DC48 Controller (DMX - DC)

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A very nice layout David, the board is really looking great. I think you will have got a lot of peoples interests with that picture. Looking forward to seeing it in action
 
Nice an neat board, how much is it again?
having a built prototype to look at makes it easer to justify the price.
How long till you have the bugs sorted in the firmware?
is the board prebuilt? is there much heat off the mosfets?
 
I did some work on the DC48 firmware this weekend. It now accepts DMX input and controls the outputs.

The DMX start channel is fixed at 1, until I write the code for letting the user set it via DMX.

The DMX LED indicates:
Flashes briefly with each DMX packet received
When DMX is lost (1.5 secs), flashes once per second
After 10 seconds, lights fade to zero and LED stays off
 
Are we there yet? (I love using that line :) )
Nearly a week since the last update.
 
Sorry, a couple of new AVD projects and some family stuff got in the way this last week. I hope to test the current capability this coming week.
 
I've been doing some power testing on the DC48 this morning. Logically, it's all running well. What I'm trying to do is optimise the performance; output current vs heat vs cost. Because the MOSFETs are not heatsinked, there is a limit to how much current each one can sink without excessive heat dissipation. I could change to better MOSFETs, but the increase in cost is substantial.

Bear in mind that there are 24 outputs per side and each side is limited to 20 amps anyway. If you average that out, each output is less than 1 Amp. In reality, some outputs will be loaded more than others and you may not want all outputs on full at the same time.

Due to the nature of Christmas lights, specifying the output current capability is quite tricky. I've tested it with some 3 Amp loads and the MOSFETs do get quite hot, especially if run for extended periods in the 70% to 95% level range. Mind you, at 3 Amps per output, that's only 7 (out of 24) outputs used before you're over the 20 Amp (per side) limit. As you can see, with a large number of outputs, it becomes a tricky balance of channel vs total current.

With the current type of MOSFETs, I could say 1 to 1.5 Amps per output with a max of 20A per side (24 outputs) and that would be completely safe. Would that suit the people that have expressed an interest in purchasing?
 
David_AVD said:
I've been doing some power testing on the DC48 this morning. Logically, it's all running well. What I'm trying to do is optimise the performance; output current vs heat vs cost. Because the MOSFETs are not heatsinked, there is a limit to how much current each one can sink without excessive heat dissipation. I could change to better MOSFETs, but the increase in cost is substantial.

Bear in mind that there are 24 outputs per side and each side is limited to 20 amps anyway. If you average that out, each output is less than 1 Amp. In reality, some outputs will be loaded more than others and you may not want all outputs on full at the same time.

Due to the nature of Christmas lights, specifying the output current capability is quite tricky. I've tested it with some 3 Amp loads and the MOSFETs do get quite hot, especially if run for extended periods in the 70% to 95% level range. Mind you, at 3 Amps per output, that's only 7 (out of 24) outputs used before you're over the 20 Amp (per side) limit. As you can see, with a large number of outputs, it becomes a tricky balance of channel vs total current.

With the current type of MOSFETs, I could say 1 to 1.5 Amps per output with a max of 20A per side (24 outputs) and that would be completely safe. Would that suit the people that have expressed an interest in purchasing?
Click to expand...

When we look at things like RGB strip which draw 0.2 amps per channel per metre (30LED/M) then the standard 5 metre length will be easily accommodated by this controller.
So i dont see a major issue with the specs of the board as its LEDs and not Incandecents that most would be using this low voltage DC board with.
 
The way I see it is that people using a large channel count controller will be splitting their lighting loads up anyway. That's the whole point of the DC48 really.

I just wanted to make sure people understand this before loading them up with 48 x 5 Amp loads!
 
The Tiger48 had the same limitations anyway. As long as its documented it shouldnt be an issue. Otherwise offer a larger current draw variation at a higher cost
 
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