Mosquito Sound

[Ron Cook]

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joe wrote:

Hi

i have a notebook that uses a Ac adapter with output 19v 4.74A
(=90watt).
I would like to use my notebook in my car, so i need an DC adapter.
I saw on ebay universal dc adapter. but the output is only 19v-3.5A or
19v-4A. My question is, could i use these adapter since the result in
watt would only be around 76 watt max ?
Thanks
Joe

I would not use the lower-power adapter.
Although the adapter *might* operate the laptop with no apparent problems,
you're going to be running the adapter past its rated amperage.

This could result in failure of the adapter, overheating which could result
in a fire if the unit is on a combustible surface, or just a spark and a
puff of really evil-smelling smoke which could take days to remove.

If the adapter also inverts the output and it fails in such a manner that it
connects the battery source directly to the laptop (short-circuit), you
could lose the laptop.

But wait! I have some good news; I just saved a bunch... ...

You might, on the gripping hand, want to consider a small *regulated*
DC-to-AC inverter for the laptop.
This will plug into a 12-volt source in the car (cigarette lighter socket,
for example) and provide a goodquality AC output at a nominal 117 volts.
Your laptop's correct adapter would then be powered from this.

These are available for about US $40 to $150 in most of the better
electronics and department stores.

- --
Ron n1zhi
roncook@verizon.net
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[john]

Corrupt Micro or bad Eprom..

kip


--
"Watch the return E-Mail addy its false"
"Im anonymous" <acctforjunk@yahoo.com> wrote in message
news:bffabe31.0407080843.52e822b3@posting.google.com...

I have an AC/DC Magnavox TV, model RK3955 AL02, manufactured Nov.
1989. It has a remote and pushbutton up/down volume with on screen
display.

Even with the volume all the way to minimum, it's still quite loud.
If I increase volume, it gets louder as expected. However, right at
the mid point, it gets quieter, then increases again all the way to
max. What could be causing this?

 

[Hugh Prescott]

See the tekscope group at yahoo.com

There have been several threads on this problem and there appears to be no
repair.

Hugh



"Jeffrey Dutky" <dutky@bellatlantic.net> wrote in message
news:f6013729.0407081023.2a7a841b@posting.google.com...

I keep seeing messages about the Tek 24xx faulty horizontal output
chips. Now, I don't actually HAVE a 2445 or 2465 (much less, one
suffering from a faulty U800 chip) but I'm very curious. The
descriptions of the chip and the effects of its failure suggest that
U800 is some kind of high frequency amplifier. Wouldn't it be possible
to rig a replacement for the chip from discrete components? What are
the specifications for the chip?

- Jeff Dutky

 

[Jim Yanik]

dutky@bellatlantic.net (Jeffrey Dutky) wrote in
news:f6013729.0407081023.2a7a841b@posting.google.com:

I keep seeing messages about the Tek 24xx faulty horizontal output
chips. Now, I don't actually HAVE a 2445 or 2465 (much less, one
suffering from a faulty U800 chip) but I'm very curious. The
descriptions of the chip and the effects of its failure suggest that
U800 is some kind of high frequency amplifier. Wouldn't it be possible
to rig a replacement for the chip from discrete components? What are
the specifications for the chip?

- Jeff Dutky

TEK no longer knows what the specs are,their IC/hybrid manufacturing unit
was sold to Maxim long ago,who then forced a last-time buy and ceased
production of TEK-made ICs(155 and 234 prefix ICs).That's what terminated
the 2400 product line.I doubt you could get Maxim to release the specs.
TEK will have nothing to do with these scopes.

This H-output amp is a differential output amp with high linearity and very
high freq response(to display a <100PS/div sweep,IIRC),designed to directly
drive a CRT's plate capacitance with a specific deflection sensitivity,and
it also has programmable gains,and IIRC,switches in the readout signal and
external horizontal inputs.It's not a simple IC, but a combo analog/digital
IC.

Bottom line is that there is not enough product base to cost-effectively
support a reverse engineering effort.

BTW,this has been discussed in this NG (or sci.electronic.design) before.


--
Jim Yanik
jyanik-at-kua.net

 

[Ed Price]

"Andrew Tweddle" <sarason@alphalink.com.au> wrote in message
news:40eb786a@news.alphalink.com.au...

