AVR-Chat

this seems to wire an (infrared) LED to an output bit. And a photosensitive diode to the input port of a different micro. Well, this is OK if (a) the receiver diode is never near light/sunlight and (b) the intended range is very short. A practical system would not use a simple diode for receiving; it would use a $3.00 IR receiver module and the data would be modulated on a carrier like 38KHz. This is how TV remotes work. The receiver module has a bandpass filter yielding a reasonable signal-to-noise. The data coding varies but the "RC5" pseudo-standard is popular.

----- Original Message -----

I think you guys miss the point of single LED wireless coms. It is only 
intended for a very short distance such as when an operator stands in 
front of the instrument etc. Sure, I've used the IR receiver's before 
but that is another kettle of fish altogether and not really suitable 
for UART coms, especially at higher baud rates. BTW, the ambient light 
conditions have to be fairly bright before this circuit may need some 
simple shielding such as recessing the LED.

The circuit notation is obvious if you have ever wired a circuit up 
before, otherwise you may find it a bit terse. The "~~ 10K ~~" means a 
10K resistor with the connections on either end, BASE means connection 
to the BASE of the transistor etc etc. What else would BASE mean? It is 
possible to use ASCII art to draw the circuit, but I always find that 
laborious, a bit like illuminating manuscripts.

Anyway, you guys can be academic about it all and compare apples and 
oranges all day long if you like. I'll keep on doing what an engineer 
does best .... being practical.

*Peter*

stevech@san.rr.com wrote:

>this seems to wire an (infrared) LED to an output bit. And a photosensitive 
>diode to the input port of a different micro. Well, this is OK if (a) the 
>receiver diode is never near light/sunlight and (b) the intended range is very 
>short. A practical system would not use a simple diode for receiving; it would 
>use a $3.00 IR receiver module and the data would be modulated on a carrier like 
>38KHz. This is how TV remotes work. The receiver module has a bandpass filter 
>yielding a reasonable signal-to-noise. The data coding varies but the "RC5" 
>pseudo-standard is popular.
>
>----- Original Message -----
>
>From: Thomas Keller <tkeller1@neb.rr.com>
>
>Date: Monday, October 10, 2005 10:39 am
>
>Subject: Re: [AVR-Chat] Re: Intercom using single LED
>
> > On Mon, 2005-10-10 at 12:28 +1000, Peter Jakacki wrote:
> > > I call it my 20 cent wireless coms.
> > > Basic circuit connections:-
> > > GND ~~ [LED- LED+] ~~ 10K ~~ BASE
> > > LED+] ~~ 100R ~~ OUTPUT PORT ( or use a PNP for
> > more
> > > drive or if using a UART )
> > > VDD ~~ PULL-UP ~~ COLLECTOR ~~ INPUT PORT
> > > GND ~~ EMITTER
> >
> >
> > Uh...call me dense, but this means nothing to me. Could you
> > explainyour notation, please?
> >
> >
> > Tom
>
>  
>

On Tue, 2005-10-11 at 08:23 +1000, Peter Jakacki wrote:
> The circuit notation is obvious if you have ever wired a circuit up 
> before, otherwise you may find it a bit terse. The "~~ 10K ~~" means a
> 10K resistor with the connections on either end, BASE means connection
> to the BASE of the transistor etc etc. What else would BASE mean? It
> is possible to use ASCII art to draw the circuit, but I always find
> that laborious, a bit like illuminating manuscripts.

   Well, with that information, I can now make sense of the description,
though I must say in over 35 years of doing electronics as both a
hobyist and a professional, I have never seen a circuit described in
this way.

   Also, what does 100R indicate?

> Anyway, you guys can be academic about it all and compare apples and 
> oranges all day long if you like. I'll keep on doing what an engineer 
> does best .... being practical.

   Since you didn't specify the environment of the application, their
comments were completely appropriate.   In most REAL WORLD applications,
the system you are describing would be, at best, unreliable.  Engineers,
being practical, attempt to engineer in enough head room to keep the
system woirking under adverse conditions, actually...*THAT* is what
"engineers" do.  

