audio recording on IC -help wanted

[Graham W]

larwe@larwe.com wrote:

mc wrote:

surprised if the clocking frequency in a home PC machine is
drifting about 1% to 2%. As long as everything keeps properly
synchronized there will be

That would be a gigantic drift for even a very cheap crystal. I
think 1/10,000 is more typical of what would be a large drift from a
low-quality crystal.

The battery-powered RTC clock is frequently VERY inaccurate, though.
For reasons I've never had explained to me, they almost always have a
trimcap on that xtal. Their Q/C processes to set that trimcap appear
to be FUBAR.

What trimcap? I've never seen one in a PC RTC circuit and, golly, does
it need it!


--
Graham W http://www.gcw.org.uk/ PGM-FI page updated, Graphics Tutorial
WIMBORNE http://www.wessex-astro-society.freeserve.co.uk/ Wessex
Dorset UK Astro Society's Web pages, Info, Meeting Dates, Sites & Maps
Change 'news' to 'sewn' in my Reply address to avoid my spam filter.

 

[Richard Freeman]

<larwe@larwe.com> wrote in message
news:1109016257.420847.117250@f14g2000cwb.googlegroups.com...

The battery-powered RTC clock is frequently VERY inaccurate,
though.
For reasons I've never had explained to me, they almost always have
a
trimcap on that xtal. Their Q/C processes to set that trimcap
appear

What trimcap? I've never seen one in a PC RTC circuit and, golly,
does
it need it!

Maybe your motherboard collection differs from mine. But every board
I've owned (except some of the laptops) has had a trimcap.

Mystery why they bother to put such fine-tuning on there, since it is
very common to get as much as 10 seconds drift per day!

I would not have expected an un-trimmed Crystal to drift more than 100 Parts
per Million or 86.4 mS per day, the Laptop I am using at the moment is still
within a Second of the Talking clock and I set it 3-4 Months ago.
I am sure I would have noticed if Clocks on any PC's I used were losing or
gaining 10 Seconds a day

 

[MC]

Richard Freeman wrote:

larwe@larwe.com> wrote in message
news:1109016257.420847.117250@f14g2000cwb.googlegroups.com...

The battery-powered RTC clock is frequently VERY inaccurate,

though.

For reasons I've never had explained to me, they almost always have

a

trimcap on that xtal. Their Q/C processes to set that trimcap

appear

What trimcap? I've never seen one in a PC RTC circuit and, golly,

does

it need it!

Maybe your motherboard collection differs from mine. But every board
I've owned (except some of the laptops) has had a trimcap.

Mystery why they bother to put such fine-tuning on there, since it is
very common to get as much as 10 seconds drift per day!


I would not have expected an un-trimmed Crystal to drift more than 100 Parts
per Million or 86.4 mS per day, the Laptop I am using at the moment is still
within a Second of the Talking clock and I set it 3-4 Months ago.
I am sure I would have noticed if Clocks on any PC's I used were losing or
gaining 10 Seconds a day

You're fortunate...
I've only had one laptop out of 4 that didn't drift in time too much.
My current one loses about 4 seconds per day., my previous one
gained about 2 seconds per day.
The PC battery-backed-up clock system was 'adequate' when it was
created back in the mid 1980's, but unfortunately that part of
the PC architecture hasn't changed much since then.

 

[Phil Allison]

"Richard Freeman"

I would not have expected an un-trimmed Crystal to drift more than 100
Parts per Million or 86.4 mS per day,

** 100 ppm = 1 part in 10,000.

A day has 24 x 60 x 60 seconds or 86,400 seconds.

So a 100 pm error is 8.64 seconds !!!

You are only 1000 times out.

the Laptop I am using at the moment is still within a Second of the Talking
clock and I set it 3-4 Months ago.

** Sure - drift is nearly all due the tempco of the crystal.

If the AVERAGE temp value is steady from day to day then there is virtually
no DRIFT.

There may well be fixed setting error though.

I am sure I would have noticed if Clocks on any PC's I used were losing or
gaining 10 Seconds a day

** The tempco drift is only a few ppm *per degree C* for most crystals,
over the range from 10 to 35 C.

The indoor temp averaged over a month varies only a few degrees compared
with the previous or next month.

So, the month to month variation should be maybe +/- 10ppm or 0.86
seconds.

Seems about right to me.



................ Phil

 

[mc]

"MC" <MC@nonexistant.place> wrote in message
news:cvf2bo$msb$1@news-02.connect.com.au...