Andrew wrote:
I've just bought a HP8560A spectrum analyser (sorry for UK spelling).
The front panel tells me it is a 8560A. When it first turns on it
writes 8560E to the screen, also in CONFIG / DATECODE & OPTIONS it
lists 8560E and 002 (002 is the tracking generator).

It seems to have the features of the 8560E, 1Hz RBW and fancy power
measurement options.

I've searched the web but cannot find out the scope of this upgrade.
Can anyone please enlighten me more? Has the spec of a 8560E or is it
some in-between animal.

Andrew
When I win $1million dollars in a lottery, I sure won't be looking a
gift horse in the mouth!

Andrew

The 856x series analyzers had plug-in ROM sets to allow for firmware
upgrades. I have an early 8562A (1987), and I found that HP had a new ROM
set that included things like FFT functions, etc. The I found that there
were 4 and 5 ROM chip sets. After I ordered and installed the right chip
set, I found that my machine complained of several internal faults on
power-up. I got tired of playing around, and put the original ROMs back in.

Who knows what somebody may have plugged into your 8560A; just be happy it
works!

Ed
wb6wsn

 

[Watson A.Name - \"Watt Su]

"BlackWater" <bw@barrk.net> wrote in message
news:gsbab0del6usif52le576rl8vnumkppgg3@4ax.com...

I need to run several ethernet lines along the outside of
buildings - in a lightning-prone area. Tried this once
before and got smoking ruin as a reward. What's needed
are some kind of converters that will plug right into
an ordinary 10/100 ethernet hub, convert the signal to
optical that can be sent a hundred meters or so on
economical/easy PLASTIC fiber, and then convert back
to an ordinary 10/100 TX at the target PC or hub.

Has anyone come across anything like these devices ?

First off you should post this to comp.dcom.cabling.

No. Plastic fiber isn't good enough for 100Mb. Buy a pair of media
converters and a hundred M of multimode cable with the ends
pre-terminaterd with the proper connectors. Companies will make custom
lenghts for you. Milan AKA Digi make media converters.

> Reply to group.

 

[Watson A.Name - \"Watt Su]

<sales@semiautosten.com> wrote in message
news:968bc62e.0405161615.554187f7@posting.google.com...

A TON of US Govt Surplus Electronic Test Equipment Available for
fraction of cost. See all at the link below. Copy and paste. Free
shipping on all within contiguous US.

We don't mind hobbyists posting an occasional ad here, but it's
extremely rude for commercial companies to use this discussion group for
advertising.

> http://www.xxxxxxxxxxxxx.com/kits/electronics/avail.html

 

[Lou]

When I went to that site when first posted, ALL I seen, was "a" page of gear
for sale. What "I" seen, had no prices that I can recall and it certainly
didn't show any way to get in touch with anyone if interested. It didn't
even have links to a home page or other pages of equipment. Maybe the link
was bad, I don't know but that is how it reacted when I looked at it. Maybe
someone else would have better luck.

Lou

"Watson A.Name - "Watt Sun, the Dark Remover"" <NOSPAM@dslextreme.com> wrote
in message news:10evavr3n5v2p24@corp.supernews.com...

sales@semiautosten.com> wrote in message
news:968bc62e.0405161615.554187f7@posting.google.com...
A TON of US Govt Surplus Electronic Test Equipment Available for
fraction of cost. See all at the link below. Copy and paste. Free
shipping on all within contiguous US.

We don't mind hobbyists posting an occasional ad here, but it's
extremely rude for commercial companies to use this discussion group for
advertising.

http://www.xxxxxxxxxxxxx.com/kits/electronics/avail.html

 

[Watson A.Name - \"Watt Su]

"Walter Alter" <neuronjockey@nospamearthlink.net> wrote in message
news:ReQuc.17102$Tn6.6834@newsread1.news.pas.earthlink.net...

