[Marcus Watts]

Hi everyone,
I'm looking at the possibilities of creating a MH control box that does this:

400w ballast input - 2*400w output channels. Switched timing device so the time can be set for channel 1 (bulb one 6.5k) to run for desired period then turns off. A few minutes later timer powers up channel 2 and the 2nd bulb (20k) powers up for the next lighting period.

What i really need is this set up doubled up so 2 400w digital elec ballasts feed in and there are 4 output leads to the pair of 6.5k's i have already and the pair of 20k's that are going alongside in the reflectors. The ballasts will obviously only run one bulb at once and i'll have a small time delay between channel 1 off and channel 2 on to allow some cooling etc.

does anyone on our forum have experience with small programable cpu's? or have any other ideas or pointers?

Cheers Marcus

[chriss]

I've programmer pics and arduinos which would do the switching job easily, but adding buttons and a display for adjustments makes for a more complicated circuit. I use digital timers that fit in consumer units, each one has a two time switches, that would most likely be the easiest option. They can be picked up on eBay quite cheaply. You can also get solid state relays that will fit in a cu for use as contactors.

The other option is a dedicated fish tank computer like the one jas has.

Chris

[Marcus Watts]

chriss, on Jun 27 2010, 08:19 AM, said:

I've programmer pics and arduinos which would do the switching job easily, but adding buttons and a display for adjustments makes for a more complicated circuit. I use digital timers that fit in consumer units, each one has a two time switches, that would most likely be the easiest option. They can be picked up on eBay quite cheaply. You can also get solid state relays that will fit in a cu for use as contactors.

The other option is a dedicated fish tank computer like the one jas has.

Chris

Thanks for this Chris, its looking quite promising. If it simplifies the timing & adjustment I want 5hrs channel one (6.5k) and 5hrs channel two (20k)
I'm happy not to fiddle about with aditional adjustment, just a fixed 10hr metal halide day 365 days a year, split between the two bulb temperatures.
I think i'll need a little help and advice with construction unless you would be happy to come up with a price to make the unit for me (not looking for pretty, looking for just effective) - i'll be the guiny pig for the most useful MH device since the ballast!!hahaha. I can get the cables, E40 bulb holders etc easily enough,

And if anyone knows which 20k bulbs are good and perform with digital electric ballasts rather than mercury it would be a great help to, as some companies' bulbs require the older style ballasts i believe.

cheers again, marcus

[Marcus Watts]

Hi Chris,
Currently I use this combined timer / relay to control the two 400w ballasts/6.5k bulbs. Will it have some of the components needed to construct the bulb switching device I'm trying to make? I have 3 spare digital consumer timers that could be stripped down too, are they along the lines of the bits you talked about?

cheers for any advice Marcus

http://www.progrow.c.../info_4825.html

[chriss]

Hang on a minute, are you wanting to use only TWO ballasts, switching their OUTPUT between different lamps rather than FOUR ballasts?

Thats a different matter, tho should be totally doable providing we can find a suitably rated relay and make sure the ballasts turn OFF before switching outputs.

I would use a time switch like this...



... you can usually find them on ebay for around the £20 mark or less, tho I can't find one quickly right now.

The relay could be a little trickier since the contacts need to be pretty highly rated, but if the units are powered off before the switching is done then that might make it easier and I would suggest you get a double version of the above timer, one channel for turning the ballasts on/off and the other for switching the relays. Using a single double version of that switch will ensure we don't have any clock-synch issues.

You will still need a contactor of sorts between the timeswitch and the ballasts. I expect the one you have just has a heavy duty timeswtich rather than a relay, meaning it's not much use other than as a case and some sockets.

We need to find a timeswitch and a relay - might be good idea to run this by karnivor too.

Using one of these timeswitches over a pic/arduino saves a lot of hassle, is easier to implement and gives you more flexibility. The biggest ball ache with IC route is you need a separate chip for the clock, this needs to have it's time set and then power maintained to it. This incurs a lot of overhead since to set the time you need a display, buttons etc etc.


Chris

[chriss]

Oooh, here you go...



Merlin Gerin Din Rail Digital Timer

wouldn't even need a contactor with this one since it handles 10amp inductive load.

[chriss]

You could probably use some industrial contactor relays off ebay, I suggest we switch both live and neutral on each lamp, and use separate relays for each one too. We want to avoid any arcing issues.

 marcus_01.jpg (50.96K)
Number of downloads: 1

Chris

[Marcus Watts]

Thats it m8, exactly the layout i'm looking for - 1 plug, 2 ballasts, 4 bulbs - for safety we can build in 15-20 minutes 'off' time between the switchover and we're cooking on gas. I'll get the bulbs, bulb holders, cables sorted and do the rebuild on the reflectors to house the 4 bulbs, then we'll have a chat at frag night an i'll get the bits on the shopping list. Even if my current box has relays i'll leave it intact as it will sell quickly as a 1 plug/2 ballast/timer/control box.

cheers - this is going to be gr8 - 6.5 & 20k days over the tank - growth and colour - perfect world

[Marcus Watts]

oh, and i got an account at els so can probably get relays etc locally - its where i got the 18 switch gang box set up to do away with all my extension leads and plugs - all pumps, tunzes, heaters etc etc are hard wired into the box so i can turn stuff on and off at the flick of a switch