Biasing/thermal compensation of Thermal Trak transistors

[tvrgeek]

Bummer. Several are still listed. I was about to plug them into my "Reasonable" design.
THis thread should prove handy on the bias issue, internal diodes or not.

 

[Holgi]

Hi there,

need to re-animate this thread since I'm curious how to do it best in my mechanical setup which is as follows:

• Case from modushop.biz with depth=400mm, which means 2 separate 200mm heat sinks per side
• OPS with 6 pairs of OnSemi BJTs, 3 pairs on each heat sink

The attached picture shows the idea: I want to apply 1 TT pair and 2 non-TT pairs per heat sink, but how to setup the compensation then? It's not clear to me, since I cannot make sure both heat sinks are always on the same temperature level. The simplest way would be the 4 TT-diodes in series, but is this the holy grail? I'm open to suggestions 😀


BR,
Holgi

 

[teodorom]

Hi,
did anybody have built this amplifier?

 

[mchambin]

What I would expect from a Thermal Track data sheet is:
Characteristics of the tracking.
That is some data to know about the transfert fonction of this thermal systeme. Where you have as input the power at the Bjt, as ouput the forward voltage at the diode.
What is the delay at the diode when there is a power step at the Bjt ?
What is the time constant about the temperature increase of the Bjt junction when there is a power step ?
What is the time constant about the temperature of the diode junction when there is a temperature step at the Bjt junction ?

It should be clear right away how the diode is thermally coupled to the Bjt.
It is in the same case, but as far as I know it is not on the same die.