Tektronix 7704A power supply question

[Joerg]

Jim Yanik wrote:

"DaveM" <masondg4499@comcast99.net> wrote in
news:KZ-dnYGRzOqFrTnUnZ2dnUVZ_tmWnZ2d@giganews.com:

"Joerg" <notthisjoergsch@removethispacbell.net> wrote in message
news:%SUol.23432$ZP4.7265@nlpi067.nbdc.sbc.com...
Robert Baer wrote:
Joerg wrote:

So, besides some other things the Tektronix 7704A had croaked.
T'was the switcher. No schematics available, the usual. Looks like
someone really "jammed it together" which is strange since this
unit has always had top-notch service at calibration places.
Anyhow, got it fixed now but there is something weird on there and
I'd like to know if it is normal:

A little neon lamp like the ones found in older illuminated light
switches flashes at sub-second intervals and the switcher does
slight ticking noises every time it flashes. The neon lamp looks
old, pretty black inside, but I dare not to swap it (don't touch a
running system ...). Other than that the whole scope works fine
again.

Is this normal? Is that neon lamp used as a "predecessor" of a
TL431?

Hmm..the schematic i have shows only 3 neons, one between the 115V
and the
230V switch terminls, one in oscillator configurationacross the
output of the FWB, and the third from the 115V switch terminal to
some ?reference? line.
In certain applications, neon bulbs were purposly burned in (for
looong
periods), turning them black inside, in order to gain voltage
stability.
I understand the technique is both an art and a science.

That's what I was afraid they did. I've seen them used as references
as well, a quite horrid method because when it fails you are up the
creek. If I had the schematic I could try to replace it with
something more durable. Did you find the 7704A schematic online
somewhere? BAMA and Bitsavers didn't have it. Only the 7704 non-A and
that's way different, mostly discrete while the 7704A has those
new-fangled Tek custom chips :-(

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.

Joerg,
You can download the complete manual set for the 7704 and 7704A scopes
from
http://www.ko4bb.com/cgi-bin/manuals.pl?dir=Tektronix/Tektronix_-_7704.
Not the best quality, but very readable.

Cheers!

you do know there's a huge difference between the 7704 and 7704A?

That's just the nice thing, these schematics are for the 7704A. Yeehaw!

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.

 

[DaveM]

"Jim Yanik" <jyanik@abuse.gov> wrote in message
news:Xns9BBCAEF41FD53jyanikkuanet@74.209.136.87...

"DaveM" <masondg4499@comcast99.net> wrote in
news:KZ-dnYGRzOqFrTnUnZ2dnUVZ_tmWnZ2d@giganews.com:

"Joerg" <notthisjoergsch@removethispacbell.net> wrote in message
news:%SUol.23432$ZP4.7265@nlpi067.nbdc.sbc.com...
Robert Baer wrote:
Joerg wrote:

So, besides some other things the Tektronix 7704A had croaked.
T'was the switcher. No schematics available, the usual. Looks like
someone really "jammed it together" which is strange since this
unit has always had top-notch service at calibration places.
Anyhow, got it fixed now but there is something weird on there and
I'd like to know if it is normal:

A little neon lamp like the ones found in older illuminated light
switches flashes at sub-second intervals and the switcher does
slight ticking noises every time it flashes. The neon lamp looks
old, pretty black inside, but I dare not to swap it (don't touch a
running system ...). Other than that the whole scope works fine
again.

Is this normal? Is that neon lamp used as a "predecessor" of a
TL431?

Hmm..the schematic i have shows only 3 neons, one between the 115V
and the
230V switch terminls, one in oscillator configurationacross the
output of the FWB, and the third from the 115V switch terminal to
some ?reference? line.
In certain applications, neon bulbs were purposly burned in (for
looong
periods), turning them black inside, in order to gain voltage
stability.
I understand the technique is both an art and a science.


