Chip with simple program for Toy

[Michael A. Terrell]

Joerg wrote:

JosephKK wrote:

Joerg notthisjoergsch@removethispacbell.net posted to
sci.electronics.design:


Richard Fry wrote:


Other than brief portions of the evening news the question arises:
What's the whole point in restoration these days? If OTA-TV really
goes digital some distant day we might not even bother buying a new
set.

_________

Accurate colour reproduction requires accurate transmission of the
luminance (brightness) value of each colour, which is set by a
specific, DC-coupled voltage. If the video signal was transmitted
using AC coupling, then luminance values would be a function of the
average voltage of the video waveform.

For that matter accurate monochome reproduction also requires DC
coupling, but it is not as objectionable if not used (cheap TV set,
etc).

Also - the purpose of inverting video for transmission is to
transmit the peaks of sync pulses at +100% modulation, which allows
TV receivers to show the most stable picture in the presence of
noise (eg, fringes of the coverage area of the TV station).

RF
RCA Broadcast Field Engineer, retired


I know how it works, Richard. My point was, why restore the clamp
level or any other level if the contents of the transmission itself
ain't worth watching? It they did more re-runs of Andy Griffith or
Bonanza or whatever, ok, but not with the average programming these
days.



True, but a lot of the best stuff is B&W (notably much of Andy
Griffith, Bonanza, The Outer Limits, Masterpiece Theater, and so on).
Often a lot of the old good stuff is available on cable or satellite
that OTA stations cannot use because the audience is too small.


Yes, but then they make us pay around $50/month where $49 of those
Dollars are going towards junk I don't care for. Luckily there is the
VCR. Occasionally our video rental place in town has an old movie. Much
of that has never even been ported to DVD.

--
Regards, Joerg

http://www.analogconsultants.com

Check the dollar stores. Lots of old movies on DVD for a buck, and
every batch they get is different.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

 

[Don Bowey]

On 9/28/07 9:24 AM, in article 46fd2830$0$32509$4c368faf@roadrunner.com,
"Green Xenon [Radium]" <glucegen1@excite.com> wrote:

Hi:

Will someone please assist me in answering my questions in the below thread?

http://groups.google.com/group/bit.listserv.deaf-l/browse_frm/thread/10f154c72
15a31a6?scoring=d&hl=en


Thanks for your cooperation and understanding,

Radium

You have certainly made a mess of making google searches. They should flush
all your posts so anyone wanting to search your latest interest might find
rational information.

 

[Richard Crowley]

"Green Xenon [Radium]" wrote ...

Will someone please assist me in answering my questions in the below
thread?

http://groups.google.com/group/bit.listserv.deaf-l/browse_frm/thread/10f154c7215a31a6?scoring=d&hl=en


Thanks for your cooperation and understanding,

Hard to cooperate or understand when you make up acronyms
apparently out of thin air and then demand that they be defined
and explained. It is the kind of scenario that would make a good
scene on Monty Python.

If "EDTN" is really an acronym that you didn't make up yourself,
tell us where you saw it. Even better trace it back through the
context yourself. You might learn something about research
instead of asking everyone else to do it for you.

 

[Don Bowey]

On 9/28/07 11:04 AM, in article 46fd3f93$0$20627$4c368faf@roadrunner.com,
"Green Xenon [Radium]" <glucegen1@excite.com> wrote:

Richard Crowley wrote:

If "EDTN" is really an acronym that you didn't make up yourself,
tell us where you saw it.

Quotes from http://www.teletec.co.uk/minicoms/uniphone.php :

"Baudot, CCITT and EDTN codes"

Quotes from
http://groups.google.com/group/24hoursupport.helpdesk/msg/69ccb7c241b916d2?hl=
en&
:

"It's a long time since I had anything to do with this but the 'normal'
standards were/are Baudot, CCITT and EDTN."

Now would someone please assist me on this?

That you provide bullshit as information, doesn't help.

Your answer is here..... Google for "tted directive"

Include the quote marks.

 

[Richard Crowley]

"Green Xenon [Radium]" <glucegen1@excite.com> wrote in message
news:46fd3f93$0$20627$4c368faf@roadrunner.com...

Richard Crowley wrote:

If "EDTN" is really an acronym that you didn't make up yourself,
tell us where you saw it.

