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Re: testing NTC caps

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On Wed, 8 Feb 2017 15:12:08 +0000, Clive Arthur
<cliveta@nowaytoday.co.uk> 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

I'd like to go from 0 to maybe 80C. I guess the ideal oven would be a
small box that I can put my circuit inside, that would ramp slowly
from high to low temp. If I don't want to bother to automate the
measurements, I could use a kitchen timer to alert me every, say, 10
or 20 minutes to walk over to my bench and take my data. These
measurements are better if the temperature changes slowly, and that
makes this sort of thing tedious.

Our big oven will sweep temp, and even can be remotely controlled, but
it's a big deal to get wires in and out of the chamber, from DUT to
instruments. It's great for big-deal automated measurements of whole
products, with custom software.



-- 

John Larkin         Highland Technology, Inc

lunatic fringe electronics 

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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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