dimmable ballasts

[tgriffin]

So what exactly is the benefit of going with one? I'm assuming that since it says dimmable that it varies the output of wattage.

 

[mojo]

The advantage is that you can turn the light up or down over that section of the tank, if needed. You only have about a -30% / +10% range, but I wish I had that at times on my own tank...

 

[tgriffin]

K. So they can't be programmed to go from say 30%-100%-30%

 

[mojo]

Not that far, no. You could do 70%-100%-70% on a halide ballast with some ingenuity, but it would take some work...

There are some electronic ballasts (ok, only the IceCap 660 that I know of) that can be dimmed 0%-100%, but requires a separate $200 dimmer....

 

[darren24]

I use 2 Coralvue 250W dimmable ballasts. I used the dimmable feature to slowly acclimate my corals when I upgraded from 150W.

 

[acroholic]

If you were really clever, you could actually program some type of very slow motor to turn the manual dimmer knob on a CoralVue dimmable ballast. I have 4 dimmable CoralVues, and have though about it, but my electronics knowledge doesn't extend to tha type of DIY.

Radio Control Car type electric servos would be what I'd play with for that application, I think. They all have adjustable throw for braking, throttle adjustments, especially on gas powered vehicles.

You'd need to play with the throw adjustment as your control and have it come on at certain percentages during the day. The amount of throw in the servo at any time would correspond to where it turned the dimmer knob on the CoralVue ballast.

Hmmmmmmmmmmmmmmmmm!

 

[acroholic]

ares;438705 wrote: I would think youd be better off with some sort of controllable resistor replacing the dimming knob, perhaps harder to implement, but more efficient at doing it.

I'm not sure exactly what that means, but given my level of electronics knowledge, I'm sure you are right.

I was thinking of something that wouldn't require getting into the ballast itself. Would a controllable resistor mean taking apart the ballast?

 

[mojo]

ares;438705 wrote: I would think youd be better off with some sort of controllable resistor replacing the dimming knob, perhaps harder to implement, but more efficient at doing it.

That was my thought as well. You could use a digital potentiometer and a small chip to change a 0-10v feed into a given resistance. But, as acroholic said, this would require opening up the ballast and doing a little soldering. Not horrible, but does make it hard to revert, if needed.

 

[lilrobb]

There are ballasts out there that have just two wires for that resistor already hanging out...
Eric_B could chime in, he got these from me...