That's what I was afraid they did. I've seen them used as references
as well, a quite horrid method because when it fails you are up the
creek. If I had the schematic I could try to replace it with
something more durable. Did you find the 7704A schematic online
somewhere? BAMA and Bitsavers didn't have it. Only the 7704 non-A and
that's way different, mostly discrete while the 7704A has those
new-fangled Tek custom chips :-(

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.


Joerg,
You can download the complete manual set for the 7704 and 7704A scopes
from
http://www.ko4bb.com/cgi-bin/manuals.pl?dir=Tektronix/Tektronix_-_7704.
Not the best quality, but very readable.

Cheers!

you do know there's a huge difference between the 7704 and 7704A?

--
Jim Yanik
jyanik
at
kua.net

Yes, Jim, I'm aware of the differences between the two models. I threw in that
comment because a reference to the 7704 was made in a previous post, just in
case Joerg wanted to see the schematics for both models for comparison.

--

Dave M
MasonDG44 at comcast dot net (Just substitute the appropriate characters in the
address)

Life is like a roll of toilet paper; the closer it gets to the end, the faster
it goes.

 

[legg]

On Tue, 24 Feb 2009 08:06:25 -0800, Joerg
<notthisjoergsch@removethispacbell.net> wrote:

Jim Yanik wrote:
Robert Baer <robertbaer@localnet.com> wrote in
snip
older 7704A's used to have a neon-based start circuit instead of the 32V
diac.
the ticking is the supply trying to start.


Thing is, after I fixed it the supply starts every single time. After it
starts the ticking and neon flashing continues.

One of the reasons I keep on using this scope is the incredibly sharp
CRT display. Even the venerable 2465 can't rival that. Plus it has that
ghostly blue glow in the dark after I shut down the lab, kind of cool.
Some day I am going to get me a 7L13 or so for it, just for kicks.

The self-start circuit (basically an RC discharge) should be disabled
in operation through an active drain or rectifier discharge of the 'C'
in the circuit.

RL

 

[legg]

On Tue, 24 Feb 2009 08:06:25 -0800, Joerg
<notthisjoergsch@removethispacbell.net> wrote:

Jim Yanik wrote:

older 7704A's used to have a neon-based start circuit instead of the 32V
diac.
the ticking is the supply trying to start.


Thing is, after I fixed it the supply starts every single time. After it
starts the ticking and neon flashing continues.

CR3046 or cr3050 are supposed to keep C3048 discharged when the unit

is running.

RL

 

[Robert Baer]

Joerg wrote:

ehsjr wrote:

Joerg wrote:

So, besides some other things the Tektronix 7704A had croaked. T'was
the switcher. No schematics available, the usual. Looks like someone
really "jammed it together" which is strange since this unit has
always had top-notch service at calibration places. Anyhow, got it
fixed now but there is something weird on there and I'd like to know
if it is normal:

A little neon lamp like the ones found in older illuminated light
switches flashes at sub-second intervals and the switcher does slight
ticking noises every time it flashes. The neon lamp looks old, pretty
black inside, but I dare not to swap it (don't touch a running system
...). Other than that the whole scope works fine again.

Is this normal? Is that neon lamp used as a "predecessor" of a TL431?


Manuals (free) for 7704 & 7704A can are here:
http://bama.sbc.edu/tektroni.htm


That now wants a user name and password :-(

Anyhow, I've seen the manuals. Problem is, there is only a manual with
schematics for the 7704 which is hugely different from the 7704A. Tek
made a lot of customs chips for that, of course now all pretty much
unobtanium.


These guys can answer your TEK question:
http://tech.groups.yahoo.com/group/TekScopes/


Thanks, I'll try that.

Hmmm..my manual is titled 7704A.

Useful?

 

[JW]

On Tue, 24 Feb 2009 08:37:22 -0800 Joerg
<notthisjoergsch@removethispacbell.net> wrote in Message id:
<8nVol.23450$ZP4.7784@nlpi067.nbdc.sbc.com>:

Edward Knobloch wrote:


Manuals (free) for 7704 & 7704A can are here:
http://bama.sbc.edu/tektroni.htm


That now wants a user name and password :-(


BAMA (the Boat anchor Manual source) prompts for a username/password
if there are too many users on at a time.
Unfortunately with BAMA, that is most of the time.

