RE: Re: Idea for IR zoning with HV

["Keith Doxey" <lists.diyha@xxxxxxx>]

Hi Andy,

simple explanation coming up.....

The IR LED requires power to emit infra red.

This power is normally supplied from the IR out jack.

There are two ways of supplying this power....

1. Switching the +5v supply and connecting the LED between that and a
permanent ground.
2. Supplying a permanent +5v supply and switching the ground.

Either method will turn the LED Off and On.


HomeVision used method 1 where the negative side of the LED is connected
to
a pemanent ground and everytime the +5v is switched to the IR out jack
the
LED will light.

If you were to break the -ve connection the LED will not light as below

IR Out ________LED1 _______/ __________ Ground
         
                     
          ____LED2 _______/
____

             IR
LED's     Switches

With the switches open as above then no matter what you send out of the
IR
Out none of the LEDS will light

IR Out ________LED1 _______/ __________ Ground
         
                     
          ____LED2
_____________

             IR
LED's     Switches

With the switched as above LED2 will emit IR but not LED1 therefore the
IR
has been zoned. This is what people were wanting to use relays for but
they
are not required.

HomeVision PortA has "Open Collector" outputs which are simply a
transistor
connected to ground. If it helps, then think of it as a solid state
equivelent of the switch shown above. Because of this it can perform
the
same function. You simply wire the Positive side of all teh LED's to the
tip
of the  3.5mm jack plug but instead of connecting the Negative side of
the
LED's to the sleeve of the jack you return them to individual pins of
PortA.

To build a suitable connecting block get a 3.5mm jack plug and upto 8 x
3.5mm jack sockets.

>From the tip (centre pin) of the 3.5mm plug connect it to the tip of
every
3.5mm jack socket via an individual 100 ohm resistor. Run 8 wires from
the
sleeve terminal of each socket back to an individual pin on PortA.

you can then use your homemade connecting block as 8 Zones of IR
providing
you enable the correct socket prior to sending the IR.

You just need to include an extra line  or two in your schedule to
enable/disable the appropriate emitter.


Keith

www.diyha.co.uk
www.kat5.tv


-----Original Message-----
From: andy_powell_is [mailto:ukha@xxxxxxx]
Sent: 28 April 2002 13:15
To: ukha_d@xxxxxxx
Subject: [ukha_d] Re: Idea for IR zoning with HV



I really really wish I understood this... it seems like a simple
solution that will work... but I just don;t understand it :(

Anyone fancy building something like this for me ... pretty please?
with idiot proof docs.. :D

Andy

--- In ukha_d@y..., "Keith Doxey" <lists.diyha@b...>
wrote:
> You dont actually need ANYTHING to Zone IR on Homevision.
>
> The 3.5mm jack has the tip connected to SWITCHED +5v which is the
modulated
> IR output.
> The sleeve of the jack is permanently connected to ground.
>
> PORT A is an open collector driver which GROUNDS the pins of port
A.
>
> If you wire like this you have IR
>
>
> 3.5mm
> Tip
----------------------------------------------------------------
--------
> ----------------------
>                      
                   
                     
>
                    
>                     
R                  
R                    
R
>
R                  
R
>                      
                   
                     
>
                    
>                     
E                  
E                   
E
>
E                  
E
>                      
                   
                     
>
                    
>                     
A1               
A2                   
A3
>
A4                 
A5 ETC
>
> where R is a series resistor of about 100 ohms, E is the IR
emitter, A(x) is
> the port A pin
>
> Before you send an IR command you just set the required pin of
port
A to low
> (remember the logic is inverted for PortA) and away you go.
> Keith
>
> www.diyha.co.uk
> www.kat5.tv




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