AVR-Chat

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
>
>  
>