You're fortunate...
I've only had one laptop out of 4 that didn't drift in time too much.
My current one loses about 4 seconds per day., my previous one
gained about 2 seconds per day.
The PC battery-backed-up clock system was 'adequate' when it was
created back in the mid 1980's, but unfortunately that part of
the PC architecture hasn't changed much since then.

Do they use crystals that are much lower-grade than even the cheapest RF
crystals?

Ceramic resonators, maybe?

Do they have firmware that is incorrect? Maybe the problem isn't just
frequency.

 

[MC]

mc wrote:

You're fortunate...
I've only had one laptop out of 4 that didn't drift in time too much.
My current one loses about 4 seconds per day., my previous one
gained about 2 seconds per day.
The PC battery-backed-up clock system was 'adequate' when it was
created back in the mid 1980's, but unfortunately that part of
the PC architecture hasn't changed much since then.

Do they use crystals that are much lower-grade than even the cheapest RF
crystals?

Ceramic resonators, maybe?

Who knows ?. Every manufacturer will use what they want at the time.

Do they have firmware that is incorrect? Maybe the problem isn't just
frequency.

It's not a firmware issue, more a situation that the hardware timekeeper
is not intended to be super accurate and therefore providing things to
make it more accurate (such as temperature control and accurate
oscillators) can become expensive.

 

[Larry Brasfield]

"mc" <mc_no_spam@uga.edu> wrote in message
news:421b4fdc@mustang.speedfactory.net...

"MC" <MC@nonexistant.place> wrote in message news:cvf2bo$msb$1@news-02.connect.com.au...

You're fortunate...
I've only had one laptop out of 4 that didn't drift in time too much.
My current one loses about 4 seconds per day., my previous one
gained about 2 seconds per day.
The PC battery-backed-up clock system was 'adequate' when it was
created back in the mid 1980's, but unfortunately that part of
the PC architecture hasn't changed much since then.

Do they use crystals that are much lower-grade than even the cheapest RF crystals?

Ceramic resonators, maybe?

Do they have firmware that is incorrect? Maybe the problem isn't just frequency.

The reason that PC clocks drift is that the crystal
is cut for a different mode of vibration than most
higher frequency crystals. To save power, the
crystal oscillator that runs off of battery in your
PC operates at 32768 Hz (or something nearby).
The crystal vibrates in a flexing mode rather than
the more stable shear modes because that is the
only way to get the frequency down without
having to make a truly huge device that would
require more power to keep going.

--
--Larry Brasfield
email: donotspam_larry_brasfield@hotmail.com
Above views may belong only to me.

 

[Tim Shoppa]

I find it a model of clarity.
[...]
I can't find any reference to a 74hc9046.

My frustration was largely because a search on the Philips website
turned up two hits on 74HC9046 but neither of them were useful for
anything. In fact, the part number is 74HCT9046, and that search
yields useful results.

As others have noted, the website is a bit graphics-heavy and
Javascript-buggy, but I worked around those difficulties without a lot
of pain. I prefer, say, the TI or NatSemi websites for a lot of
things, but even those have their quirks.

Tim.

 

[David L. Jones]

Neo wrote:

I am about to purchase a temperature controlled soldering station.

Seems that the Hakko936 are very well known.

However, I have been unable to find any feedback on Goot stations.

These are sold in Australia by Jaycar.

https://secure2.vivid-design.com.au...x=&SUBCATID=627

Anybody tried these?

How do they measure up to Hakko's?

TIA,
Neo.

Go for the Hakko. You'll be guaranteed to get spares in the future
along with a whole range of tips and accesories. The Hakkos are very
reliable too, you simply cannot go wrong buying a Hakko.

Anything Jaycar sell will certainly be inferior to the Hakko.

Dave

 

[Anthony Fremont]

Jim wrote:

Hi guys

I want to build this simple circuit to power my Xbox on and off via
an IR remote control

http://xirremote.tripod.com/

Whilst I'm OK with soldering and building the circuit, I've got no
idea when it comes to components. Could someone have a quick run
through these parts and make sure they are what I need (the urls are
to the RS components UK website and Maplins UK)

Sorry, your links don't seem to work now.

IC - http://tinyurl.com/2dfdzb

That is a PIC, you can get them many places. The issue will be getting it
programmed. I can probably help you out since the HEX file is available. I
don't see any source code though. :-(

IR Reciver - http://tinyurl.com/2wglzf

These are pretty generic, so any will do fine. It just has to be made for
the right frequency (56kHz aparently).

Diode - http://tinyurl.com/29xk27
R1 & R2 - http://tinyurl.com/yo7d3o (codes D10K & D47K)

Any 1/4W or 1/8W carbon-comp should do.

