On Fri, 11 Jun 2004 05:07:09 +0000, The Outcaste wrote:

snip discussion on sunrise/sunset using dimmers & multiple ballasts

Did some looking today and have to agree with you. The controllers I
found were for commercial use. Some of the home automation systems
would work, as they do have dimming modules, but you'd have to invest
in the controller, and I'm not sure how programmable they are.

It's be pretty simple (at least for an electronics hobbyist) to build
a controller to plug into the timer you are already using; a 12 VDC
supply, a 16 bit up/down counter, and a Digital-Analog Converter
(DAC). This would allow either a 4.5, 9.1, or 18.2 minute ramp up/down
time. The change in intensity would depend on the resolution of the
DAC. 2 bits would give 4 levels, 8 bit 256 levels. Hardest part would
be the sunset dimming. Have to add a relay and 555 timer to keep power
on for 10-20 minutes after the main timer turned off while the
counters count down.

Another option is to wire the DAC to the parallel port on a PC. I'm
not enough of a Windows programmer to write a program to control it,
but it would be very easy.

Hmm, I sense another project to add to my list...

Jerry

I just started doing research for this a bit myself today. I stumbled
across this thread by pure chance. (:::stands up::: Hi everybody. My name
is Matt and I'm an aquarium automation addict.)

I'm finding it hard to get reasonable specs and wiring diagrams from
manufacturers' web sites. They (probably sensibly) assume that you're
going to attach the thing to one of their enormously expensive, centrally
controlled, building-wide control systems. Most of them seem to
consist of, "Just plug our neat digital control computer in here, and
you're done!" What manufacturers were you looking at for this?

As for the timer, I was thinking about a PIC microcontroller rather
than a counter for a more flexible sunrise/sunset cycle. Something that
would start slow and speed up as the "sun" hits the "horizon." With a
proper clock set up, you could theoretically avoid the need for an outside
timer as well. For real flexibility, you could even add a serial port to
change the settings...