Re: Hmevision ir transmitter

["andy_powell_is" <ukha@xxxxxxx>]

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



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