C1 - http://tinyurl.com/ytop3m (code BX03D)
C2 - got no idea anyone help please

You want a ceramice disc for C1 and an electrolytic for C2. Since the
voltage in the circuit is so low, almost any will do.

I looked at the schematic, and there are some things I wonder about. Most
IR receivers have an open-collector output (meaning they can't supply a
positive drive voltage on their own). I would expect to see an external
pull-up resistor, I assume the creator is using the "weak" pull-ups built
into the PIC. This may work ok, but may also be prone to noise pickup
especially if the wires are longish.

Too bad he didn't seem to provide the source, or I could have easily
converted it to run on a smaller, cheaper PIC that I happen to have on hand.

 

[Franc Zabkar]

On Sat, 24 Feb 2007 11:13:58 GMT, "Jim" <jim@home.com> put finger to
keyboard and composed:

Hi, thanks to all that replied

Think I'm getting there.

I do have an 'Elvis' programmer which does PIC chips left over from when I
used to play about with satllite TV, just need to dig it out and refresh
myself how to use it !

My understanding is that the hex code will program the PIC to react to a
given IR code (the 0 button and diplay buttons on the Xbox remote if I've
read the xirremote site correctly) My plan is to download these codes into
my learning remote so that I only need the one remote to control all my kit

Any other input still welcome

Thanks

Jim

Just a question to those who are watching this thread.

Are learning remotes fixed frequency devices (eg 38kHz) or are they
able to learn the modulation frequency in addition to the various
codes?

I can envisage sensitivity problems if the remote's frequency is fixed
at 38kHz when the Xbox expects 56kHz.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

 

[Spehro Pefhany]

On Thu, 15 Mar 2007 22:21:33 +0000, the renowned Brendan Gillatt
<brendan@brendanREMOVETHISgillatt.co.uk> wrote:

On Thu, 15 Mar 2007 13:52:06 -0700, John E. <incognito@yahoo.com
wrote:

PIC is king, I'm sure. But I'd like to hear from those who are using all
brands. Whichever you use, what do you like about it? What don't you like
about others? Suggestions re. learning?

I've programmed 68000 assembly and some higher-level languages (FORTRAN; some
BASIC; COBOL if forced to admit it), so no stranger to programming, per se.

Thanks,

You can't really say what one is 'best' - it depends on what you
really want to do.

Even with PICs it's hard to say which is best - from tiny 8 pin
controllers to massive 44 pin processing beasts with hundreds in
between.

Not to mention the 64, 68, 80 and 100-pin ones.

PIC assembly is tiresome at the least. The instruction set is tiny
which means that they take considerably more coding than, say, x86
assembly.

There are several flavo[r]s to PIC assembly.

Atmel micros are becoming popular too - though I haven't had any
experience with them.

Depending on what you want, you may look at *gasp* Basic Stamps, made
by Parralax (sp?) if you know BASIC well - just don't count on amazing
performance.

That thing is not 'a microcontroller'.

As to the original question.. it really depends on the application and
the peripherals you might need. If you need Ethernet and/or USB on
board, that's one thing (you'll almost certainly want something with a
decent C compiler and available protocol stack), if you just want to
diddle some bits fast, or do a relatively slow PID control that's
another. If you need 10, 12, or 24 bits of ADC, multiple PWMs,
quadrature input, direct display drive, etc. etc. that may play a
great role. The choice of core is only one consideration among many.


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

 

[Anthony Fremont]

Eeyore wrote:

Anthony Fremont wrote:

Multisourced, that's another misrepresentation. For the most part,
chips from different vendors are just similar archetectures, not
"compatible" chips insofar as actually being able to drop one in
place of another. Not to mention how vastly incompatible the code
internals are for anything but the most basic peripherals.

But that's just my opinion. ;-)

Eh ?

The various 8051 clones from various manufacturers are completely
compatible in every respect. That's one of the joys of the part. Such
changes as have been made are backwardly compatible even with no code
change too.

Things must have changed then. Only the barest parts would be compatible.
As soon as you start adding extra peripherals (and these _are_ the chips
that get used in production, not the 8051 true clones) things change allot.
So it's true that you could probably get away with dropping an Atmel 89c52
in place of a vintage 8052, it likely wouldn't work the other way around
since the Atmel part has "extensions". As soon as people utilize the
extensions, compatibility disappears. no?

