[time-nuts] FE-5680A tear down on Youtube

[Peter Gottlieb]

You can buy cheap ceramic room heaters which worh this way. 


Peter

On Jan 18, 2012, at 11:38 AM, Bob Smither <smither at c-c-i.com> wrote:

> Attila Kinali wrote:
>> On Fri, 13 Jan 2012 12:50:19 -0500
>> "Bob Camp" <lists at rtty.us> wrote:
>> 
>>> The gizmo on top of the crystal is a rapid transition thermistor. The
>>> Russians came up with them for use in OCXO's back in the 1970's. It's there
>>> to heat the VCXO crystal, sort of an OCXO.
>> 
>> Do you have any references to this? I couldn't find anything on the net.
>> 
>>                Attila Kinali
> 
> From http://wb9ipa.qrpradio.com/60meter/osc_filter/osc_filter.htm :
> 
> "PTC thermistors exhibit a unique behaviour, in that their resistance increases
> as the temperature increases.  This temperature to resistance relationship is
> very non-linear; in fact, the change becomes very rapid above a temperature
> known as the Transition Temperature.  This property can be exploited to make a
> very simple, self-regulating heater."
> 
> See also http://c-c-i.com/node/165 for an application note that has a pretty
> good discussion of this.
> 
> -- 
> Bob Smither, PhD                                   Circuit Concepts, Inc.
> =========================================================================
>   Friendly relations with all nations, entangling alliances with none.
>     --Thomas Jefferson
> =========================================================================
> Smither at C-C-I.Com  http://www.C-C-I.Com  281-331-2744(office)  -4616(fax)
> <smither.vcf>
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