[D.I.Y. tempco sensors]

[Harry Bissell]

Mike: Cool Idea. I don't see why the inductance would be a problem to you
(unless you were thinking of using as op-amp feedback?).
Heaven Help You (however) if the relay gets enough "juice" to energize and
close the contacts... the inductance will change A LOT !!! I might have some
around at work, I'll have to give them a try... I just built the TOMG VCO4c
and need a tempco anyway...

Mike I <mirwin1 at istar.ca> wrote:
Has anyone tried using a small DIP reed relay ( some 12V and 24 V models 
have 1000 ohm coils eg. GORDOS 831A-5) for a tempco resistor? These 
could be glued to the top of a CA3046 dip and provide a positive 3900 
ppm temp coefficient which could be adjusted with a resistor to +3400 
ppm. These relays are readily obtainable and cost around $4 US. Probably 
would need to use them in a voltage divider configuration since they are 
probably quite inductive. Bulky, yes, but they give the proper tempco 
(and a lot better than winding your own copper resistors).


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