Tom

Thomas Keller wrote:
>    Also, what does 100R indicate?

Tell me that's a trick question!

In case it's not, here's the first thing Google picked up!

   http://www.lalena.com/audio/electronics/color/

35 years huh?

Peter








.

In the US, history says a resistor less than 1000 ohms is written as just a
number. No "R". I suppose you can find examples in the US such as 1R5 for
1.5 ohms; not sure.

Shall we move on to British "earth" versus US "ground"?

-----Original Message-----
From: AVR-Chat@yahoogroups.com [mailto:AVR-Chat@yahoogroups.com] On Behalf
Of Peter Gargano
Sent: Monday, October 10, 2005 7:36 PM
To: AVR-Chat@yahoogroups.com
Subject: Re: [AVR-Chat] Re: Intercom using single LED

Thomas Keller wrote:
>    Also, what does 100R indicate?

Tell me that's a trick question!

In case it's not, here's the first thing Google picked up!

   http://www.lalena.com/audio/electronics/color/

35 years huh?

Peter








.



 
Yahoo! Groups Links

At 03:14 PM 11/10/2005, you wrote:
>Shall we move on to British "earth" versus US "ground"?

I believe 100R or whatever is an international standard
and has been so for a long time (20 years??)

Regards

John Samperi

******************************************************
                         Ampertronics Pty. Ltd.
   11 Brokenwood Place Baulkham Hills, NSW 2153 AUSTRALIA
          Tel. (02) 9674-6495       Fax (02) 9674-8745
                Email: samperi@ampertronics.com.au
                  Website  http://www.ampertronics.com.au
* Electronic Design   * Custom Products   * Contract Assembly
******************************************************

On Tue, 2005-10-11 at 12:35 +1000, Peter Gargano wrote:
> Thomas Keller wrote:
> >    Also, what does 100R indicate?
> Tell me that's a trick question!
> In case it's not, here's the first thing Google picked up!
>  35 years, huh?

  I've always been confrontational, but you really take the cake, Peter!

  "R" is the color red, so what is the 100 supposed to indicate? I've
never before seen color used in a circuit description. There is no
common electrical unit I am aware of that is designated by an "R" in
that manner.  Is this more of your view of "being practical?"

  I apologize to the members of the list, but this guy's attitude is
beginning to really rankle on me. I did manage to control myself to the
extent of watching my language, but it wasnt easy!

Tom

On Tue, 2005-10-11 at 16:01 +1000, John Samperi wrote:
> At 03:14 PM 11/10/2005, you wrote:
> >Shall we move on to British "earth" versus US "ground"?
> I believe 100R or whatever is an international standard
> and has been so for a long time (20 years??)

   Ok that is possible, and makes sense to me.   I spent the better part
of the past 20 years NOT being ionvolved directly in electronics, so I
may have missed something.   Back in "the day," resistance values on
schematics were indicated by either just a number (e.g., 10,000) or by a
number followed by a lower case omega.  On rare occasions, some
drafts-people would indicate with the number and the word "ohms."

   I would like to note that I was not challanging Peter on that issue,
I honestly didn't understant the notation, just as I didn't understand
his schematic notation.

Tom

Thomas Keller wrote:

> On Tue, 2005-10-11 at 16:01 +1000, John Samperi wrote:
> 
>>At 03:14 PM 11/10/2005, you wrote:
>>
>>>Shall we move on to British "earth" versus US "ground"?
>>
>>I believe 100R or whatever is an international standard
>>and has been so for a long time (20 years??)
> 
> 
>    Ok that is possible, and makes sense to me.   I spent the better part
> of the past 20 years NOT being ionvolved directly in electronics, so I
> may have missed something.   Back in "the day," resistance values on
> schematics were indicated by either just a number (e.g., 10,000) or by a
> number followed by a lower case omega.  On rare occasions, some
> drafts-people would indicate with the number and the word "ohms."
> 
>    I would like to note that I was not challanging Peter on that issue,
> I honestly didn't understant the notation, just as I didn't understand
> his schematic notation.
> 
> Tom

This is not so much a "British" thing as a "German" thing, with the Din 
and ISO standards for drafting, all decimal points are replaced by a 
letter indicating the decimal point eg a 1.2K resistor is 1K2, bellow 1K 
we use an R as it is easier to draft than an omega.