Quotes from http://www.teletec.co.uk/minicoms/uniphone.php :

"Baudot, CCITT and EDTN codes"

Quotes from
http://groups.google.com/group/24hoursupport.helpdesk/msg/69ccb7c241b916d2?hl=en& :

"It's a long time since I had anything to do with this but the 'normal'
standards were/are Baudot, CCITT and EDTN."

Now would someone please assist me on this?

What happened when you asked Teletec?
What happened when you asked Peter Andrews?

Just throwing out questions like this clearly isn't getting you anywhere.
Your tone of insistence isn't winning you any friends, either.

 

[Jerry Avins]

Green Xenon [Radium] wrote:

Richard Crowley wrote:

If "EDTN" is really an acronym that you didn't make up yourself,
tell us where you saw it.

Quotes from http://www.teletec.co.uk/minicoms/uniphone.php :

"Baudot, CCITT and EDTN codes"

Quotes from
http://groups.google.com/group/24hoursupport.helpdesk/msg/69ccb7c241b916d2?hl=en&
:

"It's a long time since I had anything to do with this but the 'normal'
standards were/are Baudot, CCITT and EDTN."

Now would someone please assist me on this?

Don't believe everything you read. Baudot code was a five-bit code for a
teletype-like machine (with two modal shift characters so some keys had
three meanings). CCITT was a standards organization, now superceded. For
all I know, Baudot may have been the subject of one of their standards.

What gives you an idea that EDTN has anything to do with deafness? If it
does, it may be similar to TTY/TDD in the U.S.

Jerry
--
Engineering is the art of making what you want from things you can get.
ÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻ

 

[IanB]

On Fri, 28 Sep 2007 14:51:56 -0400, Jerry Avins <jya@ieee.org> wrote:

What gives you an idea that EDTN has anything to do with deafness? If it
does, it may be similar to TTY/TDD in the U.S.

It's the European Deaf Telephone (Network) that is used in a few
European countries - Germany and Switzerland for example. It uses V21
modulation, but only one channel, and runs at 110 baud.

Took me less than 5 minutes to find using a search engine - the OP
couldn't have been trying too hard.
--
Ian

The from address is (currently) valid

 

[Green Xenon [Radium]]

IanB wrote:

"
glucegen1@excite.com> wrote:

Specifically, where did you find
that EDTN is “European Deaf Telephone Network”?

I didn't. The "Network" bit was in brackets because I meant, but
forgot, to put a question mark in there as well.

So, IOW, you don't know for sure that EDTN equates to “European Deaf
Telephone Network”? I was afraid that would happen.

Whenever I've asked about EDTN [in relation to TDD], anyone who does
give an answer does not seem to know whether it is 100% correct. So my
suspicion was confirmed. !#%!$

Not trying to be a nuisance but I’m going crazy because of the
difficulty in answering my question.

Anyways, I am going to read the "TTE directive" and hopefully it will
answer my question.

 

[Green Xenon [Radium]]

Richard Owlett wrote:

Using *_ONLY_* information from his "Fri, 28 Sep 2007 11:04:03 -0700"
post and spending approximately 10 minutes with Google I came up with 10
URL's of agencies/firms which would be able to answer ANY legitimate
question or be willing/able to "tell him where to go"

Will you please show examples of those “10 URL's of agencies/firms”?

 

[Richard Owlett]

Green Xenon [Radium] wrote:

Richard Owlett wrote:

Using *_ONLY_* information from his "Fri, 28 Sep 2007 11:04:03 -0700"
post and spending approximately 10 minutes with Google I came up with
10 URL's of agencies/firms which would be able to answer ANY
legitimate question or be willing/able to "tell him where to go"


Will you please show examples of those “10 URL's of agencies/firms”?

If I could do it on *ONE* try using _ONLY_ info from *YOUR* post,

WHY CAN'T YOU???????????????????????????????????????

 

[Jerry Avins]

Richard Owlett wrote:

Jerry Avins wrote:
Green Xenon [Radium] wrote:

Hi:

Will someone please assist me in answering my questions in the below
thread?


...

Where did you hear of your particular combination of letters? Isn't
that a good place to start if you want to track down its meaning? You
seem to have an idea that it's a kind of telephone service for people
with a particular disability. That's pretty specific. What makes you
think so?

