Using SSR's in my Christmas light display...

Thread Starter

Holiday Lights

Joined Feb 5, 2007
I am working a MEGA-TREE project for my 2007 Christmas light display. I am using Light-O-Rama ( light controllers. I am using the 16 Channel (CTB16D) controller. I want to split the channels to allow more strings of lights than what is normally able to be connected. Instead of just having 16 strings of LED lights connected to the LOR, I would like to control 128 strings of LED lights using solid state relays. I have a very basic knowledge of building circuits and any help would be greatly appreciated...

In AutoCAD, I have split the tree into four (4) quadrants with eight (8) string connection points in each. I want to connect each quadrants "CH. 1,2,3, ect..." circuits together as depicted above. When the LOR controller sends power to "CH. 1", I want it to power all four (4) quadrants "CH. 1" connection points to be switched by four (4) SSR's.

I plan to connect the neutrals to a series of SSR's also. Each quadrant will have it's own relay, and the bank of neutrals for each color of LED light strings will have its own relays per quadrant. Depending on which quadrants SSR is closed, those lights will be powered. Also depending on which colors SSR is closed, only that color will be powered in that quadrant.
EXAMPLE: I can light the red strings in the NW QUAD while lighting the green strings in the SE QUAD at the same time all the while controlling each individual string with the first eight (8) channels of the LOR controller. (I understand that each quadrant will have to do the same thing at the same time...)

I want to use the first eight (8) channels to direct the light animation for all quadrants, and use the last eight (8) channels to control the SSR's. Above, I have layed out the schematic of the enclosure in AutoCAD.

Above is the preliminary design of the SSR side of my enclosure. The eight (8) channels shown entering from the top right switch the SSR's. The first four (4) channels switch the individual quadrants and the last four (4) switches the color of LED light strings per quadrants. The SSR's are labeled according the their purpose.

A close-up of the LOR side of the enclosure for GP is located HERE.

  • Is this schematic feasible using AC current?
  • Can I connect multiple strings of lights to a common neutral and use the LOR to switch the individual light strings on and off?
  • Can I switch multiple SSR's with an AC current?

Thank you for looking...


Joined Apr 20, 2004
Unless you have some overriding reason for using SSR's, why not use plain old relays? A P&B PRD type will cost about 1/5th the amount of a similarly rated SSR, and has better ability to handle tungsten loads, in case you mix in some old bulbs.

About the only thing you might lose is a slow on/slow off, or running dimmed.


Joined Jun 30, 2006
I know it's possible I'm just not able to figure out what chip(s) will work as it seems to be a fairly complex circuit.

I think there are chips that can convert/decode the binary number which is represented by 16 positions (16 digit binary number) but I just don't see it.

If I have only two output 'bits', a two digit binary number, I should be able to get 00, 01, 10, 11 out. or four possible 'on/off' values that can be decoded.

Three bits 000 001 010 011 100 101 110 111 or eight possible 'on/off' values.

The more outputs/bits you start out with the higher the number of outputs 'on/off' values. Well that's what I think should happen but...

Oh, as has been said find the absolute maximum voltage and current and find the right relay. I suspect you could get vastly cheaper SSR relays but if you can drive an SSR you can drive a coil. SSRs are hideously expensive unless you get some potential junk off of ebay. (grumbles)
Check Digikey once you find those current values. There are other vendors but I like these folk.


Joined Jan 26, 2008
MRMEVAL: I think the following chips will do what you describe:
74LS138 - 3 to 8 - Decoder/Demultiplexer
74LS139 - 2 to 4 - Decoder/Demultiplexer
I suggest that you google for "74LS00 series" and you will get multiple hits on digital ICs with various capabilities. You will also find sources for datasheets and application notes describing how to use these chips. Regards.