RE: Re: LED Fun Challenge

[ian.bird@xxxxxxxxxxxxxxxxxxxxxxx]

My approach would be to use a 'nice' processor (simply because of the
output ability) from the Atmel range (my favourites). The inputs from the
user going to the stairs would have to be quick so they don't start up or
down the stairs before the lights have started to light up. I would time
this allowing for a running person I think. Options like this could be set
using a set of dip switches though. You may also want the lights to have
different delays which is where a micro would score. If in system
programming ability was fitted the guy could update it as he got to know
his requirements through experience.

I would use transistors as these can switch the LED's silently and quickly
and will support up to 4 LED's (or maybe more) depending on current flow.
Correct use of watchdogs etc. would make the unit very reliable and sleep
mode could reduce power consumption.

It is possible that he would decide he only wants the lights to come on
during the day so some sort of light sensor or fancy lookup table to
define 'on' times for every day of the year would be needed. Suddenly
feature creep becomes something to consider not to mention budget and
time.

Most of these things require a PCB which is added cost and time.
Everything is possible, it just costs money at the end of the day if
someone else does it or time and potentially less money if you do it
yourself. The above proposal could apply equally to Rabbit, PIC or other
well endowed processors depending on your favourite.

If you take the traditional cheap and cheerful approach I think you will
be disappointed with the results. I especially think that clunking relays
is unacceptable for this application!!

Ian







Mark Hallows <markhallows@xxxxxxx>
04/08/2004 10:37
Please respond to ukha_d


To:     "'ukha_d@xxxxxxx'" <ukha_d@xxxxxxx>
cc:
Subject:        RE: [ukha_d] Re: LED Fun Challenge


And if you build your own units with individual resistors on each LED
it'll
light up in cascade delay so it would look like runway lights.. Very
cool..

-----Original Message-----
From: Ward, David [mailto:DAvid.Ward@xxxxxxx]
Sent: 04 August 2004 08:46
To: 'ukha_d@xxxxxxx'
Subject: RE: [ukha_d] Re: LED Fun Challenge


If you want to go the controller route I recommend the Mitsubishi Alpha
units
limited I/O, but
You could you 1 or two transistor output versions that way you wouldn't
have
the horrid relay clicking sound and reliability would greatly improve

e.g.  The AL-20MT-D Has 12 inputs, and 8 transistor outputs, requires 24V
DC
Supply

The Alpha In A Box starter kit is good value and comes with programming
cable software and EEProm module

You don't need the EEPROM really, as the Alpha has non volatile program
memory, the software is very easy to learn drag and drop point to point
wiring with modules e.g. AND, OR, COUNT, FLASH, TIMER etc


No connection, just saved my bacon loads of times when projects came in
with
0 lead time - required this afternoon working and reliable =:O

For  a quick look see Farnell <www.farnell.com> order code  3354702


Dave

-----Original Message-----
From: David Buckley [mailto:db@xxxxxxx]
Sent: 03 August 2004 21:29
To: ukha_d@xxxxxxx
Subject: [ukha_d] Re: LED Fun Challenge


--- In ukha_d@xxxxxxx, "Rob Mouser" <groups@m...> wrote:
> A friend of mine has just moved into a new (very posh) pad.
> He has an oak and steel spiral staircase and wants to add
> some discreet LED lighting to it. But of course just on/off
> wont do! He wants to have pir activation from the top and
> the bottom AND when it is activated he wants the LED lights to
> come on in sequence one step at a time (Fairly fast.) and then
> all remain lit for a set period of minutes. But it doesn't
> stop there! .......

Clearly, money is no object here.

PLCs.  "Low cost" PLCs like the Siemens Logic, or one of the many
identical units, like the Crouzet, Moeller etc.  You'll need relay
output models with either an expansion capability, or use
several "basic" PLCs and chain one from another.

It'll take an hour to program, and work forever, with 100%
reliability.

Granted its on the face of it a much more expensive solution than
using a PIC and building something, but given that RS deliver stuff
next day it can be installed and up and running in a day.






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