Here is the mirror for BAMA, which has the same manuals
available, with a more robust data pipeline:
http://bama.edebris.com/manuals/tek/


Thanks, Ed, I've bookmarked it. Unfortunately (for me) this site like
the others only has the user manual for the 7704A. No schematics :-(

Hi Joerg,

Service manual for the 7704A is here:
http://www.ko4bb.com/cgi-bin/manuals.pl
2 files about 25MB each, so I didn't see if the schematics were in them.
Good luck.

 

[Joerg]

Robert Baer wrote:

Joerg wrote:
ehsjr wrote:

Joerg wrote:

So, besides some other things the Tektronix 7704A had croaked. T'was
the switcher. No schematics available, the usual. Looks like someone
really "jammed it together" which is strange since this unit has
always had top-notch service at calibration places. Anyhow, got it
fixed now but there is something weird on there and I'd like to know
if it is normal:

A little neon lamp like the ones found in older illuminated light
switches flashes at sub-second intervals and the switcher does
slight ticking noises every time it flashes. The neon lamp looks
old, pretty black inside, but I dare not to swap it (don't touch a
running system ...). Other than that the whole scope works fine again.

Is this normal? Is that neon lamp used as a "predecessor" of a TL431?


Manuals (free) for 7704 & 7704A can are here:
http://bama.sbc.edu/tektroni.htm


That now wants a user name and password :-(

Anyhow, I've seen the manuals. Problem is, there is only a manual with
schematics for the 7704 which is hugely different from the 7704A. Tek
made a lot of customs chips for that, of course now all pretty much
unobtanium.


These guys can answer your TEK question:
http://tech.groups.yahoo.com/group/TekScopes/


Thanks, I'll try that.

Hmmm..my manual is titled 7704A.
Useful?

Thanks. Dave pointed me to the link where I could get it. Confirmed the
suspicion that the neon bulb is just there to warn of high voltages.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.

 

[Joerg]

legg wrote:

On Tue, 24 Feb 2009 08:06:25 -0800, Joerg
notthisjoergsch@removethispacbell.net> wrote:

Jim Yanik wrote:

older 7704A's used to have a neon-based start circuit instead of the 32V
diac.
the ticking is the supply trying to start.

Thing is, after I fixed it the supply starts every single time. After it
starts the ticking and neon flashing continues.

CR3046 or cr3050 are supposed to keep C3048 discharged when the unit
is running.

Luckily it doesn't have a neon bulb in place of CR3040 like some older
machines. If it acts up again I'll probe around that area but so far the
scope purring alone just fine.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.

 

[Joerg]

Tony Miklos wrote:

Joerg wrote:
So, besides some other things the Tektronix 7704A had croaked. T'was
the switcher. No schematics available, the usual. Looks like someone
really "jammed it together" which is strange since this unit has
always had top-notch service at calibration places. Anyhow, got it
fixed now but there is something weird on there and I'd like to know
if it is normal:

A little neon lamp like the ones found in older illuminated light
switches flashes at sub-second intervals and the switcher does slight
ticking noises every time it flashes. The neon lamp looks old, pretty
black inside, but I dare not to swap it (don't touch a running system
...). Other than that the whole scope works fine again.

Is this normal? Is that neon lamp used as a "predecessor" of a TL431?

Sounds odd that it has that symptom and still works. I used to repair a
lot of switching P/S's and the ticking is a common symptom. 99% of the
time they have bad caps. When testing and/or replacing caps in the
switcher, be sure to test them for low ESR. This is a must. As far as
the neon lamp, I've often seen them used for over voltage protection.

According to the schematic it's just a signal lamp in an oscillator
setting (R, C, neon lamp), to warn of remaining charge in the big
primary 'lytics. So there is no connection between this and anything
that can tick. But tick it does, exactly in rhythm with the neon lamp.
Oh well.

