RE: Electronics help with IR TX-RX

["James Hoye" <james.hoye@xxxxxxx>]

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Where are you deriving the power (12v) for the TX board from?  Just
thinking
that the signal wire is going to be relative to Comfort's 0v - and if
you're
using another power source for the TX board.....

Just a thought - Keith will probably shed more light....

James H

> -----Original Message-----
> From: Graham Howe [mailto:graham@xxxxxxx]
> Sent: Tuesday, May 15, 2001 9:53 PM
> To: ukha_d@xxxxxxx
> Subject: RE: [ukha_d] Electronics help with IR TX-RX
>
>
> I have the Zener diode and resistor combination in place and that
works
> fine, what seems to be the problem is that the signal generated by
this
> (0.5V drop) is not interpreted properly by the transmitter unit when
the
> high voltage is applied. As I said the receiver bit seems to work
> OK (I can
> see the voltage drop on the signal wire) but the signal does give
> rise to a
> corresponding flashing of the LED (and IR LED) on the transmitter unit
if
> the higher voltage is involved.
>
> Graham
>
>  -----Original Message-----
> From: 	James Hoye [mailto:james.hoye@xxxxxxx]
> Sent:	15 May 2001 20:45
> To:	ukha_d@xxxxxxx
> Subject:	RE: [ukha_d] Electronics help with IR TX-RX
>
> This email was delivered to you by The Free Internet,
> a Business Online Group company. http://www.thefreeinternet.net
> ---------------------------------------------------------------
> The TSOPs work at 5v and as such need some sort of regulation -
> either using
> a 39p voltage regulator from M***** or the combination of a 5.1v
> Zener diode
> and a resistor.  Ian B's PCBs utilise the Zener/resistor - I'm sure he
can
> provide you with the circuit details.
>
> I have a couple of spare TSOPs, and I'm sure Keith has quite a few
left.
>
> James H
>
> > -----Original Message-----
> > From: Graham Howe [mailto:graham@xxxxxxx]
> > Sent: Tuesday, May 15, 2001 7:20 PM
> > To: UKHA List (E-mail)
> > Subject: [ukha_d] Electronics help with IR TX-RX
> >
> >
> > As many of you know, I eventually managed to put together some
> working IR
> > transmitters and receivers with help from several on the list and
> > despite my
> > non-existent electronics knowledge. However I now have a
> problem, the kit
> > works fine when I use a 12V battery and connect both TX and RX
> to it (with
> > an additional wire between them for the signal). I am currently
in the
> > process of installing Comfort and so drilled a little hole in one
of the
> > PIRs and inserted an IR RX unit. I connected the 12V and 0V from
> > the PIR to
> > the unit and used a spare wire in the CAT5 cable for the signal.
Then I
> > connected up the TX unit via Krone blocks and patch panel and it
didn't
> > work. After I finished cursing myself for not testing the set up
before
> > gluing the RX inside the PIR I started to investigate. After
> much probing
> > with a voltmeter, I discovered that the 12V output from Comfort
> > was actually
> > 13.8V and that when fed with this voltage the kit wouldn't work,
> > in fact the
> > TS1308 (is that the right code? If not it is the things Keith
> was selling)
> > seemed to die after a while at this voltage (I now have 2 dead
> > ones). I then
> > tried having just the RX unit fed by Comfort and the TX fed by
> > the battery,
> > this didn't work either, even though I could see the 0.5V drop in
the
> > trigger wire when IR was received. At this point I started
> thinking that I
> > was well and truly out of my depth, so I started guessing what
might be
> > wrong. Here are my thoughts:
> >
> > The RX unit will operate correctly for at least a limited time
when
> > connected to the 13.8V, the trigger wire shows 5V which drops
> to 4.5V when
> > IR is received.
> >
> > The TX unit does not appear to like the higher voltage at all and
> > certainly
> > doesn't react correctly to the trigger when the higher voltage
> is applied
> > (could it be that the 0.5V drop is no longer sufficient to do
> the 'magic'.
> >
> > Both a RX and a TX unit appear to have been killed during my
> experiments,
> > possibly as a result of the high voltage.
> >
> > It seems I have two options, either use an alternative power
> > supply that is
> > closer to 12V and therefore put up with less convenient wiring
inside my
> > PIRs. Or use some sort of electronic trickery (possibly a
resistor?) to
> > reduce the voltage supplied from Comfort (after all the Comfort
> > outputs are
> > labeled 12V).
> >
> > Please can one of you electronic geniuses give me some advice,
> > with the DDAR
> > price increase this is turning out to be a very unsuccessful day!
> >
> > Graham
> >
> >
> >
> >
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> >
> >
> >
>
>
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