RE: Re: Hmevision ir transmitter

["Ian B" <Ian@xxxxxxx>]

Good catch on the design. It was late last night after a fun time with
the
new baby.

I agree about the recent post of messages being confusing to say the
least.
Your design is better than mine and I have set it up as a pdf for
simplicity
and recording at my end. I am still learning after all.

Both of the designs achieve the same aim of zoned output controlled by
one
of HV ports. I thought some of the previous discussion was going off track
a
bit and all that negative logic was horrid.

As soon as I find out the path on the web server to my web site I will
post
the pdf's there but in the mean time here is another apology and another
4k
attachment. All down to playing primary domain controller removal and
it
deleted my accounts as well - dohh.

Andy - sorry if all this is confusing and shout if anything (apart from
everything, oh well, that as well) is unclear.

A quick lesson on transistors!!
These other transistors we are talking about with the arrow going into
the
base rather that out of it operate in a different way. You can think of
the
ones where the arrow goes out of the base BC182 etc. as having the
turning
on power flow into the base and out of the emitter. The other ones like
a
BC327 etc. have the turning on power flow into the collector and OUT of
the
base. This is very simplistic and of course current is negligible when
referring to the base. In both types the main flow of current when the
device is active is from collector to base. Hopefully this makes sense
(and
I am correct).

