On Thu, 10 Jun 2004 09:55:40 -0400, "Harry Muscle"
bubbled forth the following:

"The Outcaste" wrote in message
.. .
On Wed, 9 Jun 2004 09:21:41 -0400, "Harry Muscle"
bubbled forth the following:

"Hound" wrote in message
. com...
Quoted from a website: (refering to a Power Compact Flo set-up)

Our DIY systems include one ballast for every two lamps, thus creating
a great way to implement dawn & dusk simulation.

My question is if that is correct? I am currently looking to
build/purchase a 36" PCF that utilizes 2-55w bulbs. I plan on having
live plants and want to simulate dawn and dusk by having one come on
just before the other and vice versa and the end off the day. Can I
control each bulb or do I need more than one ballast to do this?
Aquarist resurrected

From a technical point of view, it is possible to control each bulb
separately, if you have the correct ballast, however, it is way way
cheaper
to just get two ballasts to do the job.

Harry

I haven't checked prices, but perhaps 1 dimming ballast would be
cheaper than 2 regular ballasts. I've seen 2 types, ones that work off
of standard 120 V dimming controls, and ones that use a 0-10V control
signal. Of course automating this would add some more expense.

Does anyone have any experience with this, and/or sources for
controllers?

Jerry

I've looked into this quite a bit about a year ago, and came to the
conclusion that it's easier and cheaper to just go with two normal ballasts.
The biggest problem with the dimming ballast wasn't the cost of the
ballasts, but the cost of automating it, since there isn't really a simply
solution for it.

The route that I took is two ballasts, connected to one bulb each, plus a 3
foot rope light. So in the morning, the light rope comes on first, which is
a nice low light wake up for the fish, then a couple minutes later the first
bulb, and then later the second.

Harry

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