Anyone know of a schematic or plans that might be engineered to serve
as an
IR treatement device for nerve problems associated with diabetes?
Commercial units go for $2-3,000 and my local MIRE (monochromatic
infrared
energy) clinic is overbooked. The device is basically an array of 80
or so
820nm diodes mounted on a flexible cloth rectangle that is placed in
contact
with the affected area, usually the feet for 20 minutes or so. The
lights
are pulsed, tho the rate of pulsing is not a matter of therapy, but
has to
do with the duty cycle rating of the LED.

It would be a snap for an electronics wiz to throw one of these
together and
I'd give it a try if I had a schematic and some assembly tips. For
example,
I don't know if surface mount LED's would be the easiest to work with,
battery power source vs 110, etc. Any help on this would be greatly
appreciated. MIRE units are becoming a standard effective
self-administered
therapy for diabetics who develop nerve pain and anasthesia in their
feet,
and if a workable kit approach could be put out there, thousands of
folks
could be helped that otherwise couldn't afford it.

Medical devices have to be gov't approved. Thousands of victims could
be hurt by a medical device gone bad. So buy a commercial one. The
extra money you pay protects your life.

And also, selling a kit might be illegal.

Many thanks,
Walter

 

[Watson A.Name - \"Watt Su]

"John Marsh" <jmarsh1000@hotmail.com> wrote in message
news:18f0c9bf.0405260229.20c67492@posting.google.com...

Hi everyone,
I have an ancient Heathkit 10-12U oscilloscope,full of valves (tubes)
and great for airing laundry. It seems to be only AC coupled; i.e.
connecting a steady DC source produces a brief jump of the trace. If I
connect a source of pulsed DC which peaks at 9V, how do I interpret &
calibrate the trace? Pulse generator is a 555 timer as astable.
Viva valves,
John.

You adjust the calibrate (if it has one) until the trace has 9 vertical
divisions on the graticule (if it has one).

 

[Watson A.Name - \"Watt Su]

"Asa Cannell" <acannell@wwc.com> wrote in message
news:51ca721c.0406191506.5c7d313b@posting.google.com...

I've recently done an extensive web search for the ultimate
multimeter. Ideally it would have at least the following features:

-inductance, capacitance, resistance
-frequency
-voltage (ac/dc, truerms)
-current (ac/dc)
-relative mode
-temperature
-autoranging for all measurements
-continuity
-backlight
-10000 counts (or better)
-less than $200

The wavetek meterman 37xr (www.metermantesttools.com) meets all of the
criteria except it doesnt measure temperature. But I WANT temperature
(why dont they just throw it in?). It seems that there are many meters
that almost meet the criteria, except they dont measure inductance.

Does anyone know of a meter that has everything?

I just love it when someone expects everything and doesn't want to pay
for it. Raise your max price until you get what you want. Duh.


> Asa

 

[Watson A.Name - \"Watt Su]

"John Miles" <jmiles@pop.removethistomailme.net> wrote in message
news:MPG.1b3e74e82f248a829896c8@news-central.giganews.com...

In article <51ca721c.0406191506.5c7d313b@posting.google.com>,
acannell@wwc.com says...

The wavetek meterman 37xr (www.metermantesttools.com) meets all of
the
criteria except it doesnt measure temperature. But I WANT
temperature
(why dont they just throw it in?). It seems that there are many
meters
that almost meet the criteria, except they dont measure inductance.

Does anyone know of a meter that has everything?

Nope, including that one. Its capacitance- and inductance-measuring
precision are both literally 1,000 times worse than an inexpensive
dedicated LC meter (http://www.aade.com) can offer, and 40 nF/4 mH
minimum ranges aren't useful for anyone except maybe an HVAC
repairman.

This is just an example of a product that does a great many things
badly.

Typical Wavetek. I have the AADE LC meter IIb, and I'm very satisfied
with it. The only thing I wished it had was a power jack for an AC
adapter. But I took care of that.. ;-)

For temperature measurement, you can buy a thermocouple adapter (e.g.,
http://bkprecision.com/www/np_searchmodel7.asp?
lf=DMM+Temperature+Adapter) that will work with any DMM.

-- jm

------------------------------------------------------
http://www.qsl.net/ke5fx
Note: My E-mail address has been altered to avoid spam
------------------------------------------------------

 

[Ed Price]

"Watson A.Name - "Watt Sun, the Dark Remover"" <NOSPAM@dslextreme.com> wrote
in message news:10evejmgjgvhua0@corp.supernews.com...

