZoiyCa7jxDg:rk:38:pf:0
>>>>>> Maybe it works because, in my ignorance, I didn't know it
>> wouldn't😉
>>>>>> Doug
>>>>>>
>>>>>> On Thu, Nov 29, 2018 at 9:20 PM Gary Lau <glau1024@xxxxxxxxx>
>> wrote:
>>>>>>> I can't comment on your GF working in a TC.  I've not personally
>>> tried
>>>>> it,
>>>>>>> but the prevailing wisdom is that it typically doesn't work in a
>> TC
>>>>>>> application.  I wonder if higher voltage GF NST's are more
>> affected
>>>> than
>>>>>>> lower voltage ones?
>>>>>>>
>>>>>>> The resistors - 1KOhm, 25Watt, 210-what?  What are these for?  It
>>>> sounds
>>>>>>> like they're intended to be part of a protection network, except
>>> that
>>>>>>> resistors must be used with capacitors to form a low-pass filter
>>>>> network.
>>>>>>> By themselves or with safety gaps, resistors serve no protective
>>>>> purpose.
>>>>>>> Regards, Gary Lau
>>>>>>> MA, USA
>>>>>>>
>>>>>>> On Thu, Nov 29, 2018 at 6:22 PM Douglas Johnson <
>>> doug379306@xxxxxxxxx
>>>>>>> wrote:
>>>>>>>
>>>>>>>> I had a 6K GF NST laying around and decided to see if I could use
>>> it
>>>>> on a
>>>>>>>> small TC. I ran a 1K 25w210 wire wound resistor between each leg
>> of
>>>> the
>>>>>>> NST
>>>>>>>> and the safety gap, it worked just fine. I switched the GF 6kv
>> NST
>>>>> with a
>>>>>>>> non GF 6kv nst and the coil output was identical.
>>>>>>>> I was always told that a GF NST would not work for a TC??
>>>>>>>> Resistors are holding up ok.
>>>>>>>> Comments please
>>>>>>>> Doug
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