High Voltage/Current switching (Christmas Lights)

Other Hardware Motors, Mechanics, Power and CNC
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I would like to control some christmas lights with my Arduino. At this stage I am wanting to control more channels than I have output pins. So I am using a Shift Register IC that I have from another project (MBI5026). I have that all working fine so there is no problem there.(64 channels with software PWM :)) I am trying to work out the connect from the IC to the lights. I have been looking on external DIY christmas sites and they are using DCSSR's that they custom make. ( I have a variety of lights but they will all be running DC)

So the question I have is about the way DCSSR's are setup. All the ones I have been looking at have opto-isolators that then drive a big mosfet. Is the isolation necessary? I have seen examples on here of people driving large loads with mosfets directly from arduino pins (in some cases). These lights will most probably be 24v-36v DC at maybe up to 5amps(more like 1-2amps). I will have a big centeral seperate power supply.

if opto-isolation is not needed then which mosfet should I use? Should I use Opto-isolation even if not "Necessary" but just in case?
I suppose as a DIYer I am trying to find the most cost effective way of doing this per channel as there are a number of channels to control.

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Thanks for that. Country on my profile updated.

Thanks for the general info. I wasn't sure exactly what to look for.

The IC is a current sink so does that mean I am looking for a P channel FET?
What would be the potential downside of tying the the GND's together be?

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Ok looks like I might have to go look more at FET designs. I am only familiar with simple transistor switching.

Currently the setup I am looking at would be something like this:
Laptop -> usb/serial -> Arduino -> MBI5026 -> FET -> Lights

Wow that looks complicated when you step it out. :slight_smile:

The patterns are generated on the computer and state information is sent to the arduino to act on. I see now if I tie the Arduino to the GND of the lights powersupply I am tying in the laptop as well (right?).

I am thinking for ease of building for a novice (me) I should probably just use the opto-couplers and build the DCSSR as per current designs. I was hoping to bring the cost per channel down but for confidence and reliability I think I will go with the tested design.

Thank you so much for looking into this.