[sdiy] Panasonic SMT Thermosensitive Resistors

[Ian Fritz]

I've worked with these a little.  Back when Mouser first started carrying 
them I put one into my special temco characterization rig.  I found it hard 
to get stable readings -- whenever I applied or removed the driving current 
the measured bridge voltage had a slow drift over 10 sec or so.  At the 
time I posted that I thought there was some self-heating going on.

By coincidence, just this week I put one into a new filter circuit.  I 
noticed some drifting while tracking the filter, i.e., every time I changed 
the input by a volt it would take some time (again, ~10 sec) for the 
frequency to stabilize.

I wouldn't call this a huge effect, and it probably won't bother you in a 
filter.  But I'd be careful using it in a VCO.  They are inexpensive enough 
that you could series-parallel four of them -- that would probably 
eliminate any drift.

Ian


At 08:47 PM 2/7/2008, David Brown wrote:
>I never did any specific research on these but used two of them on my 
>Mankato filter. I epoxied them directly to the IC and ran wires to the 
>PCB.  I also used them on my Analog Metropolis filter and made a 
>through-hole part to sandwich between the two expo transistors.
>
> From a user standpoint, they work fine.  I have not taken any specific 
> measurements on them. The Mankato stability is quite good and I could not 
> discern any significant drift when beat against my MOTM-300 over 30 
> minutes or so.
>
>http://modularsynthesis.com/magicsmoke/mankato/mse.htm
>
>Dave
>
>At 05:24 PM 2/7/2008, jays at aracnet.com wrote:
>>These are the little SMT resistors that DigiKey carries.
>>
>>At one point there was a discussion on these in the list. Someone was 
>>worried about whether or not there would be self heating issues with 
>>these when used in an expo converter.
>>
>>Anyone did more research into this or done an expo design with them?
>>
>>Thanks much.
>>Jay S.
>
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