When I removed this power supply it was in a sorry state. The circuit
board was truly jammed in, the two big caps bent and pressed against the
aluminum panel with the large round holes instead of resting inside the
holes. The FR-4 also bent with the plastic standoff dangling in the air.
Oh man. Now it sits there like it should.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.

 

[Fred Abse]

On Mon, 23 Feb 2009 16:43:57 -0800, Joerg wrote:

So, besides some other things the Tektronix 7704A had croaked. T'was the
switcher. No schematics available, the usual. Looks like someone really
"jammed it together" which is strange since this unit has always had
top-notch service at calibration places.

I admire your faith. I've seen some horrendous "workmanship" hidden behind
cal seals.

Anyhow, got it fixed now but
there is something weird on there and I'd like to know if it is normal:

A little neon lamp like the ones found in older illuminated light
switches flashes at sub-second intervals and the switcher does slight
ticking noises every time it flashes. The neon lamp looks old, pretty
black inside, but I dare not to swap it (don't touch a running system
...). Other than that the whole scope works fine again.

Is this normal? Is that neon lamp used as a "predecessor" of a TL431?

The neon is really a little relaxation oscillator to indicate that the
high-voltage reservoir capacitors are charged.

It isn't really a switcher in the strict sense of the word. It's actually
sort-of-sinewave, resonant around 20kHz. If it ticks, that's usually a
sign that it's going into current limiting, or could be under-loaded. They
need about 40 watts of load spread around the rails to work properly. The
control chip actually gets its Vcc supply from the current feedback
(dunnask me why), so it won't work at all on insufficient load, and will
repeatedly trigger its startup circuit which uses a sort of diac thingy.

Try Manuals Plus (www.manualsplus.com) for the manual.They have the
service manual in stock for 65 bucks. You really do need it. The 7704A and
7704 are *different*, especially around the PSU The 7704 has the CRT HV
supply integrated into the main PSU, the 7704A has a separate HV unit
"upstairs" in the removable display section, driven from the main PSU up
two coaxial cables.

A lot of apparent PSU problems involving ticking turn out to be shorted
capacitors, especially tantalums, usually on the interface PCB, where
they're a bitch to get at ;-(

--
"Electricity is of two kinds, positive and negative. The difference
is, I presume, that one comes a little more expensive, but is more
durable; the other is a cheaper thing, but the moths get into it."
(Stephen Leacock)

 

[Joerg]

Fred Abse wrote:

On Mon, 23 Feb 2009 16:43:57 -0800, Joerg wrote:

So, besides some other things the Tektronix 7704A had croaked. T'was the
switcher. No schematics available, the usual. Looks like someone really
"jammed it together" which is strange since this unit has always had
top-notch service at calibration places.

I admire your faith. I've seen some horrendous "workmanship" hidden behind
cal seals.

Like some oil change places? I always do that myself. Same for lab gear
maintenance, where I give the units extra TLC. EPROM re-seating and such.

Anyhow, got it fixed now but
there is something weird on there and I'd like to know if it is normal:

A little neon lamp like the ones found in older illuminated light
switches flashes at sub-second intervals and the switcher does slight
ticking noises every time it flashes. The neon lamp looks old, pretty
black inside, but I dare not to swap it (don't touch a running system
...). Other than that the whole scope works fine again.

Is this normal? Is that neon lamp used as a "predecessor" of a TL431?

The neon is really a little relaxation oscillator to indicate that the
high-voltage reservoir capacitors are charged.

It isn't really a switcher in the strict sense of the word. It's actually
sort-of-sinewave, resonant around 20kHz. If it ticks, that's usually a
sign that it's going into current limiting, or could be under-loaded. They
need about 40 watts of load spread around the rails to work properly. The
control chip actually gets its Vcc supply from the current feedback
(dunnask me why), so it won't work at all on insufficient load, and will
repeatedly trigger its startup circuit which uses a sort of diac thingy.

