| Author |
Message |
Scott Newell
Guest
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 Posted:
Thu Dec 01, 2005 1:35 am Post subject:
Re: Unusual functions of cheap parts |
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John Larkin wrote:
| Quote: |
Interestingly, the best avalanchers aren't usually super-fast
transistors, but old klunky things. The Zetex avalanche transistors
have lowish Ft's and are made in Russia, maybe on an old process.
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Is there a known figure of merit that would help select devices types
for fast avalanche breakdown?
--
newell
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Guest
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| Posted:
Thu Dec 01, 2005 1:35 am Post subject:
Re: Unusual functions of cheap parts |
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John Larkin wrote:
<snip quote>
| Quote: | A 2N2369 is a gold-doped NPN, gold-doped to kill storage time and
improve recovery from saturation. I don't recall any PNP device with
gold-doping... or the equivalent.
...Jim Thompson
National Semi's (now Fairchild) 2n5771 was a gold-doped PNP.
ft>=850MHz. For avalanche mode one might try the lower-Vce-rated
PN3640 (12v), or PN3639 (6v).
I might even have notes on this. I tested/compared various BJTs in
avalanche mode some years ago, trying to find the "best." ISTR picking
the 2n2369, both because it was fast, and because it avalanched
reliably where other types wouldn't.
James Arthur
Hi, James,
Interestingly, the best avalanchers aren't usually super-fast
transistors, but old klunky things. The Zetex avalanche transistors
have lowish Ft's and are made in Russia, maybe on an old process.
John
|
Howdy John,
I was unclear: by "...it was fast..." I meant the 2n2369 was one of
the devices with the fastest avalanche edges.
Digging through some of my notes, I don't see the BJT comparison, but
a 2n2222 biased to +100Vce, banged / triggered by a 74HC-series gate,
gave synchronous 750pS risetime pulses. Not very impressive, really,
though good for higher-power stuff than I needed.
Interestingly, I found a 74AC00 driving an MPS2369 was faster & less
trouble: 360pS fall (turn on) time, & 570pS rise (turn off) time, and
no nasty high voltage supplies. It was possibly even a little faster
than measured--at 360pS I was pushing my poor little 7S14 1-GHz
sampling plug-in pretty hard.
Best,
James |
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Rich Grise
Guest
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| Posted:
Thu Dec 01, 2005 1:35 am Post subject:
Re: Unusual functions of cheap parts |
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On Wed, 30 Nov 2005 15:09:49 -0500, Spehro Pefhany wrote:
these days. ;-)
Cheers!
Rich
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Spehro Pefhany
Guest
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| Posted:
Thu Dec 01, 2005 1:35 am Post subject:
Re: Unusual functions of cheap parts |
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On Wed, 30 Nov 2005 21:57:50 GMT, the renowned Rich Grise
<rich@example.net> wrote:
| Quote: | On Wed, 30 Nov 2005 15:09:49 -0500, Spehro Pefhany wrote:
On Wed, 30 Nov 2005 18:23:05 GMT, the renowned Rich Grise
rich@example.net> wrote:
On Tue, 29 Nov 2005 18:00:50 +0100, Henning Paul wrote:
Spehro Pefhany schrieb:
I think I remember something like that, maybe with ground beef.
You mean Labskaus?
http://en.wikipedia.org/wiki/Labskaus
Here in Bremen/Germany we usually leave away the fish and use just Corned
Beef (the brazilian Corned Beef is just fine). And sometimes, you find
diced pickles in it. Tastes even better, then.
Looks a lot like ordinary corned beef hash to me, if a little less
coarsely chopped.
But I wonder why they serve it with one of these?
http://www2.catalognavigator.com/libertyindustries/viewitems/tacky-mats/hand-held-tacky-roll-mop?plpver=1001
;-)
Rich
You could also serve with one of these:
http://upload.wikimedia.org/wikipedia/commons/5/50/BismarckArbeitszimmer1886.jpg
From a cursory search, it looks like it'd be kinda hard to find one
these days. ;-)
Cheers!
Rich
|
He looks like this these days:
http://www.gdh-imports.com/acatalog/04GE01.jpg
Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com |
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Guest
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| Posted:
Thu Dec 01, 2005 1:35 am Post subject:
Re: Unusual functions of cheap parts |
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Jim Thompson wrote:
| Quote: | On Sat, 26 Nov 2005 21:41:06 +0100, Winfried Salomon
wsalomontrashcan@t-online.de> wrote:
Hello Jorgen,
Jorgen Lund-Nielsen wrote:
[.....]
2N2369 for fast pulses.
btw, do you know a standard complementary pnp-transistor for the 2N2369,
such like 2N3905 but with higher ft and less feedback capacitance? It
seems that the manufactorers have almost no data on their internet pages.
mfg. Winfried
A 2N2369 is a gold-doped NPN, gold-doped to kill storage time and
improve recovery from saturation. I don't recall any PNP device with
gold-doping... or the equivalent.
