Marriage is under fire!!

In article <7fg3j09sk1vlsi59ulbido2ctqi39evd96@4ax.com>,
Paul Burridge <pb@notthisbit.osiris1.co.uk> wrote:
On Sun, 29 Aug 2004 00:48:51 +0000 (UTC), kensmith@green.rahul.net
(Ken Smith) wrote:

In article <5z5Yc.3257$6o3.2610@newsread2.news.atl.earthlink.net>,
Ralph Mowery <rmowery28146@earthlink.net> wrote:
[...]
Any class ( A, B , C ) of amp can be plate modulated for AM. It is then
not really an amplifier.

I disagree with this. If the stage puts out more RF than it takes in, it
is an amplifier

By that definition, it could also be an oscillator!
Click to expand...
If you are putting RF in and getting RF out at the same frequency, in any
reasonable case the circuit is acting as an amplifier. The circuit may
well oscillate when no input is applied. This sort of amplifier was very
common in the past and still is somewhat common.

A super-regen receiver is the most obvious example. Many tube based FM
receiver designs had a FM detector that would oscillate with no input
signal. The "burst lock oscillator" in a TV is in fact a very narrow pass
filter and amplifier when there is a burst to lock to. With no burst it
oscillates.


--
--
kensmith@rahul.net forging knowledge
 
On Sun, 29 Aug 2004 12:08:37 -0700, John Larkin
<jjlarkin@highlandSNIPtechTHISnologyPLEASE.com> wrote:

On Sun, 29 Aug 2004 19:34:57 +0100, Paul Burridge
pb@notthisbit.osiris1.co.uk> wrote:

On Sun, 29 Aug 2004 11:12:18 -0700, John Larkin
jjlarkin@highlandSNIPtechTHISnologyPLEASE.com> wrote:

Tube class-C amps often self-bias (via grid rectification) when
operating normally. Without drive, they often have high, sometimes
dangerous, idle currents.

Toobz? I was talking of transistors. Many tranny designs for Class C
RF utilize self-bias, too, but there is still no quiescent current!


What makes an amp Class C is a low conduction angle while operating.
When it's not operating, is has no class at all.
Click to expand...
---
I ran into a surgeon like that once...

--
John Fields
 
In article <4kg3j0d5nhifl6mktp474qlkjmoj11aj3f@4ax.com>,
Paul Burridge <pb@notthisbit.osiris1.co.uk> wrote:
On Sun, 29 Aug 2004 00:46:11 +0000 (UTC), kensmith@green.rahul.net
(Ken Smith) wrote:

If this isn't the slow modulation case, for a single device RF output
stage to work as a linear you need to bias it to about the point where gm
is 1/2 the "mid current" gm. This makes the stage class AB.

If you want to go towards class B or C there are things you can do in the
slow modulation case. Basically as the RF input increases, you move into
class C and as it decreases you move back towards AB. Moving to class C
lowers the output power for large signals a bit so the AB class's standing
current can be reduced by some amount.

Can't agree. If you're running any amount of standing current, then it
ain't class C.
Click to expand...
If the conduction angle is less than 180 degrees it is class C. Note that
I said "you move into class C" this means the amplifier isn't always
running as class C. It only runs in class C with large signals. Since
the large signal case is were the losses really matter, this sort of
design will work quite a bit better than a simple class AB circuit.

--
--
kensmith@rahul.net forging knowledge
 
Could a solenoid be constructed to mimic
the proper valve position vs time curve of a
engine cam shaft?
===================
Click to expand...
http://rbowes1.11net.com/dbowes/
 
The advent of flat panel displays is putting price pressure on the CRT's.
 
Let me guess... it's a LaserJet 4 or 5. It's keeping itself warmed up,
using heating coils.

We have moved to newer printers because the old ones were drawing so much
current they would disturb computers on the same circuit.
 
On Sun, 29 Aug 2004 15:04:53 -0500, John Fields wrote:

On Sun, 29 Aug 2004 12:08:37 -0700, John Larkin
jjlarkin@highlandSNIPtechTHISnologyPLEASE.com> wrote:

On Sun, 29 Aug 2004 19:34:57 +0100, Paul Burridge
pb@notthisbit.osiris1.co.uk> wrote:

On Sun, 29 Aug 2004 11:12:18 -0700, John Larkin
jjlarkin@highlandSNIPtechTHISnologyPLEASE.com> wrote:

Tube class-C amps often self-bias (via grid rectification) when
operating normally. Without drive, they often have high, sometimes
dangerous, idle currents.

Toobz? I was talking of transistors. Many tranny designs for Class C
RF utilize self-bias, too, but there is still no quiescent current!


What makes an amp Class C is a low conduction angle while operating.
When it's not operating, is has no class at all.