Jerry

Using *_ONLY_* information from his "Fri, 28 Sep 2007 11:04:03 -0700"
post and spending approximately 10 minutes with Google I came up with 10
URL's of agencies/firms which would be able to answer ANY legitimate
question or be willing/able to "tell him where to go" [intentional
double entendre]. The majority of sources are either commercial or
governmental sites. Remainder appear to be charitable sites.

All he would probably need would be a cogent reason for asking.

My grandson has (had?) Asperger's. His mother, a neatnik, did for him
everything that might be messy. When he was ten years old, She dropped
dead while preparing supper as he watched. His grandmother -- we weren't
yet married -- rushed to help pick up the pieces, and made him pancakes
for breakfast at his request. He just sat and looked at them. It turned
out that he was waiting for her to cut them up. She handed him a knife
and his education began. I first met him when she brought him to our
house a week later for a brief stay. His first act on walking through
the door was to yank my beard and announce "It's real". He had a lot of
things to learn.

He's a senior in college now, and has been living on his own for over
three years. He's learned a lot. There's hope for Radium too if he
doesn't get his pancaked cut up for him.

Jerry
--
Engineering is the art of making what you want from things you can get.
ÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻ

 

[Jerry Avins]

Green Xenon [Radium] wrote:

Don Bowey wrote:

Your answer is here..... Google for "tted directive"

Include the quote marks.

Did exactly that.

http://www.google.com/search?hl=en&q=%22tted+directive%22+&btnG=Google+Search


No results

Look, you dumb jerk. _Really look_. What did it say on that page of
"nothing"? Was there a line that started "Did you mean ...."?

Jerry
--
Engineering is the art of making what you want from things you can get.
ÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻ

 

[BobF]

http://crazy.codetroop.com/randimg/imgs/bart.gif



"Jerry Avins" <jya@ieee.org> wrote in message
news:9_idnX-GGuAQ52DbnZ2dnUVZ_jOdnZ2d@rcn.net...

wrote:
Don Bowey wrote:

Your answer is here..... Google for "tted directive"

Include the quote marks.

Did exactly that.

http://www.google.com/search?hl=en&q=%22tted+directive%22+&btnG=Google+Search
No results

Look, you dumb jerk. _Really look_. What did it say on that page of
"nothing"? Was there a line that started "Did you mean ...."?

Jerry
--
Engineering is the art of making what you want from things you can get.
ÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻ

 

[Jerry Avins]

BobF wrote:

http://crazy.codetroop.com/randimg/imgs/bart.gif

I'll see you and raise you one http://users.erols.com/jyavins/procfaq.htm

Jerry
--
Engineering is the art of making what you want from things you can get.
ÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻÂŻ

 

[Green Xenon [Radium]]

Don Bowey wrote:

You should not have stopped.

Google "tte directive"

http://www.google.com/search?hl=en&q=%22tte+directive%22+&btnG=Google+Search

Checked the 1st 10 pages. Absolutely nothing about EDTN!!!!

Checked EDTN with "tte directive" below

http://www.google.com/search?as_q=EDTN+&hl=en&num=10&btnG=Google+Search&as_epq=tte+directive&as_oq=&as_eq=edition&lr=lang_en&as_ft=i&as_filetype=&as_qdr=all&as_nlo=&as_nhi=&as_occt=any&as_dt=i&as_sitesearch=&as_rights=&safe=images

Absolutely nothing at all!!!!

I hate to be so rude and demanding but WTF is going on
here??????????!!!!!!!!!!!!?!?!?!?!?!?!?!

WTF don’t the websites about
Telecommunications-Terminal-Equipment-Directive say
anything about
EDTN????????????????!!!!!!!!!!!!!!!!!!!!!!?!?!?!?!?!?!?!?!?!?!

Before I actually did a search on "tte directive", I was extremely
optimistic and had a positive attitude that the search would tell me
what EDTN stands for [in relation to TTYs], the technical specs about
EDTN, and perhaps some EDTN numbers I could dial to listen to the
desirable tones. I was so f---------------king wrong!!!!!!!!!!!!!!!!!!!!
Now I am extremely upset and
disappointed!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

None of those sites told me what EDTN stands
for!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

I wish EDTN stood for “European Deaf Telephone Network” but it doesn’t.
My wish is way way way too good to ever be true. If EDTN stood for
“European Deaf Telephone Network”, then that would make life way too
easy!!!!!!!

