RSM Max 250 moon lights

PostPosted: Tue Oct 04, 2011 6:17 pm
Hi

I am planning to get a RA to control my Red Sea Max 250. The lighting system has 6 T5 lamps which I have split into 3 groups of 2. I use timers to produce the lighting changes througout the day, so I can see how they can be covered by using relays.

There are 8 moon light LED's in the hood, working on one 12v DC circuit. I would like to be able to control them following the moon cycle.

Can I just connect them straight to one of the PWM chanels, or would I need to split them into two circuits?

Or would I need some sort of driver circuit?

Any suggestions will be welcome.

I have a programing background and the Open programming system of the RA looks good on review.
Last edited by Sebyte on Wed Nov 02, 2011 4:40 am, edited 1 time in total.

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PostPosted: Tue Oct 04, 2011 6:39 pm
Hi Steve,

You can do your lighting system with no problem.
Now, the moonlights will need some further investigation.
The PWM channel is limited to about 40mA per channel.
I don't think you can use one channel for all 8 LEDs, but you may be able to get by splitting them into 2 strings. You will need to measure the current before connecting them to the PWM channel to make sure it won't exceed the 40mA.
The RA dimmable moonlights draws about 35mA with 3 LEDs.
Roberto.
PostPosted: Wed Oct 05, 2011 8:29 am
Thanks Roberto

I looked up PWM on the Arduino site and have a clearer understanding of how it works. I will check out the mA before making connections.

Thanks again

Steve
PostPosted: Tue Oct 11, 2011 5:24 pm
The moon lights will draw around 80mA, so they would need to be split over two PWM channels. I would like to use only one, channel as I have a use for the other. From my limited electronic knowledge I think I would need to build an OpAmp which would control the Voltage (with the higher mA) on the secondary side.

If there is anyone who could suggest a circuit that would work I would be greatfull

Thanks

Steve

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