Ian B

>-----Original Message-----
>From: Ian Davidson [mailto:ian@xxxxxxx]
>Sent: 01 June 2002 09:32
>To: ukha_d@xxxxxxx
>Subject: Re: [ukha_d] Re: Hmevision ir transmitter
>
>
>Hi Ian B
>
>If you wish to do it the way you suggest an easier circuit would be
>
>http://galeforce9.dnsalias.org/dsc0_0069.jpg
>
>A few less components and current draw off the ports of HV still
>well within
>the limits.
>
>As I've said I don't have HV (maybe one day!) but if the members that
do
>have it and require the IR say which port they would prefer to use and
the
>maximum ratings they would want to control then I'm sure we could
design a
>circuit with minimum components that most people even with minimum
>electronics experience could build.
>
>At the moment things keep changing so I think any designs should be
shelved
>until a common goal is reached as to what is required, if not the
poor
>people trying to understand basic electronics from that last batch
of
>messages will be frightened off for life !!!
>
>Ian D
>
>----- Original Message -----
>From: "Ian B" <Ian@xxxxxxx>
>To: <ukha_d@xxxxxxx>
>Sent: Saturday, June 01, 2002 12:46 AM
>Subject: RE: [ukha_d] Re: Hmevision ir transmitter
>
>
>> Your circuit looks like I had in mind back in year dot. I have sat
down
>and
>> had a think about this and we have been leading you up the garden
path a
>> bit. Fun trip though wasn't it. Anyway, here are my
thoughts..........
>>
>> I have attached (for my sins) a very small pdf with the circuit
(not
>quite)
>> as I saw it in my minds eye.  Things have changed a bit and
the TR1 codes
>> etc. no longer refer to the same transistors so pay attention.
After some
>> (considerable) thought I figure the best way to do this is use
Port C in
>> OUTPUT mode. According to the specs it can drive TTL and CMOS.
This means
>> LED's so enough current for us.
>>
>> In off state PortC must be all zeros and we don't care what the IR
out is
>> doing. In this state TR2 is not conducting so the LED's are never
on.
>>
>> Right, from the left ($^%!) we have a pull up resistor connecting
to a
>> tranny TR1. When HV transmits IR the base is pulled low and the
tranny
>stops
>> conducting. I assume here that HV switches the ground. This in
turn sends
>> the voltage through TR2 high. This is where the clever zoning bit
is. If
>> PortC pin x is high it drives the tranny TR2 base and the voltage
reaches
>> TR3 - zone ON. If however the PortC pin x was low the voltage
would never
>> reach TR3 and nothing happens. As soon as the voltage reaches TR3
it
>> conducts and the LED's come on! Voila...... Obviously the LED's on
the
>right
>> would be as many as you want i.e. 8 in your case.
>>
>> Well, that's the theory anyway.
>>
>> There may be a better way round this but it is late and I am
tired
>(excuses
>> excuses).
>>
>> I hope this is helpful and that I have got it somewhere near
correct.
>>
>> Off for a midnight snack, have fun. Let me know if the diagram and
text
>are
>> rubbish.
>>
>> Ian B
>>
>> p.s. you owe me one for making me think!! ;-))
>>
>> >-----Original Message-----
>> >From: andy_powell_is [mailto:ukha@xxxxxxx]
>> >Sent: 31 May 2002 20:25
>> >To: ukha_d@xxxxxxx
>> >Subject: [ukha_d] Re: Hmevision ir transmitter
>> >
>> >
>> >
>> >Ok, I'll try again.... (this is an abridged version!)
>> >
>> >I've got the original circuit working.. it was the 2N2222 that
was..
>> >err dead.. replaced it and it's all ok now...
>> >
>> >The circuit now consists of the diagram at
>> >http://www.automated.it/homevision/HVIR2.jpg
but with the bit that
>> >says Homevision port removed...
>> >
>> >
>> >> I think I've read the relevant messages. IF I've read
them right
>> >
>> >There was a sudden rush of them, mainly due to my lack of
>> >intelligence :P
>> >
>> >> port a o/p is via a PNP which means it will source the
o/p and give
>> >a +volts
>> >> supply.
>> >
>> >I've used the phrase before, and I'm going to use it again,
err,
>> >chicken soup...
>> >
>> >> This lunch I built up a simple circuit details are
here:
>> >> http://galeforce9.dnsalias.org/dsc0_0064.jpg
>> >
>> >Thanks, I've saved them for reference...
>> >
>> >> You only need the one transistor. It is ZTX651 I had on
the bench
>> >at work.
>> >
>> >Awwww, I have a big bag of 2N2222's and BC182's :(
>> >
>> >
>> >> It will handling up to 2A and does not require any form
of
>> >heatsink. It is
>> >
>> >I've put a 1k resistor in from the power supply to the
collector of
>> >the first transistor and according to the Circuit maker I'm
pulling
>> >2.995ma (the 1k resistor appears to drop the current from
32.5ma to
>> >2.995ma, apparently)... is that a problem? am I going to
upset
>> >homevision by putting that resistor in there? it still works
on the
>> >breadboard...
>> >
>> >Bearing in mind that this is only 1/8 of the circuit, if I add
7 more
>> >am I going to pull too much current?
>> >
>> >> 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
>> >
>> >Phoaaaarrrrr!! 8 zones of 100 emitters :P
>> >
>> >> 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.
>> >
>> >So the HV port A supplies +5v too?? This is the bit I'm really
unsure
>> >of... should I connect the base of the first emitter to
Homevisions A
>> >ports via a 10k resistor (one for each A port ie one for A1,
one for
>> >A2..etc)?
>> >
>> >
>> >> 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 !)
>> >
>> >I'll email it privately... :D
>> >
>> >
>> >>
>> >> 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.
>> >
>> >You've lost me with this. Where is this? is it that it flows
(in the
>> >circuit at the url above) to the second transistor via it's
emitter
>> >and off to the seond and then to the emitter of that and hence
to
>> >ground?
>> >
>> >
>> >> I hope I've explained things ok, I'm not the best
teacher, but if
>> >you are
>> >> unsure just ask.
>> >
>> >You're doing pretty well if you ask me...
>> >
>> >> Again so as not to offend the list if ANYONE wants this
topic off
>> >list just
>> >> say and it will be.
>> >
>> >I did ask and the suggestion was that quite a few people
are
>> >interested, not only that but that this was one of the few on
topic
>> >threads... :O
>> >
>> >Thanks for all your help
>> >
>> >
>> >Andy
>> >
>> >
>> >
>> >For more information: http://www.automatedhome.co.uk
>> >Post message: ukha_d@xxxxxxx
>> >Subscribe:  ukha_d-subscribe@xxxxxxx
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>> >List owner:  ukha_d-owner@xxxxxxx
>> >
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http://docs.yahoo.com/info/terms/
> >
> >
> >
>
>
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>




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HVIR.pdf