Need Negative Temp Coefficient Component for Xmas Lights Slow Turn-on

hrho...@sbcglobal.net

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Dec 9, 2014, 5:10:07 PM12/9/14

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I have a couple of "sealed" devices that apparently have negative temp coefficient devices inside of them that are placed between a power outlet and the lights. The lights start out at 1/3 normal brightness and come up to full level in 5-10 seconds. Soft turn-on means less light failures. I would like to have/make several of these, but I don't know what is inside the boxes and don't really feel like tearing them apart if I don't have to.

Suggestions!

John Robertson

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Dec 9, 2014, 5:22:14 PM12/9/14

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On 12/09/2014, 2:10 PM, hrho...@sbcglobal.net wrote:
> I have a couple of "sealed" devices that apparently have negative temp coefficient devices inside of them that are placed between a power outlet and the lights. The lights start out at 1/3 normal brightness and come up to full level in 5-10 seconds. Soft turn-on means less light failures. I would like to have/make several of these, but I don't know what is inside the boxes and don't really feel like tearing them apart if I don't have to.
>
> Suggestions!
>

Research Thermistors.

John :-#)#

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hrho...@sbcglobal.net

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Dec 9, 2014, 5:28:46 PM12/9/14

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I was being lazy, had hoped for some part numbers <g>.

Maynard A. Philbrook Jr.

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Dec 9, 2014, 5:49:18 PM12/9/14

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In article <70c9883e-dadd-4321...@googlegroups.com>,
hrho...@sbcglobal.net says...

>
> I was being lazy, had hoped for some part numbers <g>.

They call them "NTC Thermistors".

Look at Mouser, you need to estatemate the wattage
your light string uses so you can properly select the
correct one that will create the voltage drop you need
when cold and reduce down to it's minimum value when
hot.

Phil Allison

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Dec 9, 2014, 5:54:32 PM12/9/14

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hrho...@sbcglobal.net wrote:

> I have a couple of "sealed" devices that apparently have negative temp coefficient devices inside of them that are placed between a power outlet and the lights. The lights start out at 1/3 normal brightness and come up to full level in 5-10 seconds. Soft turn-on means less light failures. I would like to have/make several of these, but I don't know what is inside the boxes and don't really feel like tearing them apart if I don't have to.

** The devices are probably "NTC thermistors".

http://www.ampron.com/UploadFiles/Others/20130712150338_50489.jpg

They come in a range of sizes and resistance values.

You need to measure the cold resistance value to establish the latter.

Last time I needed some, I found them on Ebay from dealers in HK.

... Phil

hrho...@sbcglobal.net

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Dec 10, 2014, 12:11:23 AM12/10/14

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Thanks for the info, I'll measure the cold resistance tomorrow, right now the lights are all on.

jf...@my-deja.com

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Dec 10, 2014, 8:33:05 PM12/10/14

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Is this what you want?

http://www.ermag.com/index.cfm?v_link=product_detail&v_key=325
http://www.ermag.com/index.cfm?v_link=product_detail&v_key=326

If you Google "inrush currebnnt limiter", you can also buy the key component form Digikey or Mouser for less than $5.