---
I ran into a surgeon like that once...
Click to expand...
Burridge? <shudder>

--
Keith
 
On 29 Aug 2004 20:01:00 GMT, Ian Stirling <root@mauve.demon.co.uk>
wrote:

it's the heating element for the fuser, maybe a halogen lamp element
inside the fuser cylinder. You're seeing a resistive current draw from
the 60 Hz mains that tapers off as the element heats up and increases
resistance. Your 26 amp initial draw is reasonable for a cold
(relatively) element resistance of around 5 ohms.

One 'easy' way might be to find an appropriate NTC thermistor, and put
it in series with the lamp.
Click to expand...
would blow it; mine halogen lamp element inside the fuser cylinder has
400W ...
--
Regards, SPAJKY ÂŽ
& visit my site @ http://www.spajky.vze.com
"Tualatin OC-ed / BX-Slot1 / inaudible setup!"
E-mail AntiSpam: remove ##
 
On 29 Aug 2004 13:15:33 -0700, dude17@sacbeemail.com (~Dude17~) wrote:

I know things are ALWAYS changing for the computer itself, but I
figure television /CRT technology is pretty much matured.

You can get a 19" CRT for $200 today that has a completely flat tube.
I remember high end 17" CRT PC monitors were over $1,000 in 1995.
What was so different back then?
Click to expand...
mass production , strong competition & price "wars"?
--
Regards, SPAJKY ÂŽ
& visit my site @ http://www.spajky.vze.com
"Tualatin OC-ed / BX-Slot1 / inaudible setup!"
E-mail AntiSpam: remove ##
 
~Dude17~ wrote:

X-No-Archive: Yes

I've got a laser printer that draws current in spikes and it
makes the lights flicker as well as causing a UPS on the same circuit
to switch over to battery due to excessive dV/dT. Unfortunately, I
don't have a way of putting the printer on its own circuit unless I
want to use a long extension cord.
Click to expand...

I have a Brother HL-1470N, at home, which exhibits the same symptoms.

I too was thinking of posting about this. I am trying to figure out
what to do about this. In my case, I simply moved it off of the UPS,
but the lights flickering is still undesirable.

Is there anything I can actually do about this?
 
"no_one" <no_one@earthlink.net> wrote in message
news:F8pYc.1914$8d1.375@newsread2.news.pas.earthlink.net...
why don't you steal the guts from one of those singing bass fish things;
http://www.howstuffworks.com/singing-fish.htm
Click to expand...
I'm sure they're using simple level triggers.

I think Robert is on track in his suggestion of a low power microcontroller.
A mic, a rectifier and a cap before the AD of the uC. The uC should wake up
once in a while to measure the level and integrate. Probably it'll prove OK
to do a discrete mesaurements once or twice per second - allowing the mic to
be powered down.

/Anders
 
I read in sci.electronics.design that Anthony Guzzi
<dukeofurl@sonic.net> wrote (in <maBYc.11003$54.150804@typhoon.sonic.net
) about 'Laser printer draws current in a spike, what for?', on Mon, 30
Aug 2004:
~Dude17~ wrote:

X-No-Archive: Yes

I've got a laser printer that draws current in spikes and it
makes the lights flicker as well as causing a UPS on the same circuit
to switch over to battery due to excessive dV/dT. Unfortunately, I
don't have a way of putting the printer on its own circuit unless I
want to use a long extension cord.


I have a Brother HL-1470N, at home, which exhibits the same symptoms.

I too was thinking of posting about this. I am trying to figure out
what to do about this. In my case, I simply moved it off of the UPS,
but the lights flickering is still undesirable.

Is there anything I can actually do about this?
Click to expand...
You definitely did the right thing in moving it off the UPS. There is no
justification, normally, for running a printer off a UPS, and, as you
see, it is a very stressful load which could adversely affect the UPS
life or reliability.

A laser printer sold in Europe must conform to EN 61000-3-2 and -3. The
former is concerned (indirectly) with limiting the peak pulse current,
cycle by cycle, while the latter is concerned with limiting flicker. But
you'd need to run it from 240 V - either directly or with 120:240
transformer. The frequency doesn't matter.

According to US sources, problems such as you report never occur, and
they don't need to implement the IEC versions of those ENs as US
standards. So you are actually just imagining the flicker. (;-)
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk
 
Holden Bonwit wrote:

I was curious if anyone knew of a vendor who makes/sells high voltage
LEDs. I have a 25 volt power supply, and for various reasons don't
want to step down the voltage to ~12 volts with a voltage regulator.
Click to expand...
LEDs are current, not voltage driven. In other words, you need a current
limiting resistor in series with the LED. You can calculate the
resistance required by (Vin - Vled)/ current, current is usually 20 mA.
If the voltage is likely to change, or if you are to lazy to do the
calculation, use a FET as constant current source, I have posted the
schematic here a couple of times, use google.

