Re: Re: Hmevision ir transmitter

["Ian Davidson" <ian@xxxxxxx>]

OK I'm home

I think I've read the relevant messages. IF I've read them right then
HV
port a o/p is via a PNP which means it will source the o/p and give a
+volts
supply.

This lunch I built up a simple circuit details are here:

http://galeforce9.dnsalias.org/dsc0_0064.jpg

http://galeforce9.dnsalias.org/dsc0_0066.jpg

http://galeforce9.dnsalias.org/dsc0_0067.jpg

You only need the one transistor. It is ZTX651 I had on the bench at
work.
It will handling up to 2A and does not require any form of heatsink. It
is
an e-line transistor and has a very low on resistance. It will only
take
about 1mA of current to drive it from homevision. If the led's you use
are
20mA devices then each transistor will drive 100 of them. If this is
OTT
then the ZTX450 (IIRC) is half that at 1A.

The circuit is wired just to show it working ie the 10K resistor to the
base
is connected to the 5V rail to simulate a 5v o/p from HV.

If you drop me your address Andy I'll stick it in the post and you can
experiment with it. (It is no good to me !)


In answer to an earlier question you are correct that for current to flow
it
needs to complete a circuit. When voltage is applied to the base of a
transistor it flows through the base emitter junction of the transistor
to
ground.


I hope I've explained things ok, I'm not the best teacher, but if you
are
unsure just ask.

Again so as not to offend the list if ANYONE wants this topic off list
just
say and it will be.

Ian D




----- Original Message -----
From: "andy_powell_is" <ukha@xxxxxxx>
To: <ukha_d@xxxxxxx>
Sent: Friday, May 31, 2002 4:25 PM
Subject: [ukha_d] Re: Hmevision ir transmitter


>
> Go on, I dare you to show me the error.... :O
>
> Andy
>
>
> > Thats so clear, it wont work, with a short circuit across the
LEDs
> > Of course you knew that already !?
> > >
> > >
> > > A better diagram can now be found at:
> > >
> > > http://www.automated.it/homevision/HVIR2.jpg
> > >
> > > I used a freebie student version of Circuit Maker... :D
much
> clearer
> > > and nicer now :D :D
> > >
> > > Andy
>
>
>
>
> For more information: http://www.automatedhome.co.uk
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>

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