On Tue, 15 Jun 2004 21:47:06 -0700, Matt Davis
bubbled forth the following:

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.)

Hi Matt, welcome

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?
Check he
http://www.advancetransformer.com/te...g_Diagrams.pdf

0-10V DC, 0.5 mA (unknown if this is sink or source), the 0 V would be
the lower limit of the dimming range (1%-5% depending on tube type),
not off.

and he
http://www.universalballast.com/lite...g_brochure.pdf

This doc has basic diagrams towards the bottom. Mainly use this to get
the part number of the ballast you are interested in, then get the
data sheet from he
http://www.universalballast.com/prod...t/fl_dimm.html

The only current spec on the control leads I could find is they will
source 200 micro A, but nothing on what they would/could/need to sink,
if anything.

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...

I'd thought about a micro controller, but haven't looked into the cost
of one, especially the cost of the hardware to program one.

I'm also considering using one of my old 486 PC's to do the job. As
they can be picked up for $5-$10, this might be a low cost option.
It's also work as the power supply for the DAC circuit.

I have one that has 3 printer ports, so I could set it up as a print
server as well as to control two sets of aquarium lights, each with
their own program; wouldn't even need a keyboard, mouse, or monitor,
just a network card and then access it via VNC or PC anywhere.

Load it with DOS and write a QBasic program, or load Win95/98 and use
Visual Basic. Just have to spend a day or two to learn enough Visual
Basic to write the program to control the printer ports. Use 1 bit for
on/off, leaving 7 bits to control 128 different light levels. Could
even use the 2nd printer port to control water valves, and simulate
mid-day T-storms, even annual variations.

One other advantage to the dimming ballast is getting longer tube
life. Rather than changing the bulbs every 6 months as is sometimes
recommended, simply add in one more tube than you need, say 5 instead
of 4, and set your max intensity at 80%. As the tubes age, you
gradually increase the intensity to make up for the drop in intensity
as they age. This way you can use them for their full life span of 1-3
years; though with the newer T8 and T5 tubes (at least for CW, WW,
full Daylight tubes. Not sure if this applies to the specialty bulbs
for plants though), it seems they hold their intensity throughout
their life span, after an initial drop in the 1st 100 hours, so this
may not be very useful.

HTH

Jerry