[sdiy] Thermosensitive Chip Resistors

[Brice D. Hornback]

I am looking at the 1k 3300ppm version (DigiKey # P1.0KCHTR-ND) and can only
find a minimum order quantity of 5000.  Has anyone found a part number for
these that can be ordered in significantly smaller quantities?

Thanks,
Brice

----- Original Message ----- 
From: "Ian Fritz" <ijfritz at earthlink.net>
To: "Jay Schwichtenberg" <jays at aracnet.com>; "Synth-DIY"
<synth-diy at dropmix.xs4all.nl>
Sent: Saturday, January 03, 2004 4:50 PM
Subject: Re: [sdiy] Thermosensitive Chip Resistors


> Hi Jay --
>
> These tempcos have been in the Digi catalog for some time now.  There was
a
> previous discussion about them here last spring, which you might want to
> look up.
>
> I measured the temperature dependent resistance on one of the large size
> (0805) 1.8k units, using a special setup with a large Al block for thermal
> stability/uniformity and a calibrated Wheatstone bridge.  I found that I
> had a bit of difficulty with small drifts in the readings, probably due to
> self-heating effects.  The tempco came out OK at about 3350ppm/K.
However,
> the quadratic coefficient of the fit came out several times larger that
for
> other (full-size) tempcos I have measured.
>
> A 10% tolerance in the tempco is typical, although 5% is sometimes
> found.  That's why I developed the dial-a-tempco circuit.
>
> I haven't tried these tempcos in an actual VCO yet, but they should be OK
> unless you are real fussy about drift.  At least they are affordable.
>
>    Ian
>
>
> At 08:35 PM 1/2/2004, Jay Schwichtenberg wrote:
> >I was thumbing (OK, drooling) at the new Digikey catalog I got today. I
> >found these thermosensitive chip resistors in it:
> >
> >http://www.panasonic.com/industrial/components/pdf/AOF0000CE1.pdf
> >
> >Page 865 in catalog T041.
> >
> >They look interesting since some have a PTC of 3300 ppm/C, come in 1K and
> >can fit under a chip. Only issue looks to be the +/-10% tracking
tolerance.
> >Anyone have any ideas if these would be good enought for expo tempco?
> >
> >Thanks
> >Jay
>