...Jim Thompson
|
National Semi's (now Fairchild) 2n5771 was a gold-doped PNP.
ft>=850MHz. For avalanche mode one might try the lower-Vce-rated
PN3640 (12v), or PN3639 (6v).
I might even have notes on this. I tested/compared various BJTs in
avalanche mode some years ago, trying to find the "best." ISTR picking
the 2n2369, both because it was fast, and because it avalanched
reliably where other types wouldn't.
James Arthur |
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John Larkin
Guest
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| Posted:
Thu Dec 01, 2005 1:35 am Post subject:
Re: Unusual functions of cheap parts |
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On 30 Nov 2005 14:32:29 -0800, dagmargoodboat@yahoo.com wrote:
| Quote: |
Jim Thompson wrote:
On Sat, 26 Nov 2005 21:41:06 +0100, Winfried Salomon
wsalomontrashcan@t-online.de> wrote:
Hello Jorgen,
Jorgen Lund-Nielsen wrote:
[.....]
2N2369 for fast pulses.
btw, do you know a standard complementary pnp-transistor for the 2N2369,
such like 2N3905 but with higher ft and less feedback capacitance? It
seems that the manufactorers have almost no data on their internet pages.
mfg. Winfried
A 2N2369 is a gold-doped NPN, gold-doped to kill storage time and
improve recovery from saturation. I don't recall any PNP device with
gold-doping... or the equivalent.
...Jim Thompson
National Semi's (now Fairchild) 2n5771 was a gold-doped PNP.
ft>=850MHz. For avalanche mode one might try the lower-Vce-rated
PN3640 (12v), or PN3639 (6v).
I might even have notes on this. I tested/compared various BJTs in
avalanche mode some years ago, trying to find the "best." ISTR picking
the 2n2369, both because it was fast, and because it avalanched
reliably where other types wouldn't.
James Arthur
|
Hi, James,
Interestingly, the best avalanchers aren't usually super-fast
transistors, but old klunky things. The Zetex avalanche transistors
have lowish Ft's and are made in Russia, maybe on an old process.
John |
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Winfried Salomon
Guest
|
| Posted:
Thu Dec 01, 2005 1:35 am Post subject:
Re: Unusual functions of cheap parts |
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Hello Jorgen,
Jorgen Lund-Nielsen wrote:
| Quote: |
Winfried Salomon wrote:
Hello Jorgen,
Jorgen Lund-Nielsen wrote:
[.....]
2N2369 for fast pulses.
btw, do you know a standard complementary pnp-transistor for the
2N2369, such like 2N3905 but with higher ft and less feedback
capacitance? It seems that the manufactorers have almost no data on
their internet pages.
mfg. Winfried
Maybe 2N4261 ? Have not looked into the datasheet, but as i remember,
i have seen them sometimes in complementary with the 2N2369
|
the problem is, that it is an rf-transistor and can't be driven at
30V/0.2A, I found a complementary in an old table KTT, the 2N2894A, but
it also has max. 12V, so I find no other than the 2N3906.
If I simulate with the 2N3906, the frequency response is not worse than
with the 2N2894A.
mfg. Winfried |
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Spehro Pefhany
Guest
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Winfield Hill
Guest
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| Posted:
Thu Dec 01, 2005 8:46 am Post subject:
Re: Unusual functions of cheap parts |
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Winfried Salomon wrote...
| Quote: | Jorgen Lund-Nielsen wrote:
Winfried Salomon wrote:
btw, do you know a standard complementary pnp-transistor for the
2N2369, such like 2N3905 but with higher ft and less feedback
capacitance? It seems that the manufactorers have almost no data
on their internet pages.
Maybe 2N4261? Have not looked into the datasheet, but as i remember,
i have seen them sometimes in complementary with the 2N2369
|
That was a high-frequency part for the time, spec'd at 1200MHz...
| Quote: | the problem is, that it is an rf-transistor and can't be driven at
30V/0.2A, I found a complementary in an old table KTT, the 2N2894A,
but it also has max. 12V, so I find no other than the 2N3906.
|
An old Raytheon datasheet says the 2N2894 was doped with platinum.
BTW -- in AoE, we list the 2n5771 as a PNP complement to the NPN
2n5769, both 15V plastic versions of older metal-can parts.