Must be a bit higher than 20kHz, else the shepherd would leave the lab
and give me "the looks". She always does that when one of my switcher
test beds goes into hiccup mode.

Try Manuals Plus (www.manualsplus.com) for the manual.They have the
service manual in stock for 65 bucks. You really do need it. The 7704A and
7704 are *different*, especially around the PSU The 7704 has the CRT HV
supply integrated into the main PSU, the 7704A has a separate HV unit
"upstairs" in the removable display section, driven from the main PSU up
two coaxial cables.

A lot of apparent PSU problems involving ticking turn out to be shorted
capacitors, especially tantalums, usually on the interface PCB, where
they're a bitch to get at ;-(

Thanks to Dave M I now have the schematics. Luckily there seem to be not
tantalums so I'll just keep using the scope until something happens.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.

 

[legg]

On Fri, 27 Feb 2009 16:34:24 -0800, Joerg
<notthisjoergsch@removethispacbell.net> wrote:

Tony Miklos wrote:
Joerg wrote:
So, besides some other things the Tektronix 7704A had croaked. T'was
the switcher. No schematics available, the usual. Looks like someone
really "jammed it together" which is strange since this unit has
always had top-notch service at calibration places. Anyhow, got it
fixed now but there is something weird on there and I'd like to know
if it is normal:

A little neon lamp like the ones found in older illuminated light
switches flashes at sub-second intervals and the switcher does slight
ticking noises every time it flashes. The neon lamp looks old, pretty
black inside, but I dare not to swap it (don't touch a running system
...). Other than that the whole scope works fine again.

Is this normal? Is that neon lamp used as a "predecessor" of a TL431?

Sounds odd that it has that symptom and still works. I used to repair a
lot of switching P/S's and the ticking is a common symptom. 99% of the
time they have bad caps. When testing and/or replacing caps in the
switcher, be sure to test them for low ESR. This is a must. As far as
the neon lamp, I've often seen them used for over voltage protection.


According to the schematic it's just a signal lamp in an oscillator
setting (R, C, neon lamp), to warn of remaining charge in the big
primary 'lytics. So there is no connection between this and anything
that can tick. But tick it does, exactly in rhythm with the neon lamp.
Oh well.

When I removed this power supply it was in a sorry state. The circuit
board was truly jammed in, the two big caps bent and pressed against the
aluminum panel with the large round holes instead of resting inside the
holes. The FR-4 also bent with the plastic standoff dangling in the air.
Oh man. Now it sits there like it should.

The flashing of DS3019 should not produce audible effects. The firing
of diac CR3040 to discharge C3048 will.

RL

 

[Joerg]

legg wrote:

On Fri, 27 Feb 2009 16:34:24 -0800, Joerg
notthisjoergsch@removethispacbell.net> wrote:

Tony Miklos wrote:
Joerg wrote:
So, besides some other things the Tektronix 7704A had croaked. T'was
the switcher. No schematics available, the usual. Looks like someone
really "jammed it together" which is strange since this unit has
always had top-notch service at calibration places. Anyhow, got it
fixed now but there is something weird on there and I'd like to know
if it is normal:

A little neon lamp like the ones found in older illuminated light
switches flashes at sub-second intervals and the switcher does slight
ticking noises every time it flashes. The neon lamp looks old, pretty
black inside, but I dare not to swap it (don't touch a running system
...). Other than that the whole scope works fine again.

Is this normal? Is that neon lamp used as a "predecessor" of a TL431?
Sounds odd that it has that symptom and still works. I used to repair a
lot of switching P/S's and the ticking is a common symptom. 99% of the
time they have bad caps. When testing and/or replacing caps in the
switcher, be sure to test them for low ESR. This is a must. As far as
the neon lamp, I've often seen them used for over voltage protection.

According to the schematic it's just a signal lamp in an oscillator
setting (R, C, neon lamp), to warn of remaining charge in the big
primary 'lytics. So there is no connection between this and anything
that can tick. But tick it does, exactly in rhythm with the neon lamp.
Oh well.