You can also buy LEDs with that FET integrated on the chip, these work
on any DC source up to 30 V.
 
On Mon, 30 Aug 2004 09:34:55 +0100, John Woodgate
<jmw@jmwa.demon.contraspam.yuk> wrote:


A laser printer sold in Europe must conform to EN 61000-3-2 and -3. The
former is concerned (indirectly) with limiting the peak pulse current,
cycle by cycle, while the latter is concerned with limiting flicker. But
you'd need to run it from 240 V - either directly or with 120:240
transformer. The frequency doesn't matter.

According to US sources, problems such as you report never occur, and
they don't need to implement the IEC versions of those ENs as US
standards. So you are actually just imagining the flicker. (;-)
--
Click to expand...
I've got a Brother HL-1440 that also causes me to imagine the
lights are flickering. ;-)


Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com
 
What you're seeing, is the cycling of the heater for the fusing roller.
This roller melts the toner into the paper.
Without it, your print would simply blow away.
It's integral to the operation of the printer.. Just don't put it behind
your ups. There's really no need anyway, if the power goes out, then just
restart the print later.
--
KC6ETE Dave's Engineering Page, www.dvanhorn.org
Microcontroller Consultant, specializing in Atmel AVR
 
In article <MMyWVDBvauMBFw+u@jmwa.demon.co.uk>,
John Woodgate <jmw@jmwa.demon.contraspam.yuk> writes:
According to US sources, problems such as you report never occur, and
they don't need to implement the IEC versions of those ENs as US
standards. So you are actually just imagining the flicker. (;-)
Click to expand...
The irony is this is quite common in the US, but I've never seen
it happening in a 240V country ;-)

--
Andrew Gabriel
Consultant Software Engineer
 
On Mon, 30 Aug 2004 18:53:56 +0100, John Woodgate
<jmw@jmwa.demon.contraspam.yuk> wrote:

I read in sci.electronics.design that John Larkin <jjlarkin@highSNIPland
THIStechPLEASEnology.com> wrote (in <7fo6j05rp857et2n7tbqlp12bavl48qrrv@
4ax.com>) about 'How to bias a MOSFET amp?', on Mon, 30 Aug 2004:
He said surgeon, not sturgeon.


But, being male, PB is not even a potential source of caviar.
Click to expand...
Hey ladies, gimme a break will ya? Don't make your PMS my problem. ;-)
--

"What is now proved was once only imagin'd." - William Blake, 1793.
 
andrew@cucumber.demon.co.uk (Andrew Gabriel) wrote:
In article <MMyWVDBvauMBFw+u@jmwa.demon.co.uk>,
John Woodgate <jmw@jmwa.demon.contraspam.yuk> writes:
According to US sources, problems such as you report never occur, and
they don't need to implement the IEC versions of those ENs as US
standards. So you are actually just imagining the flicker. (;-)

The irony is this is quite common in the US, but I've never seen
it happening in a 240V country ;-)
Click to expand...
Well... obviously the current is halved, but...

A laser printer that dims the lights???? Jus how common is
that, really?

--
FloydL. Davidson <http://web.newsguy.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska) floyd@barrow.com
 
In sci.electronics.design Spehro Pefhany <speffSNIP@interlogdotyou.knowwhat> wrote:
On Mon, 30 Aug 2004 12:03:06 -0800, the renowned floyd@barrow.com
(Floyd L. Davidson) wrote:

Well... obviously the current is halved, but...

A laser printer that dims the lights???? Jus how common is
that, really?

I've seen it (NEC Silentwriter LC890). It's just a flicker- the
problem is that the flicker is repetitive with the control of the
fusion roller temperature and continued as long as the printer was
switched on. My modern HP doesn't appear to do anything like that.
Click to expand...
I wonder how often 4 or 5 printers on one circuit might cause the
fuse to pop, if "idle".
 
I read in sci.electronics.design that phil-news-nospam@ipal.net wrote
(in <cgvv6622lj3@news1.newsguy.com>) about 'Laser printer draws current
in a spike, what for?', on Mon, 30 Aug 2004:

I don't know that this would affect it all that much, but I've also
heard that in UK, available fault current at homes tends to be higher
than in the US (one transformer serving a whole block of homes instead
of the typical 1 to 4 in the US). I'm not sure I'd really like having
higher available fault current.
Click to expand...
The transformer impedance is lower but the cables add impedance (mostly
inductance unless they are buried coaxials). The typical fault currents
in UK and US are not a lot different, i.e. in USA the impedance of a 120
V supply is about half that of a European 230 V supply. But note
'typical'. There is a lot of variation.
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk
 
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