 

[Michael A. Terrell]

LVMarc wrote:

 

[RST Engineering (jw)]

Nobody, at least nobody when I looked a few years ago to shield the VCO in
the transmitter. What we wound up doing was buying shim brass from
McMaster-Carr and having the local machine shop whack up a full roll into
perimeter lengths and covers. Use bus-bar wire through the pc board a
little less than the height of the shield every so often around the INside
of the perimeter and overlap the ends. Fasten the ends with an alligator
clip and solder the ends together. THen solder the busbar "fence posts" to
the inside of the shield. Get the sucker to working and then tack-solder
the lid into place every so often. "every so often" is a trial and error
until you get the shielding you need.

If you only need a few hundred, I'd use the 0.001-0.002" shim stock, a
ruler, and an exacto knife. Give the kid next door two bits apiece to slice
and dice. Tell him to use gloves unless you are particularly fond of blood
on the shielding.

Jim



"Joerg" <notthisjoergsch@removethispacbell.net> wrote in message
news:I8gQh.1232$w41.931@newssvr19.news.prodigy.net...
> Where can one buy those tin-plated RF shields with snap-on lids?

 

[RST Engineering (jw)]

A what?

{;-)


Jim



They also don't really know what a

transistor is or how it works :-(

--
Regards, Joerg

http://www.analogconsultants.com

 

[RST Engineering (jw)]

The usual last words of a redneck aviator? (see below)



"Joerg" <notthisjoergsch@removethispacbell.net> wrote in message
news:3ZvRh.14924$Um6.6286@newssvr12.news.prodigy.net...

RST Engineering (jw) wrote:

A what?

{;-)


A transister is them thar thang that's gitten the ballgame from the errial
into the loudspeaker so ya can listen to it when sittin' on the tracter
;-)

Hey, y'all, hold my beer and watch THIS.


{;-)

Jim

 

[Green Xenon [Radium]]

On Sep 23, 2:36 pm, "Brian Gregory [UK]" <n...@bgdsv.co.uk> wrote:

No.

These are like special modified forms of AM.

You can only use these to reduce
bandwidth of an FM signal
in the same way that you
can use AM to reduce the
bandwidth of an FM signal.
It just won't be FM any more.

Would using Quadrature Frequency Modulation be of any help?

Quadrature Amplitude Modulation uses a combo of AM and Phase-Shift-Keying.

So QFM would use a combination of FM and PSK. Would this decrease the
bandwidth required for broadcasting FM luminance video signals?

 

[Green Xenon [Radium]]

On Sep 23, 3:02 pm, Brendan Gillatt
<brendanREMOVET...@brendanREMOVETHISgillatt.co.uk> wrote in
http://groups.google.com/group/uk.tech.digital-tv/msg/4c903b0a453a39fa :

Okay now you're actualy irritating me quite a LOT.

How so? I am just asking extremely interesting questions about video
technology.

Please, do yourself a favour: buy an Amazon book voucher and shut up.

I’ve tried painfully hard to answer my questions doing my own research
-- including reading information from books. I still haven’t found
answers to my questions. That is why I am turning to NGs for assistance.

Is Quadrature Frequency Modulation used? What for?

AFAIK, Quadrature Amplitude Modulation uses a combo of AM and
Phase-Shift-Keying.

So QFM would use a combination of FM and PSK. Would this decrease the
bandwidth required for broadcasting FM luminance video signals?

I did a Google Search for “Quadrature Frequency Modulation” on
http://www.google.com/search?hl=en&lr=&q=%22Quadrature+Frequency+Modulation+%22&btnG=Search

None of those pages made any sense to me.

One major reason the luminance signals of television are broadcasted on
an AM-carrier instead of an FM-carrier is because FM requires large
amounts of bandwidth. Is there a way to use FM video without hogging so
much bandwidth using QFM?

Quotes from
http://groups.google.com/group/sci.electronics.basics/msg/0c013cf5371da8dc?hl=en&
:

Multiple-level quadrature modulation,
"constellation modulation",
is most common for packing
lots of bits per Hz of bandwidth.
The more you pack,
the better the s/n ratio has to be.
http://en.wikipedia.org/wiki/Quadrature_amplitude_modulation

http://en.wikipedia.org/wiki/Constellation_diagram

Does this mean that the FM-equivalents-of-QAM and Constellation
Modulation can -- at least in theory -- be applied to FM video so that
excessive bandwidth is not needed? If so, then what would be the minimum
radio-frequency required to transmit the video signal? Is a 150 kHz
radio-frequency sufficient to be an FM carrier for this video signal?

Constellation modulation is a type of AM. What’s the FM-equivalent of
constellation modulation?

Has multiple-level QFM ever been used for video before?