Lurking and Tempcos

[harrybissell at prodigy.net]

If you can't get "thermal mass" the next best thing is to carefully isolate the mass you you have from rapid temperature changes. I wouldn't want to epoxy a $10 tempco (or whatever the price is...) to a $1 transistor array. Too much chance you will want to upgrade later...
I epoxied mine to a MAT-01 (analog devices) ina little plastic "cup". Not much chance I'll want to improve that transistor...

:^) Harry


 ---- On Dec 14 scottc at zeno.com (Scott Chicoine) wrote: 
> Thanks for the info, Harry (and PaulS and RoyT and RoryMcD).
> 
> I think I might try out your heater some time later, Harry, but I think I'll
> just go with a tempco solution.  It's only one component and doesn't need
> near the PCB real estate a properly controlled heater does.  Besides, Paul's
> got 'em, so what the heck.  :)
> 
> About the "thermal mass":  I assume this is to keep the device from changing
> temperature too rapidly, keeping the diff amp and the resistor from
> heating/cooling at different rates?  I was planning on just making a little
> clip from copper sheet that would go from under the CA3046, up and over the
> side and along the top to end in a little curly-Q that I would stick the
> tempco in, along with a small amount of thermal grease.  Kind of like a
> paper clip.  I'm a little spooked at the idea of potting the thing, it's so
> _permanent_.
> 
> -ScottC
>