I have had a number of people ask me how I have made my 4 and 6 way powerboard SSR's, so I decided to add a section to the webpages on how they are made.

BE WARNED. This can be lethal!

The 4 way powerboards are pin-compatible with the standard Grinch/Renard output to a 4 way SSR board with some minor changes. Only 1 pin is used for the +5V supply to the SSR, and there is no Zero volt line to use to illuminate an LED on the board (Although this could be used if required on the 4 way board). The other 2 SSR's in a 6 way board use the Zero volt line and the unused pin next to it, and a custom cable will be needed to supply 2 6 way powerboards from 3 Grinch/Renard outputs.

Preparing the case

To prepare the case for SSR installations, firstly it is disassembled and all the power connections are removed. The plastic surrounding the earth pins is removed and ground down with a small grinding attachment on the Arlec supertool (a small Dremmel). Because all the 240V items I wish to control do not have earth pins, there is no need for the earth section of the powerboards to be there, so this allows placement of the SSR in the space previously occupied by the earth pin.

Earths removed

Here you can see the earths removed, but this leaves one problem - there's a hole in the board over which we want to mount the SSR's, so we need to fill it with something strong enough to handle average wear and tear. Hot Glue, used later, is good, but not strong enough for long term use.

Filled with Araldite

The holes are filled with Araldite which takes 12 to 24 hours to go off. I prefer the normal cure to the 5 minute one as it allows time for the bubbles to dissipate in the mix, plus it is a little stronger. A piece of electrical tape run across the front of the powerboard stops the araldite leaking through and sticking the powerboard to the bench, and is easily removed the following day. Because the outside of the hole flairs out a little (to help guide the pin in the hole), the Araldite forms a really solid plug in the hole, and is almost impossible to get off, short of grinding it off. Once the Araldite is set you can gently grind off any really high spots, as you want it 2 to 4mm thick at most.

The Active bar inside the powerboard is normally linked as one solid bar, but because we want to switch each active seperately, you first need to cut the actives apart.

Actives

Once the Actives are cut apart, I gently grind the edges and corners to ensure that there is no part of the metal that could rub and cut into any of the wires inside the case. A small hole is drilled in the centre for the next stage. I tend to rough up the sides to help the solder "stick" better, but I realy doubt that it is necessary.

Wire in place

A 10cm length of wire is soldered into the hole, and plenty of solder used on both sides of the hole to ensure that it should not come apart from the active connection at all. I think that wire is 1mm square, but in previous powerboards I have used wire between 0.8mm and 1.5mm without any issues.


The Electronics

Now to the Electronics. I designed the SSR's in this setup to be as small as possible, so they are made using stripboard cut into extremely small pieces, 3 holes wide by 9 holes long, and they have 3 gaps cut in the tracks - one under the Optocoupler, and 2 on the 240V side (although 1 does not have to be there now, due to changes in the design of the connection).

Boards

Here are the "completed" boards. It is possible to make them 1 hole shorter, and mount the resistor slightly differently, but this is the same design as I used last year and it worked, so why change. The boards look messy in this picture, but they have yet to be cleaned, so they are still very dusty. A solder-through coating is sprayed on the boards after they are cut, had the tracks cut, holes drilled for wire, and then gived a light clean with a small wire wheel to ensure no metal is left bridging the tracks.

Opto's

Here the MOC3023's are added. No socket is used as these are designed to be SMALL and not real easy to work on. Notice the enlarged holes for the wire (Centre row at the end) and the triac (2 holes in the second row... Why not 3 holes???? Wait and see!)

Add resistors

Here are the resistors added. The colors look horrid, but they are in fact 330 Ohm resistors - the joys of taking a photo under Flourescent light without a flash. You can see where I mean that the board could be shortened by 1 hole if the resistor was mounted across the board, not offset like it is there. It would just mean not soldering the centre pin of the opto, changing the location of the cut track, or simply cut the centre pin off. It sounded like too much work at the time, so I opted to go this way instead.

Almost complete

Here are the almost complete boards. They only lack the input resistor and the connection to the 240V and load. The Opto's have a small clearance between them and the Triac's, but because the load is limited to 1A max per Triac, heat is not really an issue. Most of the loads these drive are actually closer to 0.5 to 0.8A, so the triac's dont even get warm. I tend to use higher rated Triacs in the powerboards as the higher rating tend to dissipate less heat at the low loading of these units. At 1A load, a 6A triac gets warm, but a 12A triac (which were used this year) barely change from ambient temperature.

Adding the output

Here the output connections are added, followed by 2 layers of heatshrink tubing. The heatshrink is to give a nice finish as well as lessening the chance of any shorts. I made a unit last year and dropped it about 20 times onto the concrete from 5 foot high. The only thing that happened was one of the solder joins on this wire came off (as it is bent about 110 degrees when installed), so the heatshrink provides a little mechanical support as well.


Fitting it together

Once all the parts are built, the last stage is to wire it up and install it into the case. A length of wire is soltered to the board to be connected to the Active, and a piece of 6 way ribbon cable is soldered to each of the inputs to the Opto's. The common +5V is looped between each of the resistor inputs on the opto's and the resistors are covered in heatshrink to help keep them insulated.

Installing into case

Here you can see the beginning of the installation process. After the wires are connected, a big dollup of hot glue is put on top of the araldite put in earlier, and the SSR is placed in place and held to stop it moving until the glue hardens. Last year I tested the hot glue for resistance to high voltage and it was excellent, but this year I decided to check to see if the glue would absorb moisture, and it appears as though it does not cause a problem at all - after 24hrs immersed in salt water, 2 electrodes surrounded by about 3mm of hot glue, and about 4mm apart dropped from 80Megohms to about 75megohms when using a 500V Megger.

Almost there

Now we have the SSR's in place, the Neutral link installed, and the control and active wires in place. A few strategic dobs of hot glue can be used to hold the wires in place across the top of the powerboard - I usually put a strip of glue about 5mm wide in the middle, and then once all the SSR's have been tested as working then I put a few additional strips of glue in place to ensure that the wires will not move at all. You can see the bend in the wire that runs from the SSR to the active connection, so it's reasonably important that the wire is the right length - too long or short and it will place undue stress on the triac end of the connection.

Completed

Here is a completed 6 way board, tested and ready to have the wire clamp installed and then the back placed back on. It's usually at this time I add more hot glue to stop things moving too much.

Other 2008 pages

2008 Main page
Building the display
Minitrees
Powerboard SSR's
Shed Upgrades
Vixen & Ledtriks Files



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