Step 6 : Preparing the wires and the outlets


I cut off about 24 inches of wire off the computer end of the cord I use. This wire is used to connect the outlets together, and to connect the outlets to the terminal block on the SSR PCB. There are three wires in the cord. I cut the black wire into four equal pieces, then I tin one end of each wire. By tin, I mean I cut a little of the insulation off the end of the wire, I twist it together, dip it in flux, then put some solder on it. This keeps all the individual strands together and makes them easier to use in the terminal blocks (see the before and after in the picture above).

The next step is to prepare the outlets. The outlets have a small tab of metal on both sides. This tab connects the top and bottom outlets together. This tab needs to be broken off on the "hot" side of the outlet. This should be the side with the smaller slot, or the right side as you look at the outlet from the front. I just grab the tab with a pair of needle nose pliers and bend it back and forth until it breaks off. This picture shows the outlets before and after the tab was removed.


You can see that the top outlet no longer has the tab, and the bottom outlet is "before modification." Make sure you only do this to the tab on the hot side of both outlets.

Step 7 : Wiring it all up

I remove the outer insulation off about 5 inches of my cord (the computer end of the plug that I had cut off earlier). I have three wires in my cord. Black is hot, white is neutral, and green is a ground wire.

I tin the end of the black wire as I did with the other pieces I showed earlier.

I then fish these wires through one of the precut wire holes in my outlet box opposite the end the SSR is on. The black wire goes in the center terminal of the 3-contact terminal block on the SSR PCB. Tighten the terminal down by screwing in the screw on the top of the terminal.

Then I put the other 4 short pieces of wire I prepared earlier in the other four terminals. Connect these wires to the "hot" terminal screws on the outlets. I try to connect them in some sort of order from the top of the board to the bottom of the board. If you connect all of your outlet boxes the same way, you will know which plug is first, second, etc, etc.

I use a short piece of white wire to connect the neutral side of both of the outlets together (the side we did not break the tab off on). Then connect the white wire from the cord to other neutral terminal on one of the outlets.

Take a short piece of green wire and twist it with the green wire from the cord. Then connect this to one of the ground terminals on one of the outlets. Connect the other end of the short piece of green wire to the ground terminal on the other plug. We are probably not going to use the ground on our outlets, but I feel if you are NOT going to connect them to a ground, you should disable them somehow (fill them with hot glue??). To me, it was just better to connect them to my cord.

Re-mount the SSR PCB if you removed it, and that should bring us to this point.


You can see the cord coming into the bottom left corner of the box. The white wire runs up to the neutral side of the outlet, the other white wire is connected to the other screw terminal and goes to the neutral side of the other outlet.

A fuse may not be a bad idea either. With my planned usage, a 6 amp fuse on the hot wire should be about right.

Step 8 : Finishing assembly


Now it is as simple as mounting the two outlets, putting on a cover plate, and you are finished.

The picture in this step is the first one that I made. Note that the RJ45 jack is on the side of the box that is made to be nailed to the stud when used in a house. I removed the nails, and have not finalized how I will mount my boxes, but in the next box I made I had my RJ45 exit the other side just to leave the option of using these tabs open.

Step 9 : Heatsink (added 01 April 2006)

Ok, some may wonder why I added this step, so let me give a little background. In 2005 I made an 8 channels SSR that I used for my display. When I went to replace burnt out bulbs, I set my software up to turn all channels on, then went out to work on it. I had 1-3 strings of lights per channel, mainly 2 strings. I felt the tabs (was not using any heatsink) on the SSR unit and felt no heat at all. Well...someone questioned my sanity on this...so I did a little test. With the heatsink shown in this step, the tab/heatsink got a little warm after 10 minutes with one channel (out of four) of my SSR having 3 strings of lights on it (about 1 amp) for 10 minutes. I tried this same test again with no heat sink, and after 2.5 minutes, the tab on the TRIAC was uncomfortable to touch. So...I started putting heat sinks on my SSR units.

I found some aluminum angle iron at Lowes. It is shaped like an L with one side being 1/2 inch, and the other being 3/4 inch. I bought the one that was 1/16th of an inch thick.



Lowes also carried some that was 1/8th of an inch thick. I am not any sort of an engineer or anything, but my understanding is that heat dissipation is all about surface area, not about the thickness of the metal. So, I chose the 1/16th because it would be easier to cut.

I cut the angle iron into 2.5 inch lengths. I have a little table top sander I used to take the burrs and sharpness off the cut ends. Then I held the heat sink up against the TRIACs on the SSR and marked it through the mounting holes in the tabs of the TRIACs.



Then I drilled a pilot hole at each of my marks with a 1/16 inch drill bit. I do this by laying the angled aluminum over a piece of wood to stablize it, then drilling it with a cordless drill.



The screws I use are a self drilling type sheetmetal screw. The size is "6-20 x 1/2."



I install a screw in each of the holes using the same wood block I used when drilling the holes.



I use the same screw to make all four holes...then remove it. Now, take the heat sink and make sure there are no metal shavings on it at all (metal shavings and 115VAC dont mix). Wipe it, wash it, etc, etc...whatever you need to do to make sure there are no metal shavings left on it.

Now, apply a small dab of heat sink compound on either side of the holes in heat sink so it will be between the TRIAC mounting tab and the angle iron. The compound can be purchased at Radio Shack, or any computer parts/repair store. Heat sink compound can conduct electricity, so when using it, be careful where you get it, and don't use too much.

Mount the heat sink to the TRIAC mounting tabs with the screws. Here is a picture with two of the four screws installed.



Here is a picture of different views of the completed SSRs.



This is just an example of how to install a heat sink. There are many other ways that would also work. I chose to mount my heatsink on the face of the tab to allow room behind the TRIACs for an upright fuse holder I would like to use on the SSR PCB. I also noticed some U shaped aluminum stock at Lowes. If it had the same dimension, it would not take up any more space and should dissipate more heat (more surface area).

The example I gave here was implimented with "using 1 amp per channel" in mind. This, by no means, is designed to use max current per TRIAC.

Step 10 : Closing comments

Building the SSRs is definately the expensive part of this project, when compared to the controller. A 64 channel controller can be made for about $50. The 64 channels of SSRs and outlets will cost much more...

Cost: The cost of components is about $2 per channel plus the price of the terminal blocks and the RJ45 jack. (about 8-9 dollars total for the 4-channel before shipping)

The price of the PCBs can vary widely, depending on if you are have them made, or etch them yourself. Even the price of the blank PCBs varys widely.

The cost of the outlet box and plugs: I buy my outlets in contractor packs of 10 at lowes. They are 3.25 for 10 when purchased like this (so 33 cents each). I pay 91 cents each for the boxes and 72 cents each for cover plates.

Total:
$8 SSR components
$2 for the PCB
$2.29 box, plugs, and cover plate
$1.24 extension cord
$13.54 total before taxes, shipping, etc, etc

Now you need to make 16 of these for a 64 channel controller.

16 x 13.54 = $216.64, or you can translate that into "ouch."

Good luck with your Christmas light control projects!!!