Marriage is under fire!!

John Popelish wrote:
Kevin Aylward wrote:

John Popelish wrote:
anonymous wrote:

I get the naming difference - what are the different uses for each?
IE why would one use one vs another?

Fet is field effect transistor, the generic name for a gain device
based on the electrostatic modulation of conductivity in the channel
between source and drain.

JFET is a junction fet. The isolation between gate and channel is a
reverse biased PN junction. These are depletion only devices
(normally on, turned off by gate bias voltage).

Usually, but not only. There are a few exceptions:)

Aren't there always? :)
Click to expand...
No:)

Kevin Aylward
salesEXTRACT@anasoft.co.uk
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.
 
Kevin Aylward wrote:
John Popelish wrote:
Kevin Aylward wrote:

John Popelish wrote:
anonymous wrote:

I get the naming difference - what are the different uses for each?
IE why would one use one vs another?

Fet is field effect transistor, the generic name for a gain device
based on the electrostatic modulation of conductivity in the channel
between source and drain.

JFET is a junction fet. The isolation between gate and channel is a
reverse biased PN junction. These are depletion only devices
(normally on, turned off by gate bias voltage).

Usually, but not only. There are a few exceptions:)

Aren't there always? :)

No:)
Click to expand...
Damn. Another rule with an exception.

--
John Popelish
 
In message <QBL5d.524334$M95.17571@pd7tw1no>, Don Kelly
<dhky@peeshaw.ca> writes
The problem there is that even if one gets a good reading of a magnetic
field or an electrical field in any direction, most don't know what to do
with the data or what it means.
The cynic in me would suggest that's because there's no 'what to do'
Click to expand...
with the data, just a bunch of paranormal cobblers.
Also, there must be care taken in the actual
measurements- for example waving a handheld device around will not get you
good electric field measurements as ones body distorts the local field.
Of course, but that's not to say the OP couldn't use a handheld device
Click to expand...
in a static location.
--
Clint Sharp
 
John Fields wrote:
On 26 Sep 2004 06:44:40 -0700, smpaladin@yahoo.com (smpaladin) wrote:

As for the rest of it, until you can more clearly describe what the
parts look like, electrically, and what you really want to do, you're
just pissing in the wind.
Click to expand...
"It's all coming back to me now", said the blind man as he peed into the
wind..

--
 
I ran across an old electronics book, the beginning chapters of which
deal with light emitting diodes. it described the problem of blue
LEDs; IIRC, the distance between the poles determines the color, but
when you get them far enough apart to make blue light, current no
longer flows between the poles.

Am I remembering correctly, and how was the problem solved?
Click to expand...
Must have been an old book, the problem was allways getting the right material
to make them, now we have UV leds as well. The Xray led is still a way offf yet
though.
 
"guy-jin" <guyvf@usa.net> wrote in message
news:774e24ad.0409281409.260b5f16@posting.google.com...
I ran across an old electronics book, the beginning chapters of which
deal with light emitting diodes. it described the problem of blue
LEDs; IIRC, the distance between the poles determines the color, but
when you get them far enough apart to make blue light, current no
longer flows between the poles.

Am I remembering correctly, and how was the problem solved?
Click to expand...
By one man Shuji Nakamura

http://www.businessweek.com/1999/99_24/b3633068.htm

Adam
 
Austin,

Many things have changed since you were frozen in the 60's. And yes,
Liberace was gay.

Bob

"guy-jin" <guyvf@usa.net> wrote in message
news:774e24ad.0409281409.260b5f16@posting.google.com...
I ran across an old electronics book, the beginning chapters of which
deal with light emitting diodes. it described the problem of blue
LEDs; IIRC, the distance between the poles determines the color, but
when you get them far enough apart to make blue light, current no
longer flows between the poles.

Am I remembering correctly, and how was the problem solved?
Click to expand...
 
On Wed, 29 Sep 2004 00:19:48 +0100, "Adam Aglionby"
<nws@capersville.co.uk> wrote:

"guy-jin" <guyvf@usa.net> wrote in message
news:774e24ad.0409281409.260b5f16@posting.google.com...
I ran across an old electronics book, the beginning chapters of which
deal with light emitting diodes. it described the problem of blue
LEDs; IIRC, the distance between the poles determines the color, but
when you get them far enough apart to make blue light, current no
longer flows between the poles.

Am I remembering correctly, and how was the problem solved?
Click to expand...
It's the semiconductor bandgap, not the physical dimensions, that
determines the color.