"Asa Cannell" <acannell@wwc.com> wrote in message
news:51ca721c.0406191506.5c7d313b@posting.google.com...
I've recently done an extensive web search for the ultimate
multimeter. Ideally it would have at least the following features:

-inductance, capacitance, resistance
-frequency
-voltage (ac/dc, truerms)
-current (ac/dc)
-relative mode
-temperature
-autoranging for all measurements
-continuity
-backlight
-10000 counts (or better)
-less than $200

The wavetek meterman 37xr (www.metermantesttools.com) meets all of the
criteria except it doesnt measure temperature. But I WANT temperature
(why dont they just throw it in?). It seems that there are many meters
that almost meet the criteria, except they dont measure inductance.

Does anyone know of a meter that has everything?

I just love it when someone expects everything and doesn't want to pay
for it. Raise your max price until you get what you want. Duh.


Asa

I used to have a Fluke DMM that had a nice function; you could turn on a
continuous tone that was frequency proportional to a full-range indication.
It was really handy to be able to just listen to the tone when I was
adjusting some peak or null condition, and I often used it to test ground
bonds on airframes. Sure was handy to be able to grab and shake some big
turbine mount while listening for erratic bond conditions.

Ed
wb6wsn

 

[Jeff Wisnia]

CJT wrote:

Jeff Wisnia wrote:

My last kid, now 17 years old, just finished building himself a three
speaker subwoofer enclosure and is driving it with a Kenwood Class D
monaural amp, specifically this one:

http://incolor.inebraska.com/weisinator/components/amplifiers/kenwood/kac-8151d.htm


Another retired EE and I got to wondering what the circuit topology of
that amp is likely to be. While I could probably still draw the
schematic of a Dynaco Mk II or a McIntosh C60 (tube) amp from memory,
I sure haven't kept up with high power audio amplifier technology
since the late 60s. <G

We understand what Class D operation is, but wonder what system they
use to raise the amp's output voltage to reach the claimed power
levels into those specified speaker impedances.

The specs mention a "Copper-Shielded EE Core Transformer", If that's
not just part of the LC low pass filter after the Class-D stage, could
it possibly be a simple audio output xformer right before the speaker
terminals (Unlikely, as it'd be HUGE at those powers and low
frequencies.) Or, is it part of a dc-dc converter ahead of the Class D
switching? Maybe it's used to step up the chopped signal voltage
*between* the Class-D stage and the LC filter?

Also, do those "non peak" power levels specified by "name"
manufacturers like Kenwood really define continuous survivable rms
output power levels, or is there some industry developed standard for
typical musical "duty cycles" which isn't meantioned?

Inquiring minds want to know.

Thanks guys,


FWIW, that 40 amp fuse suggests to me that the continuous power is quite
a bit lower than 1000 watts.

Agreed, the instruction booklet which came with that amp says that's

"peak" power.

I didn't read far enough down the spec sheet it clearly reads "Power
MOSFET Switching Power Supply" which pretty much answers my question.<G>

Jeff

--
Jeff Wisnia (W1BSV + Brass Rat '57 EE)

"My luck is so bad that if I bought a cemetery, people would stop dying."

 

[Winfield Hill]

DJ wrote...

I am stuck with this problem of a BGA chip getting fried within a
few seconds of powerup. ... The CMOS chip works for a few seconds
but goes on getting hot till the swelling appears ...

Sounds like SCR latchup, wihch once triggered causes a high-current
capable turned-on SCR to appear across the supply rails. If you are
sequencing the power supplies correctly, then you may have an input
that exceeds one of the supplies and is injecting enough current
through the chip's static-protection diodes to initiate SCR latchup.

Thanks,
- Win

(email: use hill_at_rowland-dot-org for now)

 

[clive]

Is the chip 5 volt tolerant on PCI bus or are you using a 3.3V PCI
(relatively rare). Was chip definitely working?

Clive
"DJ" <deepakjnath@rediffmail.com> wrote in message
news:92f2a1e7.0407140348.11b7629c@posting.google.com...