--
Thanks,
- Win |
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Rich Grise
Guest
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| Posted:
Thu Dec 01, 2005 9:28 am Post subject:
Re: Unusual functions of cheap parts |
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On Wed, 30 Nov 2005 17:11:17 -0500, Spehro Pefhany wrote:
| Quote: | On Wed, 30 Nov 2005 21:57:50 GMT, the renowned Rich Grise
rich@example.net> wrote:
On Wed, 30 Nov 2005 15:09:49 -0500, Spehro Pefhany wrote:
On Wed, 30 Nov 2005 18:23:05 GMT, the renowned Rich Grise
rich@example.net> wrote:
On Tue, 29 Nov 2005 18:00:50 +0100, Henning Paul wrote:
Spehro Pefhany schrieb:
I think I remember something like that, maybe with ground beef.
You mean Labskaus?
http://en.wikipedia.org/wiki/Labskaus
Here in Bremen/Germany we usually leave away the fish and use just Corned
Beef (the brazilian Corned Beef is just fine). And sometimes, you find
diced pickles in it. Tastes even better, then.
Looks a lot like ordinary corned beef hash to me, if a little less
coarsely chopped.
But I wonder why they serve it with one of these?
http://www2.catalognavigator.com/libertyindustries/viewitems/tacky-mats/hand-held-tacky-roll-mop?plpver=1001
;-)
Rich
You could also serve with one of these:
http://upload.wikimedia.org/wikipedia/commons/5/50/BismarckArbeitszimmer1886.jpg
From a cursory search, it looks like it'd be kinda hard to find one
these days. ;-)
Cheers!
Rich
He looks like this these days:
http://www.gdh-imports.com/acatalog/04GE01.jpg
|
I was thinking of the "bismark roll", which I had thought was some kind
of jelly donut, or "bismark donut", which would be like a jelly roll.
But I can't find a single reference to the thing except at the wikipedia
disambiguator page, and all it has is the blurb, something like what I
said.
Oh, well. :-)
Thanks!
Rich |
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Henry Kiefer
Guest
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| Posted:
Thu Dec 01, 2005 9:35 am Post subject:
Re: Unusual functions of cheap parts |
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Thank you Jim for your longly explanations. I already knew the charge
storage process, but the phasing aspect was new and interesting.
My question about phase delay was in another direction.
To be concrete:
How to delay (=phase shift) a 145MegHz signal (mostly sinus waveform) with a
snap diode? After reading your explanation I cannot see how to achieve a
non-snapping action here. Maybe that would work with the diode if you
modulate it with dc current getting delay in the ps timescale.
Another question would be if it possible with the snap diode to make a power
amp in some form of ringing oscillator. Of course, it should be modulable at
least with FM.
- Henry
"RST Engineering" <jim@rstengineering.com> schrieb im Newsbeitrag
news:11ornbrrr5mv976@corp.supernews.com...
| Quote: | A step-recovery ("snap") diode works on the principle of stored charge in
the diode. During the forward biased half of the AC waveform, the diode
is
a very low impedance and it stores excess charge; during the reverse
biased
half of the waveform, the diode remains a low impedance until the stored
charge is depleted, at which time the diode "snaps" into high impedance.
This snap acts much like a spark-gap transmitter, in that a tremendous
number of higher order harmonics are generated. In general (and there are
ways to enhance this), the power available from any harmonic is around 1/n
*
Pin, where n is the order of the harmonic and Pin is the RF power input to
the diode.
Biasing the diode simply varies the point on the reverse cycle of the AC
waveform where the diode snaps. For maximum power, you try to get the
diode
to snap at the peak of the waveform. However, by varying the diode bias,
you can get it to snap before or after the peak of the waveform.
Generally
you can get it to snap plus or minus about 30 degrees about the peak
before
the snap action degrades.
60 degrees of phase shift is nothing to talk about unless you are working
with the 10th harmonic, which means a phase shift of 600 degrees. Now
you've got something to work with.
Jim
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Jim Thompson
Guest
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| Posted:
Thu Dec 01, 2005 5:35 pm Post subject:
Re: Unusual functions of cheap parts |
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On 30 Nov 2005 18:46:34 -0800, Winfield Hill
<Winfield_member@newsguy.com> wrote:
| Quote: | Winfried Salomon wrote...
Jorgen Lund-Nielsen wrote:
Winfried Salomon wrote:
btw, do you know a standard complementary pnp-transistor for the
2N2369, such like 2N3905 but with higher ft and less feedback
capacitance? It seems that the manufactorers have almost no data
on their internet pages.
Maybe 2N4261? Have not looked into the datasheet, but as i remember,
i have seen them sometimes in complementary with the 2N2369
That was a high-frequency part for the time, spec'd at 1200MHz...
the problem is, that it is an rf-transistor and can't be driven at
30V/0.2A, I found a complementary in an old table KTT, the 2N2894A,
but it also has max. 12V, so I find no other than the 2N3906.
An old Raytheon datasheet says the 2N2894 was doped with platinum.
[snip] |
Thanks for tracking that down, Win! Gold in a PNP was certainly
troubling my ancient remembrance of semiconductor chemistry.
...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food. |
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