By one man Shuji Nakamura

http://www.businessweek.com/1999/99_24/b3633068.htm

Adam
Click to expand...
I think the Cree SiC blue led's predated these, but they were
horrendously inefficient: they needed something like 3 volts, 50 mA to
be a decent panel indicator. Paralleled 74S38s + 27 ohms from 5 volts!

But where do they use blue traffic lights?

John
 
John Larkin wrote...
Adam Aglionby <nws@capersville.co.uk> wrote:

guy-jin wrote ...
I ran across an old electronics book, the beginning chapters of which
deal with light emitting diodes. it described the problem of blue
LEDs; IIRC, the distance between the poles determines the color, but
when you get them far enough apart to make blue light, current no
longer flows between the poles.

Am I remembering correctly, and how was the problem solved?

It's the semiconductor bandgap, not the physical dimensions, that
determines the color.

By one man Shuji Nakamura
http://www.businessweek.com/1999/99_24/b3633068.htm

I think the Cree SiC blue led's predated these, but they were
horrendously inefficient: they needed something like 3 volts, 50 mA to
be a decent panel indicator. Paralleled 74S38s + 27 ohms from 5 volts!
Click to expand...
The modern high-efficiency blue (and white) LEDs also require 3V, as
determined by the band-gap voltage like you said. But they give more
light at lower currents. These days all the rage is purple LEDs, for
a much much more impressive light-color sensation.

But where do they use blue traffic lights?
Click to expand...
Isn't purple needed for low-rider under-the-car lighting?


--
Thanks,
- Win

(email: use hill_at_rowland-dotties-org for now)
 
On 28 Sep 2004 19:51:47 -0700, Winfield Hill
<Winfield_member@newsguy.com> wrote:

John Larkin wrote...

Adam Aglionby <nws@capersville.co.uk> wrote:

guy-jin wrote ...
I ran across an old electronics book, the beginning chapters of which
deal with light emitting diodes. it described the problem of blue
LEDs; IIRC, the distance between the poles determines the color, but
when you get them far enough apart to make blue light, current no
longer flows between the poles.

Am I remembering correctly, and how was the problem solved?

It's the semiconductor bandgap, not the physical dimensions, that
determines the color.

By one man Shuji Nakamura
http://www.businessweek.com/1999/99_24/b3633068.htm

I think the Cree SiC blue led's predated these, but they were
horrendously inefficient: they needed something like 3 volts, 50 mA to
be a decent panel indicator. Paralleled 74S38s + 27 ohms from 5 volts!

The modern high-efficiency blue (and white) LEDs also require 3V, as
determined by the band-gap voltage like you said. But they give more
light at lower currents. These days all the rage is purple LEDs, for
a much much more impressive light-color sensation.
Click to expand...
Every couple of years we have to write ECOs to change the
current-limit resistors on a lot of our products that use blue LEDs.
They keep getting more efficient, and customers complain that our
front-panel lights are blinding them. We must average about 5 mA these
days, down from 50 with the old Cree parts.

John
 
In article <jq7kl0tn106j1cgllt87f1tkgrlpubmekp@4ax.com>,
John Larkin <jjlarkin@highlandSNIPtechTHISnologyPLEASE.com> wrote:

On Wed, 29 Sep 2004 00:19:48 +0100, "Adam Aglionby"
nws@capersville.co.uk> wrote:


"guy-jin" <guyvf@usa.net> wrote in message
news:774e24ad.0409281409.260b5f16@posting.google.com...
I ran across an old electronics book, the beginning chapters of which
deal with light emitting diodes. it described the problem of blue
LEDs; IIRC, the distance between the poles determines the color, but
when you get them far enough apart to make blue light, current no
longer flows between the poles.

Am I remembering correctly, and how was the problem solved?

It's the semiconductor bandgap, not the physical dimensions, that
determines the color.


By one man Shuji Nakamura

http://www.businessweek.com/1999/99_24/b3633068.htm

Adam



I think the Cree SiC blue led's predated these, but they were
horrendously inefficient: they needed something like 3 volts, 50 mA to
be a decent panel indicator. Paralleled 74S38s + 27 ohms from 5 volts!

But where do they use blue traffic lights?

John
Click to expand...
Blue plus yellow equals green...

--
Don Bruder - dakidd@sonic.net - New Email policy in effect as of Feb. 21, 2004.
Short form: I'm trashing EVERY E-mail that doesn't contain a password in the
subject unless it comes from a "whitelisted" (pre-approved by me) address.
See <http://www.sonic.net/~dakidd/main/contact.html> for full details.
 
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