If EDTN stood for “European Deaf Telephone Network”, then my search
http://www.google.com/search?hl=en&q=%22European+Deaf+Telephone+Network%22&btnG=Google+Search
would have yielded the results I am looking for.

If EDTN stood for “European Deaf Telephone Network”, then my search
http://www.google.com/search?hl=en&q=%22European+Deaf+Telephone+Network%22&btnG=Google+Search
would show a lot more information than just my previous posts!!!!!!!!!!!!!!

If EDTN stood for “European Deaf Telephone Network”, then my search
http://www.google.com/search?hl=en&q=%22European+Deaf+Telephone+Network%22&btnG=Google+Search
would describe how EDTN works and provide me with EDTN numbers which I
could dial so I could listen to EDTN tones from Switzerland!!!!!!!!!!

Unfortunately, reality -- being the sick sadistic f--k it is -- decides
otherwise. Sadly, EDTN does not stand for “European Deaf Telephone
Network” when relating to textphone terminology.

So just WTF does EDTN stand for?

Also, WTF can I find EDTN phone numbers so I can dial them and listen to
those frightening-yet-enjoyable EDTN tones from
Switzerland??????????????????!!!!!!!!!!!!!?!?!?!?!?!

I've never actually listened to EDTN tones but I'm 100% sure I'll enjoy
it. I've listened to American TDD tones by dialing local TDD numbers.

Dial 1-800-543-1586 and you'll hear the American TDD tones I am talking
about. This is an example of a TDD number used in the United States. I
want to hear the Swiss-equivalent of TDD.

What modulation scheme does EDTN use? FSK? QAM? Something else? What?

 

[nobody >]

Green Xenon [Radium] wrote:

I've never actually listened to EDTN tones but I'm 100% sure I'll enjoy
it. I've listened to American TDD tones by dialing local TDD numbers.

I'll bet the National Federation for the Blind (or some other agency )
is just thrilled by your tying up a line while you get your tonal rocks
off.

Why don't you get a pair of function generators and beat them together?
Who knows...you just might find your personal nirvana noise.

Now go back in your k00klair and leave us alone.

 

[Don Bowey]

On 9/28/07 1:28 PM, in article 46fd6158$0$7507$4c368faf@roadrunner.com,
"Green Xenon [Radium]" <glucegen1@excite.com> wrote:

IanB wrote:

On Fri, 28 Sep 2007 12:26:29 -0700, "Green Xenon [Radium]"
glucegen1@excite.com> wrote:

Specifically, where did you find
that EDTN is łEuropean Deaf Telephone Network˛?

I didn't. The "Network" bit was in brackets because I meant, but
forgot, to put a question mark in there as well.

So, IOW, you don't know for sure that EDTN equates to łEuropean Deaf
Telephone Network˛? I was afraid that would happen.

Whenever I've asked about EDTN [in relation to TDD], anyone who does
give an answer does not seem to know whether it is 100% correct. So my
suspicion was confirmed. !#%!$

Not trying to be a nuisance but Išm going crazy because of the
difficulty in answering my question.

Anyways, I am going to read the "TTE directive" and hopefully it will
answer my question.

And you need to know that not all terms are common to an industry, and may
be used by a single company in their literature..

 

[Green Xenon [Radium]]

Don Bowey wrote
http://groups.google.com/group/sci.electronics.basics/msg/f1a617da64d1eaa7 :

Google "tte directive"

The TTED is a piece of stinky human kakaa which stinks like the stinky
thick, foamy, tickly, itchy, hissy, sticky, terrifying, disgusting,
annoying diarrhea kakaa foam of a human who eats stale, fat-free cheddar
cheese, rotten lentils, fig newtons, and farty cauliflower along with
his/her kakaa.

http://www.google.com/search?hl=en&q=%22tte+directive%22+&btnG=Google+Search

Checked the 1st 10 pages. Absolutely nothing about EDTN!!!!

Checked EDTN with "tte directive" below

http://www.google.com/search?as_q=EDTN+&hl=en&num=10&btnG=Google+Search&as_epq=tte+directive&as_oq=&as_eq=edition&lr=lang_en&as_ft=i&as_filetype=&as_qdr=all&as_nlo=&as_nhi=&as_occt=any&as_dt=i&as_sitesearch=&as_rights=&safe=images

Absolutely nothing at all!!!!

