RE: RE: RE: Dr. John's Lighting System

[Keith Doxey <keith.doxey@xxxxxxx>]

Hi John,

>What processor are you going to use ?

To start with it will be 16C84 or 16F84 but I might have to move to
other processors if I run out of I/O pins.

>What network did you have in mind ?

RS485

>Had you any protocol in mind ?

Havent crossed that bridge yet....hardware I am OK with.....software and
protocols
are still a bit new to me.

>I am thinking of optically isolating the triac firing circuit from the
>control side (16C65) have you any thoughts on this you have obviously
>looked at commercial units, the one's I have seen have no isolation,
and I
>am worried one fault could Zap the lot ?

Most....if not all commercial lighting controllers that I have worked on
have some form
of opto coupler between the low voltage controls and the triacs. MOC3020 is
a popular
choice and its what I will be using. An alternative approach is to have all
the control
circuitry at mains potential and just a single opto isolator for the data
line. Needless to say
my preference is for optoisolators on each triac. I am also going to
include a relay on each
output to provide true isolation when the circuit is off. All triac dimmers
have a small amount
of leakage via the snubber circuit. This also gives the possibility of
controlling switched loads
and being able to dim flourescent lighting.

The wiring would be like this....
Live.....Fuse.....Relay......triac.....load......Neutral
There is an additional benefit in that if a triac blows (they almost always
go dead short so
that the lamp comes on full) it is still possible to turn the circuit off
until you get time to repair the
blown triac.

My reason for wanting a "switched live" as well as a dimmed live
is so that I can dim
flourescent tubes for concealled lighting. Dimmable ballasts require a live
feed to supply a
transformer which preheats the ends of the tubes. It is essential that this
is turned off when
you dont want any light as it consumes a fair bit of power and reduces the
life of the tubes.
It can also be turned off once the tubes are at full brightness.

>The big problem I have is time, I spend most of my spare time
renovating my
>house (1st baby due in Jan) and when I do get some time to write some
code
>it takes me three hours to figure out what my existing code does !
>Although I hope that will all change, my prototype is in assembler and
I
>am going to switch to C so that I can maintain the code, to make the
>transition easier I bought my self a ICEPIC.

My biggest problem (apart from lack of cash) is the 3 hours a day I spent
commuting.
Lots of time to think but no time to build :-((

My PIC programming experience is very little at the moment. About 2 years
ago I built
the Hank Schaer programmer and made a 16C84 do the flashing LED tricks but
I havent
really had much time since. I now have the problem that since upgrading my
PC I cant get
the programmer to respond so I am going to bite the bullet and get Picstart
Plus.

>My 4x4 keypad has up and down on each channel (8 buttons) and 4 scenes
(4
>buttons) leaving 4 spare for coms to other controllers on the network.

My keypad is now one year old, has 10 buttons matrixed, 10 tricolour LED's
and an
IR reciever and is waiting for me to get a PIC driving it !!! Pictures on
my website.

Keith
http://www.btinternet.com/~krazy.keith





____________________________________________________________________

List Site: http://www.findmail.com/list/ukha/
To unsubscribe, send to ukha-unsubscribe@xxxxxxx

FREE group e-mail lists at http://www.findmail.com