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Jun 21 2014

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TO-92 with RaDiAtOrS

How can we squeeze the maximum performance out of small, fragile, TO-92 form factor transistors ?

What if we want to push them to the limit ?  As in a “Brutal Force” input stage ?

P1120004 b

In order to make these, you need:

a). 0,1 mm copper tape or copper sheets

b). SuperATTACK glue (otherwise known as cyanoacrylate acid)

c). Any thin diameter copper wire; I used 0,19 mm diameter.

d). Any other less critical glue, such as Bison for hard plastics, or similar.

P1120008 b

A superglue drop would suffice to make the bonding between the transistor and the copper.

But winding it around with the small diameter copper wire actually helps even out / spread the heat and further facilitate heat transfer and cooling.

The spreading out of heat is especially important if you are creating matched beta transistor pairs, such as for use in a differential stage, or a current mirror stage, or a mirrored cascode stage. Note that some of my “transistors” have six legs. This is because that they are actually paired. One from each side of the copper surface.

P1120006 b P1120005 b

The fins are marked with permanent marker. This is so as to document the type of transistor and its beta (or the beta of the pair).   Comes in handy, since you shall not be seeing the original markings on those transistors any time soon …

P1120003 b P1120002 b P1120001 b P1110999 b

Setting them up on a laboratory perforated board might be tricky.

Luckily I have made them Lop-sided, asymmetrical, so that I could “turn” them around (especially the matched up pairs) so as to direct the fins into areas where there is still some free space …

P1110998 b

This is what the circuit would “look like” without the fins – but that would be too easy, would it not ?

P1110997 b


And besides, at those currents that I intend to push through these transistors, these radiators may actually make the difference of survival or thermal breakdown of those poor tiny little things.

To make a long story short: the brutal force principle can be uniformly applied – big or small – even in the case of the INPUT stage …




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