I hate to be so rude and demanding but WTF is going on
here??????????!!!!!!!!!!!!?!?!?!?!?!?!?!

WTF don’t the websites about
Telecommunications-Terminal-Equipment-Directive say
anything about
EDTN????????????????!!!!!!!!!!!!!!!!!!!!!!?!?!?!?!?!?!?!?!?!?!

Before I actually did a search on "tte directive", I was extremely
optimistic and had a positive attitude that the search would tell me
what EDTN stands for [in relation to TTYs], the technical specs about
EDTN, and perhaps some EDTN numbers I could dial to listen to the
desirable tones. I was so f---------------king wrong!!!!!!!!!!!!!!!!!!!!
Now I am extremely upset and
disappointed!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

None of those sites told me what EDTN stands
for!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

I wish EDTN stood for “European Deaf Telephone Network” but it doesn’t.
My wish is way way way too good to ever be true. If EDTN stood for
“European Deaf Telephone Network”, then that would make life way too
easy!!!!!!!

If EDTN stood for “European Deaf Telephone Network”, then my search
http://www.google.com/search?hl=en&q=%22European+Deaf+Telephone+Network%22&btnG=Google+Search
would have yielded the results I am looking for.

If EDTN stood for “European Deaf Telephone Network”, then my search
http://www.google.com/search?hl=en&q=%22European+Deaf+Telephone+Network%22&btnG=Google+Search
would show a lot more information than just my previous posts!!!!!!!!!!!!!!

If EDTN stood for “European Deaf Telephone Network”, then my search
http://www.google.com/search?hl=en&q=%22European+Deaf+Telephone+Network%22&btnG=Google+Search
would describe how EDTN works and provide me with EDTN numbers which I
could dial so I could listen to EDTN tones from Switzerland!!!!!!!!!!

Unfortunately, reality -- being the sick sadistic f--k it is -- decides
otherwise. Sadly, EDTN does not stand for “European Deaf Telephone
Network” when relating to textphone terminology.

So just WTF does EDTN stand for?

Also, WTF can I find EDTN phone numbers so I can dial them and listen to
those frightening-yet-enjoyable EDTN tones from
Switzerland??????????????????!!!!!!!!!!!!!?!?!?!?!?!

I've never actually listened to EDTN tones but I'm 100% sure I'll enjoy
it. I've listened to American TDD tones by dialing local TDD numbers.

Dial 1-800-543-1586 and you'll hear the American TDD tones I am talking
about. This is an example of a TDD number used in the United States. I
want to hear the Swiss-equivalent of TDD.

What modulation scheme does EDTN use? FSK? QAM? Something else? What?

 

[JakTheHammer]

"John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote in message > On Sun, 24 Feb 2008 11:21:59 -0800 (PST), "M. Hamed"

mhs000@gmail.com> wrote:

In playing with my simple emitter follower circuit trying to figure
out why there's very faint output when connected to my 8 Ohm speakers,
I came upon some important realizations.

My circuit is a simple emitter follower with one transistor. The base
is biased to midpoint through a voltage divider and the input is
capacitively coupled. The output is also capacitively coupled through
a large capacitor to block DC. The emitter resistor is 5K.

I expected that with a large capacitor, even an 8 Ohm speaker would be
suitable to place the corner frequency of the high pass filter low
enough to pass audio frequencies and high enough to block DC. However
I was faced with two anomalies. Whenever I connect my speaker after
the capacitor, I hear a very faint and distorted sound. Whenever I
connect the speaker before the capacitor (the NPN's emitter), I get an
almost exact replica of the input (which is what the emitter follower
is supposed to do). Simulation confirmed this behavior but I was
puzzled with the result. Do I throw out of the window all I know about
high pass filters and frequency response. Also do I throw out the
importance of bias? Here we have a high pass filter that is not acting
like a high pass filter. And we have a low resistance emitter resistor
(after connecting the speaker in parallel with the 5K emitter
resistor) that should throw the bias point way off midpoint.