I agree that it different, but it is just what you are used to.

Regards,

Kat.


-- 
---------------------------------------------------------------
K.A.Q. Electronics	Website: www.kaqelectronics.dyndns.org
IM: Yahoo: PinkyDwaggy  MSN: katinka@kaqelectronics.dyndns.org
For Everything Electronics     Phone: 0419 923 731
---------------------------------------------------------------	


-- 
No virus found in this outgoing message.
Checked by AVG Anti-Virus.
Version: 7.0.344 / Virus Database: 267.11.14/128 - Release Date: 10/10/2005

>   "R" is the color red, so what is the 100 supposed to indicate? I've
> never before seen color used in a circuit description. There is no
> common electrical unit I am aware of that is designated by an "R" in
> that manner.  Is this more of your view of "being practical?"

The link that Peter posted
<http://www.lalena.com/audio/electronics/color/> explains the use of R
quite well. The suffix M means x 10 to the power 6. The suffix K means
x 10 to the power 3, and the suffix R means x 10 to the power zero.

So, 100K means 100,000 ohms. 100R means 100 ohms.

The R is often used in place of a decimal point, since the decimal
point is so hard to see, especially on small surface mount devices.

6R8 means 6.8 ohms.

With surface mount devices (at least the ones I've seen), they use the
R and not the K or M. So 10K would be written as 103.

--
Dave Hylands
Vancouver, BC, Canada
http://www.DaveHylands.com/

I have seen this notation used on quite a few schematics lately, most 
coming from Germany or Japan.  I figured it meant just what you noted, 
Kat.  In the same drawings I've seen notations like 2R7 and 0R27, etc.

Zack

On Tue, 11 Oct 2005, Kathy Quinlan wrote:

> 
> This is not so much a "British" thing as a "German" thing, with the Din
> and ISO standards for drafting, all decimal points are replaced by a
> letter indicating the decimal point eg a 1.2K resistor is 1K2, bellow 1K
> we use an R as it is easier to draft than an omega.
> 
> I agree that it different, but it is just what you are used to.
> 
> Regards,
> 
> Kat.
>

On Tue, 2005-10-11 at 08:54 -0700, Dave Hylands wrote:
> >   "R" is the color red, so what is the 100 supposed to indicate?
> I've never before seen color used in a circuit description. There is
> no common electrical unit I am aware of that is designated by an "R"
> in that manner.  Is this more of your view of "being practical?"
> The link that Peter posted
> <http://www.lalena.com/audio/electronics/color/> explains the use of R
> quite well. The suffix M means x 10 to the power 6. The suffix K means
> x 10 to the power 3, and the suffix R means x 10 to the power zero.

  Ah!   My error.   When I saw the color code chart on that site, I
looked no further, as I was considerably irritated/  Maybe I need to
calm down a bit, eh?  *smile*

   This notation is decidedly new to me. I have never seen it or heard
of it before.  I guess being out of the game for 20 years can really
foul you up.

Tom

Hi Tom,

Don't get us Peters mixed up now! (look at the column that says "Sender") :)

I could of attached a nice little schematic but that would of been 
filtered out and so we are left
with either a link to a webpage or inline ascii schematics. I'm only 
trying to be helpful but I really didn't want to spend any more time on 
supplying the details than I did. Usually I attempt some ascii 
schematics and this time it seemed ok just to supply it in a totally 
non-standard pseudo-netlist form.