When I removed this power supply it was in a sorry state. The circuit
board was truly jammed in, the two big caps bent and pressed against the
aluminum panel with the large round holes instead of resting inside the
holes. The FR-4 also bent with the plastic standoff dangling in the air.
Oh man. Now it sits there like it should.

The flashing of DS3019 should not produce audible effects. The firing
of diac CR3040 to discharge C3048 will.

Maybe the neon lamp and the diac have caucused into some kind of
collective bargaining process ;-)

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.

 

[Fred Abse]

On Sun, 01 Mar 2009 15:24:52 -0800, Joerg wrote:

Must be a bit higher than 20kHz, else the shepherd would leave the lab
and give me "the looks". She always does that when one of my switcher
test beds goes into hiccup mode.

I could do with a lab-trained dog. I'm down to about 12kHz, now. In my
teens I could hear 24.

Just dug the 7704A service manual out. That says 25kHz. In the past, I've
tested the transformers out of circuit by resonating the primary. Using
the series capacitor from the PSU, if memory serves, driving with 20
volts, I got around 30kHz with a Q of about 16. Can't find my notes any
more.

--
"Electricity is of two kinds, positive and negative. The difference
is, I presume, that one comes a little more expensive, but is more
durable; the other is a cheaper thing, but the moths get into it."
(Stephen Leacock)

 

[Jim Thompson]

On Mon, 02 Mar 2009 14:52:36 -0800, Fred Abse
<excretatauris@invalid.invalid> wrote:

On Sun, 01 Mar 2009 15:24:52 -0800, Joerg wrote:

Must be a bit higher than 20kHz, else the shepherd would leave the lab
and give me "the looks". She always does that when one of my switcher
test beds goes into hiccup mode.

I could do with a lab-trained dog. I'm down to about 12kHz, now. In my
teens I could hear 24.

I'm down to can't hear the wife unless she's right in my face ;-)

(Almost totally deaf in the left ear... you know... the one I damaged
while designing a hearing aid chip ;-)

Just dug the 7704A service manual out. That says 25kHz. In the past, I've
tested the transformers out of circuit by resonating the primary. Using
the series capacitor from the PSU, if memory serves, driving with 20
volts, I got around 30kHz with a Q of about 16. Can't find my notes any
more.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine Sometimes I even put it in the food

 

[Joerg]

Fred Abse wrote:

On Sun, 01 Mar 2009 15:24:52 -0800, Joerg wrote:

Must be a bit higher than 20kHz, else the shepherd would leave the lab
and give me "the looks". She always does that when one of my switcher
test beds goes into hiccup mode.

I could do with a lab-trained dog. I'm down to about 12kHz, now. In my
teens I could hear 24.

I can only hear that high stuff on one ear, the other one always kind of
rings a bit, courtesy of a kablouie event while in the army. Well, at
least it missed us by about 10 feet.

Just dug the 7704A service manual out. That says 25kHz. In the past, I've
tested the transformers out of circuit by resonating the primary. Using
the series capacitor from the PSU, if memory serves, driving with 20
volts, I got around 30kHz with a Q of about 16. Can't find my notes any
more.

Just looked in the schematic. The waveforms are lighter colored, hard to
read, but for both REG OUT and MONO RAMP on U3105 (the Tektronix custpm
PWM chip) it says 20usec which would be 50kHz.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.

 

[krw]

In article <CCZql.20901$yr3.17310@nlpi068.nbdc.sbc.com>,
notthisjoergsch@removethispacbell.net says...>

Fred Abse wrote:
On Sun, 01 Mar 2009 15:24:52 -0800, Joerg wrote:

Must be a bit higher than 20kHz, else the shepherd would leave the lab
and give me "the looks". She always does that when one of my switcher
test beds goes into hiccup mode.

I could do with a lab-trained dog. I'm down to about 12kHz, now. In my
teens I could hear 24.

