Maker Pro
Maker Pro

looking for a transistor

M

MooseFET

Jan 1, 1970
0
On TO-18 ?

You're quite mad. So, it'll dissipate about 1W now !

It can be done. It is only a 90 degree rise from the case to the
outside of the TO-18. If the ambient is room temperature and the heat
sink is infinite and the transfer is a good heat pipe, it would be
just fine.

On the other hand, you could use the plastic packaged one in a heat
sink and do a little better.

I am really glad that I don't believe him about designing stuff for
the military. I'd rather he worked for the enemy.
 
E

Eeyore

Jan 1, 1970
0
MooseFET said:
It can be done. It is only a 90 degree rise from the case to the
outside of the TO-18.

Where do you get that figure from ?

The data I posted shows a thermal resistance fom junction to case of
146C/W.

Graham
 
C

ChairmanOfTheBored

Jan 1, 1970
0
NO.

Let's face it. You're no designer.

There is no "let's", idiot. You are all alone, and wrong.
God's design + wrong data = Eeyore

If you were any more retarded someone would have to spoon feed you your
dinner as well, idiot.
 
C

ChairmanOfTheBored

Jan 1, 1970
0
It can be done. It is only a 90 degree rise from the case to the
outside of the TO-18. If the ambient is room temperature and the heat
sink is infinite and the transfer is a good heat pipe, it would be
just fine.

On the other hand, you could use the plastic packaged one in a heat
sink and do a little better.

I am really glad that I don't believe him about designing stuff for
the military. I'd rather he worked for the enemy.

You're an idiot.
 
E

Eeyore

Jan 1, 1970
0
ChairmanOfTheBored said:
There is no "let's", idiot. You are all alone, and wrong.

Trying to deny the facts on the datasheet again ?

Do you get a kick out of being WRONG all the time ?

Graham
 
E

Eeyore

Jan 1, 1970
0
Tim said:
Really? I was wondering if I could build a class AB power amplifier with
transistors like ZTX651 and -751. Are you saying it's a good idea then?

Why would you build any amplifier where you intended to **overload* *
the
transistors ? It's important to operate devices with their SOA. And
TO-220s
are no different in that regard.

Graham
 
T

Tim Williams

Jan 1, 1970
0
Eeyore said:
then?

Why would you build any amplifier where you intended to **overload* *
the
transistors ? It's important to operate devices with their SOA. And
TO-220s
are no different in that regard.

Are they? TO-220 power devices work quite nicely in a 10W class AB
amplifier. Do you think I could use the ZTX parts for the same
application?

Tim
 
J

John Larkin

Jan 1, 1970
0
I agree. The 2N2222 parts have Kovar or some other iron
alloy leads (gold plated, perhaps) of very low thermal
conductivity, compared to copper, and for the base and
emitter mounted in the can with glass seals. The collector
lead is welded to the can, but the alloy is still the same
low conductivity stuff the other two leads are made of. The
chip wire bonded to the base and emitter leads, so those
don't even have much of a thermal connection to the die
inside the can. Many TO-92 parts have punched copper lead
frames, especially the Zetex E-line, with the die mounted
directly on a flag on the collector lead. Solder that lead
to a large area pad on the board, with a short lead length,
and you carry away more heat than all 3 leads of the metal
can might carry. Plus the thermally conductivity epoxy
carries heat off all the surfaces of the die not bonded to
the collector tab, where the 2N2222 has the die in an
otherwise empty can, so only the collector side has a local
heat sink.


Just for fun:

A typical TO-92 has 18 mil leads. If pure copper, that corresponds to
just about 400 K/w per inch of lead length, per lead.

John
 
E

Eeyore

Jan 1, 1970
0
John said:
Just for fun:

A typical TO-92 has 18 mil leads. If pure copper, that corresponds to
just about 400 K/w per inch of lead length, per lead.

And they're not copper of course, so more than that.

Graham
 
E

Eeyore

Jan 1, 1970
0
Tim said:
"Eeyore" wrote

I have built Class AB audio line driver stages using TO-92 BC184s and BC
214s not dissimilar to the ZTXs you mention. They work fine.

Are they? TO-220 power devices work quite nicely in a 10W class AB
amplifier. Do you think I could use the ZTX parts for the same
application?

If you did you'd be outside their SOA wouldn't you ?

Are you even thinking about what you say ? Do you know what SOA is ?

Graham
 
J

John Popelish

Jan 1, 1970
0
John said:
Just for fun:

A typical TO-92 has 18 mil leads. If pure copper, that corresponds to
just about 400 K/w per inch of lead length, per lead.

Maybe a good reason to mount them close to the board. A 0.1
inch long copper collector lead soldered into a large copper
area can suck quite a bit of heat.
 
T

Tim Williams

Jan 1, 1970
0
Eeyore said:
If you did you'd be outside their SOA wouldn't you ?

Are you even thinking about what you say ? Do you know what SOA is ?

Stop stalling, you know very well they have a nearly square SOA.

Do you think I could use the ZTX parts for the same application?

Tim
 
E

Eeyore

Jan 1, 1970
0
Tim said:
Stop stalling, you know very well they have a nearly square SOA.

Do you think I could use the ZTX parts for the same application?

Which application ?

If they don't have the required dissipation, obviously not. Are you
COMPLETELY stupid ?

Graham
 
T

Tim Williams

Jan 1, 1970
0
Eeyore said:
Which application ?

Uh? You quoted the very words "ten watt class AB amplifier".
If they don't have the required dissipation, obviously not. Are you
COMPLETELY stupid ?

No, but you must be. We began this subthread with "I wish they made
TO-220's that could handle overload".
You flat out *denied* that there was any advantage to TO-220 devices in
terms of power handling.
So, I proceeded to give you a very specific example where that power
capacity *would* matter.
You responded, utterly confused, as if the sky had just fallen.

So tell me, IS there any advantage of E-line vs. TO-220 devices with
respect to overload capacity (the ability to withstand continuous
dissipation of, say, 10W or more)?

Tim
 
E

Eeyore

Jan 1, 1970
0
Tim said:
Uh? You quoted the very words "ten watt class AB amplifier".


No, but you must be. We began this subthread with "I wish they made
TO-220's that could handle overload".
You flat out *denied* that there was any advantage to TO-220 devices in
terms of power handling.

NO !

I denied there was any advantage in terms of *OVERLOAD* handling. There is a
HUGE difference between an 'overload' and long-term power handling.

Personally I don't *overload* transistors and I suggest you don't either unless
you want failures.

Stop talking nonsense.

Graham
 
M

Michael A. Terrell

Jan 1, 1970
0
Eeyore said:
Stop talking nonsense.


If you ever followed your own advise, you could never speak, write or
type again. :(


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida
 
M

Michael A. Terrell

Jan 1, 1970
0
Eeyore said:
IDIOT = Eeyore


Yes, you are but it doesn't stop you form posting your drivvel. :(


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida
 
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