Re: Re: Hmevision ir transmitter

["Ian Davidson" <ian@xxxxxxx>]

Hi Andy

Ok no problems, we will get you sorted.

Firstly I do not have homevision and I could do with knowing the
following
if you or others on the list know or could point me to the tech spec:-

firstly what sort of o/p does HV produce, is it open collector ?

Does it have any internal pull up resistors ?

If it does have internal pullups then your circuit may well function but
not
by just fitting a switch to the base of TR1.

Do you need the LED's on when the port o/p is low or when it is high ?

If we can find out these details then I'll try to explain how to test it,
or
if not what to change. If all else fails I'll build you a single
channel
unit and then all you would need is to copy it.

Not sure if any one else on the list needs the info but if not your
more
that welcome to take the mails off list and send to me direct, I'll leave
it
up to you.

Ian D



----- Original Message -----
From: "andy_powell_is" <ukha@xxxxxxx>
To: <ukha_d@xxxxxxx>
Sent: Thursday, May 30, 2002 9:04 PM
Subject: [ukha_d] Re: Hmevision ir transmitter


>
> Ian,
>
> Thanks for the reply, I should say that I'm just starting out in
> electronics so you'll need to dumb - down any advice :P ...
>
> if you look at:
>
> http://groups.yahoo.com/group/ukha_d/files/Transistor.bmp
>
> You'll basically see the circuit. The general idea is to take the
IR
> pulse (which appears to be +5v for on and 0v for off) and output
to
> multiple IR LEDs. The obvious things are that:
>
> a) I don't want to go near Homevision until it's tested
> b) the current draw from homevision should be as little as
possible.
>
> In the end I'm aiming for 8 zones of IR with 8 outputs (3.5mm mono
> jacks into which emmiters can be plugged) for each zone plus 1 LED
as
> an indicator for each zone...
>
> Hope this explains a little of what I'm hoping to achieve...
>
> Thanks again,
>
> Andy
>
>
>
>
> --- In ukha_d@y..., "Ian Davidson" <ian@g...>
wrote:
> > Hi
> >
> > I've not been following this thread but I have just drawn out
the
> circuit
> > you described.
> >
> > The BC182 will never conduct because it never has any voltage
on
> it. i.e. it
> > is either not connected or connect to ground via the switch.
The
> bc182 is an
> > NPN transistor and requires at least 0.7v between b/e junction
to
> conduct.
> > If you add a pull up resistor between the base and vcc it
should
> work but
> > you will need a value high enough to prevent exceeding the
base
> current. If
> > you tell me exactly what you want to achieve I'll try to be
more
> helpful.
> >
> > Ian D
> >
> > ----- Original Message -----
> > From: "andy_powell_is" <ukha@b...>
> > To: <ukha_d@y...>
> > Sent: Thursday, May 30, 2002 7:59 PM
> > Subject: [ukha_d] Re: Hmevision ir transmitter
> >
> >
> > >
> > > Ian,
> > >
> > > I'm actually stubling at the first hurdle here...
> > >
> > > I have :
> > >
> > > One one breadboard with a 5v supply a BC182, C is connected
to +5v
> > > via a resistor, B is connected to Ground (via a push switch)
and
> E is
> > > connected to the B of a 2N2222 on another breadboard with
5v
> supply
> > > (spearate from the first one). The C of the 2N2222 is
connected
> to 2
> > > LED's in series with a 220ohm resistor and the E is
connected to
> the
> > > ground of the supply on this board.
> > >
> > > I expected the LED's to light up - guess what? It does
nothing :(
> > >
> > > Any ideas???
> > >
> > > I thought it was the circuit I'd drawn (uploaded to the
files
> area)
> > > before...
> > >
> > > Andy :(
> > >
> > >
> > >
> > >
> > >
> > > --- In ukha_d@y..., "Ian B" <Ian@M...>
wrote:
> > > >
> > > > > I noticed that you said you were using 3 port
pins, which
> sounds
> > > > > better than using 8...
> > > >
> > > > Andy
> > > >
> > > > I think Frank has built this round a 3 to 8 decoder
which means
> > > only one
> > > > zone could be active at any on time. Using all 8 pins
of port A
> > > gives you
> > > > any combination you want simultaneously.
> > > >
> > > > Ian B
> > >
> > >
> > >
> > > For more information: http://www.automatedhome.co.uk
> > > Post message: ukha_d@xxxxxxx
> > > Subscribe:  ukha_d-subscribe@xxxxxxx
> > > Unsubscribe:  ukha_d-unsubscribe@xxxxxxx
> > > List owner:  ukha_d-owner@xxxxxxx
> > >
> > > Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
> > >
> > >
> > >
>
>
>
> For more information: http://www.automatedhome.co.uk
> Post message: ukha_d@xxxxxxx
> Subscribe:  ukha_d-subscribe@xxxxxxx
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>
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>
>
>




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