One of my cow-orkers in college could hear somewhat above 30kHz. I
used to drive him crazy with Waveteks. ;-)

I can only hear that high stuff on one ear, the other one always kind of
rings a bit, courtesy of a kablouie event while in the army. Well, at
least it missed us by about 10 feet.

At least you heard that one.

<snip>

 

[Joerg]

krw wrote:

In article <CCZql.20901$yr3.17310@nlpi068.nbdc.sbc.com>,
notthisjoergsch@removethispacbell.net says...
Fred Abse wrote:
On Sun, 01 Mar 2009 15:24:52 -0800, Joerg wrote:

Must be a bit higher than 20kHz, else the shepherd would leave the lab
and give me "the looks". She always does that when one of my switcher
test beds goes into hiccup mode.
I could do with a lab-trained dog. I'm down to about 12kHz, now. In my
teens I could hear 24.


One of my cow-orkers in college could hear somewhat above 30kHz. I
used to drive him crazy with Waveteks. ;-)

I can only hear that high stuff on one ear, the other one always kind of
rings a bit, courtesy of a kablouie event while in the army. Well, at
least it missed us by about 10 feet.

At least you heard that one.

The sergeant heard it first. Ouieeeee ... sound did not change ... "Oh
S..t! Down!" ... *BOOM* ... splat

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.

 

[krw]

In article <S6_ql.2798$Lr6.1296@flpi143.ffdc.sbc.com>,
notthisjoergsch@removethispacbell.net says...>

krw wrote:
In article <CCZql.20901$yr3.17310@nlpi068.nbdc.sbc.com>,
notthisjoergsch@removethispacbell.net says...
Fred Abse wrote:
On Sun, 01 Mar 2009 15:24:52 -0800, Joerg wrote:

Must be a bit higher than 20kHz, else the shepherd would leave the lab
and give me "the looks". She always does that when one of my switcher
test beds goes into hiccup mode.
I could do with a lab-trained dog. I'm down to about 12kHz, now. In my
teens I could hear 24.


One of my cow-orkers in college could hear somewhat above 30kHz. I
used to drive him crazy with Waveteks. ;-)

I can only hear that high stuff on one ear, the other one always kind of
rings a bit, courtesy of a kablouie event while in the army. Well, at
least it missed us by about 10 feet.

At least you heard that one.


The sergeant heard it first. Ouieeeee ... sound did not change ... "Oh
S..t! Down!" ... *BOOM* ... splat

Subsonic? Where was this?

 

[Joerg]

krw wrote:

In article <S6_ql.2798$Lr6.1296@flpi143.ffdc.sbc.com>,
notthisjoergsch@removethispacbell.net says...
krw wrote:
In article <CCZql.20901$yr3.17310@nlpi068.nbdc.sbc.com>,
notthisjoergsch@removethispacbell.net says...
Fred Abse wrote:
On Sun, 01 Mar 2009 15:24:52 -0800, Joerg wrote:

Must be a bit higher than 20kHz, else the shepherd would leave the lab
and give me "the looks". She always does that when one of my switcher
test beds goes into hiccup mode.
I could do with a lab-trained dog. I'm down to about 12kHz, now. In my
teens I could hear 24.

One of my cow-orkers in college could hear somewhat above 30kHz. I
used to drive him crazy with Waveteks. ;-)

I can only hear that high stuff on one ear, the other one always kind of
rings a bit, courtesy of a kablouie event while in the army. Well, at
least it missed us by about 10 feet.
At least you heard that one.

The sergeant heard it first. Ouieeeee ... sound did not change ... "Oh
S..t! Down!" ... *BOOM* ... splat

Subsonic? Where was this?

It was during exercises. One group was training heavy-ammo tank attacks
and for some reason one went way in the wrong direction and towards us.
It made a crater. Problem was, the doc was too young to recognize that
you must send soldiers to the hospital right away for a constant blood
thinner IV, he sent me back to the barracks for the weekend. Monday he
became quite worried and sent me to an army hospital but by then the
chances to fully recover the hearing had dropped to 20% or so :-(

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.