Re: gEDA-user: TO-92 Best Practices

[Mark Rages <markrages@xxxxxxxxx>]

On Tue, Mar 2, 2010 at 6:39 PM, Kai-Martin Knaak <kmk@xxxxxxxxxxxxxxx> wrote:
> On Tue, 02 Mar 2010 13:46:31 -0800, Steven Michalske wrote:
>
>> As for the statements that we were being elitist in suggesting SOT-23,
>> I did not intend that, in my experience to-92 in a manufacturing
>> environment today is an avoid.
>
> It proves to be easy for the newbie, too.
> Every once in a while I need to teach completely uninitiated physics
> students how to solder. I get the impression, that decent thru hole
> solder joints need at least as much practice as the basic variants of SMD
> (0805, SOT23, SO8, ...)
>

Right.  This has been my experience too.  SMT soldering isn't really
harder than through-hole, it is just different.  I don't think it is a
big help to beginners to teach them obsolete technology.

Of course the tiny 0402 and such are harder, but they are just harder
to see and pick up, not harder to solder.  Maybe beginners should
learn point-to-point wiring of vacuum tube circuits.  Those are really
easy to see!  You can see them operate and even feel the voltages.
Once.

Back on topic though.  I can see where TO-92 would still have a place
for testing in a socket.  (Although there are SOT23 sockets made, for
PIC10 and EEPROMs in SOT23-6.  These sockets are about $75.)

I have found it essential when using matched pairs of TO-92, to
physically attach the pair together to reduce thermal gradients.  Heat
shrink is OK, epoxy better.  Even then, the match is not as good as a
dual transistor in SMT.

Regards,
Mark
markrages@gmail
-- 
Mark Rages, Engineer
Midwest Telecine LLC
markrages@xxxxxxxxxxxxxxxxxxx


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