Also, the circuit works well for it's intended use and allows firmware 
uploads/data downloads etc without having to have an external connector, 
which sometimes is not possible or desirable. Sometimes this circuit 
just sits on a PCB internal to the equipment, accessible only by 
technicians when there is some diagnostics or firmware uploads to do.

Finally, there is nothing safety-critical about the use of this coms 
circuit. Nobody is trying to reliably control any lump of equipment, big 
or small, with the lousy stream of photons emanating from this circuit. 
Practical does not mean all-encompassing, if a clothes peg keeps your 
washing on the line then it is practical for that purpose.

:) keep smiling

*Peter*



Thomas Keller wrote:

>On Tue, 2005-10-11 at 16:01 +1000, John Samperi wrote:
>  
>
>>At 03:14 PM 11/10/2005, you wrote:
>>    
>>
>>>Shall we move on to British "earth" versus US "ground"?
>>>      
>>>
>>I believe 100R or whatever is an international standard
>>and has been so for a long time (20 years??)
>>    
>>
>
>   Ok that is possible, and makes sense to me.   I spent the better part
>of the past 20 years NOT being ionvolved directly in electronics, so I
>may have missed something.   Back in "the day," resistance values on
>schematics were indicated by either just a number (e.g., 10,000) or by a
>number followed by a lower case omega.  On rare occasions, some
>drafts-people would indicate with the number and the word "ohms."
>
>   I would like to note that I was not challanging Peter on that issue,
>I honestly didn't understant the notation, just as I didn't understand
>his schematic notation.
>
>Tom
>

Kathy Quinlan wrote:
> Thomas Keller wrote:

[===]

>>   I would like to note that I was not challanging Peter on that issue,
>>I honestly didn't understant the notation, just as I didn't understand
>>his schematic notation.
>>
>>Tom
> 
> 
> This is not so much a "British" thing as a "German" thing, with the Din 
> and ISO standards for drafting, all decimal points are replaced by a 
> letter indicating the decimal point eg a 1.2K resistor is 1K2, bellow 1K 
> we use an R as it is easier to draft than an omega.

Also, omega is not found in most character sets.  I for one would be 
happy to at least see lower case mu, pi, and the uppercase omega in any 
of the standard character sets since I use those symbols all the time in 
my (technical) writing.
> 
> I agree that it different, but it is just what you are used to.

Actually, I find it such a sensible form of notation that I now use it 
myself (I'm a Yank)  ;-)

An OT question of my own:  On European drawings, they use a certain very 
legible font-face when labelling thier drawings.  I'm wondering if that 
font isn't also a DIN/ISO specification as well, and if so, what is it.

> Regards,
> 
> Kat.


erikc

erikc wrote:
> Kathy Quinlan wrote:
> 
>>Thomas Keller wrote:
> 
> [===]
> 
>>>  I would like to note that I was not challanging Peter on that issue,
>>>I honestly didn't understant the notation, just as I didn't understand
>>>his schematic notation.
>>>
>>>Tom
>>
>>This is not so much a "British" thing as a "German" thing, with the Din 
>>and ISO standards for drafting, all decimal points are replaced by a 
>>letter indicating the decimal point eg a 1.2K resistor is 1K2, bellow 1K 
>>we use an R as it is easier to draft than an omega.
> 
> Also, omega is not found in most character sets.  I for one would be 
> happy to at least see lower case mu, pi, and the uppercase omega in any 
> of the standard character sets since I use those symbols all the time in 
> my (technical) writing.

Switch to a unicode locale and configure your keyboard to put the greek
symbols into the second group (using xkb in linux).

>>I agree that it different, but it is just what you are used to.
> 
> Actually, I find it such a sensible form of notation that I now use it 
> myself (I'm a Yank)  ;-)
> 
> An OT question of my own:  On European drawings, they use a certain very 
> legible font-face when labelling thier drawings.  I'm wondering if that 
> font isn't also a DIN/ISO specification as well, and if so, what is it.