[sdiy] thermal coupling question

[Oren Leavitt]

Hi Micheal and all,

If I Recall Correctly, somebody on the list constructed a neat little package using an SMT transistor pair and tempco resitor mounted on an 8 pin DIP header.

Thermal tracking is best if the expo and tempco are in good thermal contact with one another. You may get away with simply placing the expo and tempco near one another if the inside of your enclosure is free of drafts or abrupt temperature changes.
On the other hand, expo transistors do tend to generate a very small amount of heat of their own, so it is best to thermally couple them to the tempco.

Yeah - the expo-grease-tempco sandwich approach is ugly, but it does work well.

Oren

-------Original Message-------
From: Michael Schulze <michael.schulze at oberlin.edu>
Sent: 01/21/03 12:05 PM
To: synth-diy at dropmix.xs4all.nl
Subject: [sdiy] thermal coupling question

> 
> I have a question for the group on thermal coupling.

I am building a quad vco based on Jorgen Bergfor's design.  The expo
converter (in my circuit) contains of a tempco resistor and a MAT-02
transistor pair.  The MAT-02 is in a can enclosure - you know - like a
TO-72
but with 6 leads.  The pcb has a space for an 8 pin dip on which Jorgen
assembled smt devices.  Not being an smt whiz I am just assembling my two
huge crude components on an 8 pin dip header.

So my question is how to achieve the best thermal contact.  Do the two
components need to be physically touching or can they just be next to each
other with a dollop of some magical heat conducting compound binding them
(...in the darkness...).  I'd hope to come up with something more elegant
than heat sink grease...

Thanks in advance

>