Various Transistors Tested for Ic and Vce(sat)

[Watson A.Name - Watt Sun, Dark Remover]

[email protected] mentioned... [snip]

Can you write a technical description of how that circuit works?

Pretty sad "design".

Well, yeah - hey it's simple. The URL for the whole project,
including a technical explanation of circuit, is at
http://www.elecdesign.com/Articles/Index.cfm?ArticleID=5886

If Electronic Design isn't the authority, then who else can you trust?
;-)

...Jim Thompson

Electronic Design an authority? ROTFLMAO!

Well, that's why I included the smiley.

Particularly got a kick out of "There's a limitation..." ;-)

That's nothing more than an *inaccurate* hand-waving.

The purpose of asking for the data-taking was to cause your mind to do
a little correlation and then some further thought ;-)

For instance... what *is* saturation and what determines when a
transistor will come out of saturation?

...Jim Thompson

IIRC, saturation is the point where Ic has reached its maximum value,
and further increases in Ib won't increase Ic. THe .7 or so V between
emitter and base (assuming an NPN) is a half volt or more greater than
the < .2V collector to emitter, so the collector-base junction is on
the verge of being forward biased. So more and more collector current
'leaks' into the base.

When the collector-base junction is no longer forward biased, then the
transistor is no longer in saturation.

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[Watson A.Name - Watt Sun, Dark Remover]

You are the first person to note that the device comes out of
saturation based upon *BETA*! *NOT* the saturation rating of the
transistor!

Congratulations!

I tried to give Watson some measurement hints, but he ignored them,
citing Electronic Design as the "authority"... ROTFLMAO!

Authority? These were submitted to them by readers, ElecDesign had
little to do with them. That's why I put the smiley in there.

When Vce(sat) at higher currents is low, it minimizes the amount of
power wasted in the transistor. Better efficiency.

I've said that transistors like the 2N3904 don't have good beta holdup
at higher currents. The 2N4401, BC338, and ZTX651 have increasing
beta holdups at higher currents.

...Jim Thompson

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[Jim Thompson]

[email protected] mentioned... [snip]

You are the first person to note that the device comes out of
saturation based upon *BETA*! *NOT* the saturation rating of the
transistor!

Congratulations!

I tried to give Watson some measurement hints, but he ignored them,
citing Electronic Design as the "authority"... ROTFLMAO!

Authority? These were submitted to them by readers, ElecDesign had
little to do with them. That's why I put the smiley in there.

ISTR that the editor glowingly endorsed the "design".

When Vce(sat) at higher currents is low, it minimizes the amount of
power wasted in the transistor. Better efficiency.

I've said that transistors like the 2N3904 don't have good beta holdup
at higher currents. The 2N4401, BC338, and ZTX651 have increasing
beta holdups at higher currents.

You are *wrong* in using the term "beta holdup at higher current".
But if you had said the 2N3904 has a lower beta than the ZTX651 you
would have been correct.

...Jim Thompson

 

[Jim Thompson]

[email protected] mentioned... [snip]

The purpose of asking for the data-taking was to cause your mind to do
a little correlation and then some further thought ;-)

For instance... what *is* saturation and what determines when a
transistor will come out of saturation?

...Jim Thompson

IIRC, saturation is the point where Ic has reached its maximum value,
and further increases in Ib won't increase Ic.

^^^^^^^^^^^^^^^^^
CAN'T increase collector current due to OTHER circuit restraints.

Re-evaluate your statement for the case of VCE = 10V, for instance.

THe .7 or so V between
emitter and base (assuming an NPN) is a half volt or more greater than
the < .2V collector to emitter, so the collector-base junction is on
the verge of being forward biased. So more and more collector current
'leaks' into the base.

Actually more *base* current "leaks" into the collector, killing the
base drive.

When the collector-base junction is no longer forward biased, then the
transistor is no longer in saturation.

That is a correct statement.

...Jim Thompson

 

[Chuck Harris]

Hi Jim,

Electronic Design used to have a design hints contest, and
one of the hints contained this design snippet:

+5V
|
|
O
|
O
|
+------some gate or another...
|
O
|
O
|
|
GND


-Chuck Harris

Jim Thompson wrote:
TFLMAO!

 

[Mjolinor]

Hi Jim,

Electronic Design used to have a design hints contest, and
one of the hints contained this design snippet:

+5V
|
|
O
|
O
|
+------some gate or another...
|
O
|
O
|
|
GND


-Chuck Harris

Labelled as what, an incendiary trigger mechanism?

No it's the self destruct off the Enterprise (buttons more than 6 ft apart
please), needs two people to authorise.

 

[John Popelish]

Labelled as what, an incendiary trigger mechanism?

No it's the self destruct off the Enterprise (buttons more than 6 ft apart
please), needs two people to authorise.

I have used something very close to that on a low power micro
circuit. The big difference was that the switches were the normally
open and normally closed sections of a single snap switch. The micro
input capacitance held the last closure voltage until the other switch
closed the first time. No bounce and no current consumption, except
for capacitive charging current. And noise immune in both states.

 

[Michael A. Terrell]

Labelled as what, an incendiary trigger mechanism?

No it's the self destruct off the Enterprise (buttons more than 6 ft apart
please), needs two people to authorise.

Where is your sense of adventure? Don't your power supplies have over
current shutdown? ;-)

--
We now return you to our normally scheduled programming.

Take a look at this little cutie! ;-)
http://home.earthlink.net/~mike.terrell/photos.html

Michael A. Terrell
Central Florida

 

[Jim Thompson]

I have posted BetaCurves.pdf on the S.E.D/Schematics page of my
website.

