"new" tempco sensors

[Martin Czech]

I always wondered what these KTY positive temperature coefficient
things are...  now Rene Schmitz pointed us to www.conrad.de where he
bought some other PT tempcos (quite expensive, order number 171778-62,
5 Euro, +0.385%) (thank you, Rene!!)

and I suddenly came across these devices:

Philips: KTY84-xxx order number 183458-62 
Siemens: KTY10x    order number 183440-62
                   order number 183407-62

These guys are quite cheap: About 1.5 Euro.  
Philips specs the tempco to be +0.61% 
Siemens has no spec for that (!!!?), but an app note shows
about +0.5%.

They are not based an metal alloys, but on doped silicon, so they
are not 100% linear, but cheap. I think the nonlinearity is
not that bad at all (0C-100C). Other errors (thermal) may be much larger.

The Philips part looks more interesting to me, it's speced and it's in a
diode glass housing, like an 1n4148. 

Since these are positive tempco devices, they are used in the lower leg (ground leg) for our purposes. The tempco value is too high, but that could be easily changed by a series resistor. This way the tempco could be trimmed.

I think these little things are quite interesting, I should have a look at them.
I need a new 2.2Ohm 25W resistor anyway... better order now.

Rene, you mentioned experiments with the KT-120, I can't find them at conrad any
more (full text search). I guess these silicon things are all more or less the same. What where your results? 


m.c.