After playing with simulation for a while, and replacing the
transistor with equivalent circuit, etc, I hit upon one of my biggest
realizations in electronics (mind me if it's too obvious for you). The
models are correct so long as the transistor is ON and operating in
its linear region. In such a case the high pass filter will act nicely
and block DC and pass the audio signal. However, with such low
resistance, If the output to follow the input faithfully, huge current
will have to pass in the capacitor for the slightest negative output
voltage, and since the current in the emitter resistor (5 KOhm) is
very small compared, this current would have to follow in the
transistor in the opposite direction, so the transistor turns off.
That's my reasoning for why the transistor would turn off.

So now we have another mode of operation. Now it's another circuit.
It's not a high pass filter but a capacitor discharging through a
resistor. At a certain point the capacitor charge will be large enough
to have the transistor turn on only very briefly and the output
voltage change so little.

What caused my confusion is that in most electronic circuits, there
are transistors but often the circuit description doesn't tell if that
transistor will be ON all the time or not. Then analysis follows that
replaces caps with shorts at signal frequencies etc. But that's valid
only if the transistor stays on and hence acts as a linear device. I
wonder if circuit designers even with all their experiences and rules
of thumb take the extra step of analysis (or simulation) to make sure
the transistor is always operating in the linear region.


Good grief, of course we do. It's second nature.


If they do,
it's often not mentioned to us, less experienced people. In other
applications, such as rectifiers, the charging and discharging is
explicitly mentioned and used. This dual role of the capacitor always
puzzled me, when to think of it as a charging/discharging device, and
when to think in terms of frequency response and frequency dependent
impedance.

The other question was why connecting the speaker directly to the
output is OK. Why no blocking capacitor is needed? It turned out that
the small impedance shifts the DC bias point very close to ground, and
hence the output is a replica of the input but shifted up in DC level
just a few millivolts above ground, which seems to not alter the
speaker response much. That seems to be a problem if the gain is high
and clipping will start to happen as you move away from midpoint, but
when the gain is 1, no problem since the input signal is already a few
millivolts around 0.

A possibility here is that the speaker also responds to changes in
magnetic field and hence the DC component wouldn't matter, but i'm not
sure about that one.

I apologize for anyone who took the effort and went through my long
post. Am I right in my conclusions?

Thank you.

The emitter follower can only source current, not sink it. It can't
conduct less than zero current, so there's nothing but the wimpy 5K
resistor available to drive the speaker in the negative direction.

If you reduce the value of the emitter pulldown resistor, then you can
get a little more current into and out of the speaker in both
directions. But that's a losing game, which is why real power amps
usually have push-pull output stages.

Connecting the speaker directly to the emitter works at low levels,
but is inefficient and won't scale.

John

Correct Push-pull circuit works better, but for his situation, a single transistor amplification needs to use AF transformer on the collector side, with a pull-down emitter R of 150 ohms, to get more current into the transistor. Make sure to do this on a power transistor (>= .5a).

 

[Don Bowey]

"default" <default@defaulter.net> wrote in message news:nor8t39p6jh4f649nh51r29uk46pq0k41f@4ax.com...

On Sun, 9 Mar 2008 14:14:15 -0700 (PDT), mpm <mpmillard@aol.com>
wrote:

On Mar 9, 2:40?pm, default <defa...@defaulter.net> wrote:
I have an SD card in a camera. ?I want to use a controller to work the
camera. ?The construction of the camera doesn't lend itself to just
putting a scope on the SD card while it is working.

What I would like is some way to tell the controller that the picture
the camera just finished taking is in memory and it is OK to shut off
the camera. ?Is there some handshaking line that I could use to tell
when the card is being accessed and when it is just sitting there
waiting?
--

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One idea -- possibly not the best?

Can you just use the flash on the camera as an "input" to your
controller to know that the camera just took a picture, and then wait
a reasonable pre-determined period after that flash for the SD to do
it's thing? (In other words, set it up to use the flash, even if you
don't need it for exposure, and key off the flash with a
phototransistor.)

Note: I am assuming that the controller is not instructing the camera
to take the picture and that the camera does that by itself in
response to some other stimulus. Otherwise, this would be a rather
circular approach. -mpm

That would be self defeating but thanks for the suggestion. Just
charging the flash capacitor would sap more energy than running the
camera longer to allow for the pix to go into memory. I want to avoid
a modification that prevents the camera from functioning normally.

The controller is telling the camera to take a shot - the length of
time it takes to get the picture from the shutter click and safely
into memory varies, and the controller doesn't have a clue when it is
finished.
--


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Next time don't post your damn question any more ok Moron?