I have run beta (DC, beta=IC/IB) curves for the four transistors that
Watson tried in his (yet another LED driver.

I show beta curves versus current for various VCE conditions.

Hope this is useful.

...Jim Thompson

 

[Tom Del Rosso]

In John Popelish typed:

input capacitance held the last closure voltage until the other switch
closed the first time. No bounce and no current consumption, except
for capacitive charging current. And noise immune in both states.

How is it immune to noise?

 

[John Larkin]

Authority? These were submitted to them by readers, ElecDesign had
little to do with them. That's why I put the smiley in there.

ed has, at the top of every cover,

The Authority on Emerging Technologies for Design Solutions

which is pretty fatheaded considering the actual contents. Most of the
articles are product flacks, and the Design Briefs are usually stupid.

The technology articles often emphasize how hard it is to design
stuff, so you'd be better off just buying it. Pease is down to one or
two interesting columns per year.

And after we almost recovered from everything being a 'solution', now
every other ad screams 'Size Matters'

Snarl. Need more coffee.

John

 

[Spehro Pefhany]

Why shouldn't John (a.k.a. Watson) just hack it. It's his hobby, not
his job. (And we're not in s.e.d, so tapping your MIT Honors ring isn't
going to mean squat).

When he taps it you're supposed to kneel and kiss the ring.

Best regards,
Spehro Pefhany

 

[Tom Del Rosso]

In John Larkin typed:

The technology articles often emphasize how hard it is to design
stuff, so you'd be better off just buying it. Pease is down to one or
two interesting columns per year.

Yeah, it's too bad about Pease. Too much time in Tibet.

Is it even possible for people occupied as writers to have anything to
say about design that you would find useful?

And after we almost recovered from everything being a 'solution', now
every other ad screams 'Size Matters'

It's what you do with your solution that counts.

 

[Jim Thompson]

When he taps it you're supposed to kneel and kiss the ring.

Best regards,
Spehro Pefhany

There ya go! ROTFLMAO!

...Jim Thompson

 

[Jim Thompson]

Why shouldn't John (a.k.a. Watson) just hack it. It's his hobby, not
his job. (And we're not in s.e.d, so tapping your MIT Honors ring isn't
going to mean squat).

Mark Zenier [email protected] Washington State resident

John/Watson/Watt Sun can hack to his heart's content. But what Watson
needs is a little experience in manufacturing to functionality with
minimum cost ;-)

I object to "explanations" that don't fit the facts. So I will post
my objections, and correct the explanations, so that those lurkers
wishing to learn can do so.

Actually, I prefer a world where virtually no one understands *why*
things work... keeps me employed ;-)

...Jim Thompson

 

[Jim Thompson]

[email protected] mentioned... [snip]

I tried to give Watson some measurement hints, but he ignored them,
citing Electronic Design as the "authority"... ROTFLMAO!

Authority? These were submitted to them by readers, ElecDesign had
little to do with them. That's why I put the smiley in there.

ed has, at the top of every cover,

The Authority on Emerging Technologies for Design Solutions

which is pretty fatheaded considering the actual contents. Most of the
articles are product flacks, and the Design Briefs are usually stupid.

But some are down-right hilarious!

The technology articles often emphasize how hard it is to design
stuff, so you'd be better off just buying it. Pease is down to one or
two interesting columns per year.

Yep. He's getting like me, talking more about the Potassium tablets
he's taking than circuits ;-)

And after we almost recovered from everything being a 'solution', now
every other ad screams 'Size Matters'

Hee! Hee!

Snarl. Need more coffee.

John

We just got one of those coffee machines (Cuisinart) that puts the
coffee into a vacuum-bottle carafe. Works great. I'm having a cup
right now that was made 4.5 hours ago... still hot and tasty, not
bitter!

...Jim Thompson

 

[John Larkin]

We just got one of those coffee machines (Cuisinart) that puts the
coffee into a vacuum-bottle carafe. Works great. I'm having a cup
right now that was made 4.5 hours ago... still hot and tasty, not
bitter!

...Jim Thompson

I just walk a block down 9th Avenue to The Beanery. They start foaming
up a latte as soon as they see me walk in the door.

John

 

[John Popelish]

In John Popelish typed:

How is it immune to noise?

In either the up or down state, the input signal is connected directoy
to a supply bus, so capacitively coupled noise goes there, instead of
into the micro. If I used a single switch and a high value resistor
(to save battery current) capacitive noise could easily get to the
micro when the switch was open.

 

[Tom Del Rosso]

In John Popelish typed:

In either the up or down state, the input signal is connected directoy
to a supply bus, so capacitively coupled noise goes there, instead of
into the micro. If I used a single switch and a high value resistor
(to save battery current) capacitive noise could easily get to the
micro when the switch was open.

Gotcha. I thought you meant momentary both ways with a center return,
more like the preceding example with the 2 buttons.

 

[Watson A.Name - Watt Sun, Dark Remover]

I seem to remember some hearing aid toobz that had flexible leads.

...Jim Thompson

Well, here's a 6021 toob that has wire leads, but you can just see a
little bit of them on the left.
http://www.valvediy.com/archives/000018.php
Better pic, and some data
http://amps.zugster.net/projects/sub-mini/


--
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###Got a Question about ELECTRONICS? Check HERE First:###
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My email address is whitelisted. *All* email sent to it
goes directly to the trash unless you add NOSPAM in the
Subject: line with other stuff. alondra101 <at> hotmail.com
Don't be ripped off by the big book dealers. Go to the URL
that will give you a choice and save you money(up to half).
http://www.everybookstore.com You'll be glad you did!
Just when you thought you had all this figured out, the gov't
changed it: http://physics.nist.gov/cuu/Units/binary.html
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