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Re: testing NTC caps

From Clive Arthur <cliveta@nowaytoday.co.uk>
Newsgroups sci.electronics.design
Subject Re: testing NTC caps
Date 2017-02-08 16:56 +0000
Organization A noiseless patient Spider
Message-ID <o7figq$lqm$1@dont-email.me> (permalink)
References <iclk9cp9l3b7oidhpb2asjuaap7snjdhmj@4ax.com> <o7fccp$t70$1@dont-email.me> <vq-dncjOcPvF1gbFnZ2dnUU7-K-dnZ2d@supernews.com>

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On 08/02/2017 16:47, Phil Hobbs wrote:
> On 02/08/2017 10:12 AM, Clive Arthur wrote:
>> On 07/02/2017 23:36, John Larkin wrote:
>>>
>>>
>>> We special-ordered a reel (4000 pieces) of NTC caps from Capax. They
>>> are 0805, 3.3 pF, N4700. 23 cents each.
>>>
>>> I figured I should test them. I made an oven out of a roll of solder,
>>> with the cap and a thermocouple inside.
>>>
>>> https://dl.dropboxusercontent.com/u/53724080/Parts/Caps/NTC_Setup.JPG
>>>
>>> It has a nice long thermal time constant. I started with a heat gun to
>>> get it to 50C, covered it with a cloth, and took data slowly as it
>>> cooled. Near room temp, a spritz of freeze spray into the solder coil
>>> cooled it down, and then I took data as it slowly warmed up.
>>>
>>> https://dl.dropboxusercontent.com/u/53724080/Parts/Caps/NTC_Data.JPG
>>>
>>> The measured tempco is close to -7000, but that's OK. I'm going to
>>> compensate a 600 MHz coaxial ceramic resonator oscillator, with this
>>> cap and a series NPO padder, so too-high tempco is OK.
>>>
>>> It would be great to have a very small benchtop oven, peltier
>>> hot/cold, to test small parts or circuits.
>>>
>>>
>> I use a vacuum flask with wadding in the neck.  I use a small aquarium
>> bubbler pump to pump air through silicone tubing via a power resistor
>> (one with a cooling tube through the middle) through the wadding to the
>> bottom of the flask.  A cheap Chinese PID controller and solid state
>> switch to heat the resistor closes the loop.
>>
>> It's nice and even, low power and can be left on for days.
>>
>> Cheers
>
> A bit tough to cool with that setup, though.

Just connect the resistor the other way round.

> Cheers
>
> Phil Hobbs

Cooling is much harder because of condensation, at least for boards or 
components.  With my setup, and using a stainless flask, I can run at 
200'C without problems.


Cheers
-- 
Clive

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Thread

testing NTC caps John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-02-07 15:36 -0800
  Re: testing NTC caps Lasse Langwadt Christensen <langwadt@fonz.dk> - 2017-02-07 15:41 -0800
  Re: testing NTC caps Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-02-07 19:40 -0500
    Re: testing NTC caps John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-02-07 17:18 -0800
      Re: testing NTC caps "tom" <tmiller11147@verizon.net> - 2017-02-08 00:21 -0500
        Re: testing NTC caps John Larkin <jjlarkin@highlandtechnology.com> - 2017-02-08 08:41 -0800
      Re: testing NTC caps "Tom Del Rosso" <fizzbintuesday@that-google-mail-domain.com> - 2017-02-08 02:41 -0500
    Re: testing NTC caps bill.sloman@ieee.org - 2017-02-07 19:15 -0800
  Re: testing NTC caps Clive Arthur <cliveta@nowaytoday.co.uk> - 2017-02-08 15:12 +0000
    Re: testing NTC caps Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-02-08 11:47 -0500
      Re: testing NTC caps Clive Arthur <cliveta@nowaytoday.co.uk> - 2017-02-08 16:56 +0000
        Re: testing NTC caps Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-02-08 12:04 -0500
    Re: testing NTC caps John Larkin <jjlarkin@highlandtechnology.com> - 2017-02-08 08:49 -0800
      Re: testing NTC caps Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-02-08 11:57 -0500
        Re: testing NTC caps John S <Sophi.2@invalid.org> - 2017-02-08 13:02 -0600
          Re: testing NTC caps Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-02-08 16:14 -0500
            Re: testing NTC caps John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-02-08 13:28 -0800
      Re: testing NTC caps Jeff Liebermann <jeffl@cruzio.com> - 2017-02-08 11:40 -0800
      Re: testing NTC caps Spehro Pefhany <speffSNIP@interlogDOTyou.knowwhat> - 2017-02-08 18:08 -0500
  Re: testing NTC caps Jeff Liebermann <jeffl@cruzio.com> - 2017-02-08 09:29 -0800
  Re: testing NTC caps Robert Baer <robertbaer@localnet.com> - 2017-02-08 21:45 -0800
    Re: testing NTC caps John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-02-09 11:20 -0800
      Re: testing NTC caps Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> - 2017-02-09 14:29 -0500
        Re: testing NTC caps Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-02-09 22:52 +0000
          Re: testing NTC caps pcdhobbs@gmail.com - 2017-02-09 16:58 -0800
            Re: testing NTC caps Tom Gardner <spamjunk@blueyonder.co.uk> - 2017-02-10 09:01 +0000
            Re: testing NTC caps John Larkin <jjlarkinxyxy@highlandtechnology.com> - 2017-02-10 11:39 -0800
              Re: testing NTC caps Spehro Pefhany <speffSNIP@interlogDOTyou.knowwhat> - 2017-02-10 22:49 -0500
        Re: testing NTC caps krw@notreal.com - 2017-02-09 21:18 -0500
          Re: testing NTC caps pcdhobbs@gmail.com - 2017-02-09 18:54 -0800
            Re: testing NTC caps Clifford Heath <no.spam@please.net> - 2017-02-10 14:18 +1100

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