Hi all,
I am stuck with this problem of a BGA chip getting fried within a
few seconds of powerup.The chip takes in 2 power supplies.1v for core
and a 3v3 for i/o's.There are no overshoots or undershoots that i can
see in the oscilloscopes.
The chip has worked on the same board for sometime but eventually gets
burned out or swelling in the package is seen.I have done the power
sequenceing as per the manufactures requirement but still having major
problems.
I have exhausted all the options i can look into......please help me
start looking for some thing that can lead me to the problem.
Can someone tell me where the likly problem can be?.
The CMOS chip works for a few seconds but goes on getting hot till
the swelling appears and then the chip is dead.It has a plastic
package.The chip has a PCI interface.will the overshoot on the signals
damage the chip so badly?


Regards
DJ

 

[John Larkin]

On 14 Jul 2004 04:48:08 -0700, deepakjnath@rediffmail.com (DJ) wrote:

Hi all,
I am stuck with this problem of a BGA chip getting fried within a
few seconds of powerup.The chip takes in 2 power supplies.1v for core
and a 3v3 for i/o's.There are no overshoots or undershoots that i can
see in the oscilloscopes.
The chip has worked on the same board for sometime but eventually gets
burned out or swelling in the package is seen.I have done the power
sequenceing as per the manufactures requirement but still having major
problems.
I have exhausted all the options i can look into......please help me
start looking for some thing that can lead me to the problem.
Can someone tell me where the likly problem can be?.
The CMOS chip works for a few seconds but goes on getting hot till
the swelling appears and then the chip is dead.It has a plastic
package.The chip has a PCI interface.will the overshoot on the signals
damage the chip so badly?


Regards
DJ

If it's a ram-based FPGA, it could be a weird configuration file. It's
possible to program some of these parts to self-destruct.

Could the PCI bus be pulling the i/o's above 3.3?

John

 

[CWatters]

"DJ" <deepakjnath@rediffmail.com> wrote in message
news:92f2a1e7.0407140348.11b7629c@posting.google.com...

Hi all,
I am stuck with this problem of a BGA chip getting fried within a
few seconds of powerup.The chip takes in 2 power supplies.1v for core
and a 3v3 for i/o's.There are no overshoots or undershoots that i can
see in the oscilloscopes.

Check the power sequencing. Does the chip require 3v3 to be up before the
1v?

What about inputs to the chip? Do they appear before the rails are up?
Perhaps you are "latching up" an unprotected input pin (perhaps an analog
I/O pin- they don't always have protection).

Are the clocks running? Some dynamic devices get a bit hot and bothered if
they aren't clocked.

Heatsinks not big enough? With some BGA you need to extract heat through the
PCB as well as from the top of. They need the correct PCB footprint and
weight of copper.

Reset not long enough to allow correct operation? Bit unlikely though.

 

[DaveC]

On Wed, 14 Jul 2004 08:43:21 -0700, John Larkin wrote
(in article <t0laf0poeo56jdqvqocf4hp08jb59rvgek@4ax.com&gt:

If it's a ram-based FPGA, it could be a weird configuration file. It's
possible to program some of these parts to self-destruct.

Recollection of Motorola's "CFBU" (catch fire and burn up opcode. That
was that in the first 6502's, wasn't it?
--
DaveC
me@privacy.net
This is an invalid return address
Please reply in the news group

 

[John Larkin]

On Wed, 14 Jul 2004 12:10:58 -0700, DaveC <me@privacy.net> wrote:

On Wed, 14 Jul 2004 08:43:21 -0700, John Larkin wrote
(in article <t0laf0poeo56jdqvqocf4hp08jb59rvgek@4ax.com&gt:

If it's a ram-based FPGA, it could be a weird configuration file. It's
possible to program some of these parts to self-destruct.

Recollection of Motorola's "CFBU" (catch fire and burn up opcode. That
was that in the first 6502's, wasn't it?

S/360 had a bunch of reserved opcodes...

http://listserv.uark.edu/scripts/wa.exe?A2=ind0406&L=vmesa-l&F=&S=&P=62319

My favorite is BKO Branch and kill operator


The PDP-11 had the (real) LandMine instruction,

MOV -(PC), -(PC)

which copied itself into all of memory.

John