Re: Re: Hmevision ir transmitter

["Ian Davidson" <ian@xxxxxxx>]

Ok Andy here goes....

If the circuit is as the diagram in the files area then by biasing the
first
transistor the led's should light.

To try this connect say a 10K Ohm resistor from the +5V rail to the base
of
the BC182.(TR1)

If you think of this as a switch which will now turn on allowing the
voltage
to reach the base of TR2. This will then do the same. So current will
then
flow through the LED's through TR2 to complete the circuit.

Let me know if that works ?

If it does we may be able to simplify this a little before you build
the
rest up.

Ian D



----- Original Message -----
From: "andy_powell_is" <ukha@xxxxxxx>
To: <ukha_d@xxxxxxx>
Sent: Thursday, May 30, 2002 10:09 PM
Subject: [ukha_d] Re: Hmevision ir transmitter


> --- In ukha_d@y..., "Ian Davidson" <ian@g...>
wrote:
> > Hi Andy
> >
> > Ok no problems, we will get you sorted.
>
> Thanks Ian :D
>
>
> > 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
?
>
> Yes, "Port A of Homevision provides open collector
terminals"
>
>
> > 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.
>
> I don't know the answer to this one :( but looking at
> http://www.csi3.com/hv_p2.htm near
the bottom, there is a table. For
> the ports B and C it says pulled up, for port A it does not
mention
> it ... at a guess, based on that I'd say no... but I don't know
for
> sure...
>
>
> > Do you need the LED's on when the port o/p is low or when it
is
> high ?
>
> From what I remember Keith was saying that you set the port low to
> complete the circuit where +5 is provided by the IR jack and the
port
> on Homevision provides the ground. So, the LED should come on when
> it's low (and an IR pulse is sent)
>
> >
> > 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.
>
> That would be nice, but it would be better for my skills if I
could
> work with you to get the final result. If all else fails I'll
gladly
> take you up on the offer..
>
>
> > 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.
>
> I think that if this ever gets to work :P quite a few people would
be
> interested in it.... so perhaps for the moment we should keep it
on
> list...
>
> Thanks again for your replies..
>
> Andy
>
>
>
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>




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