The heatsink I don't feel is adequate to support really large currents. Though I can get 15 and 25 amp alternistors, I don't think the heatsink can dissipitate that much heat. I feel pretty comfortable powering 300-500 watts but not much more.
First I made a little PC board. The board will have the 2 resistors, the optoisolator and the capacitor. The components can also be mounted on a piece of "perf" board and wired up. Radio Shack has the bakelite boards with 0.1 inch spaced holes. The board needs to be less than 1.5 inches long and 0.5 inches wide to be mounted on edge like I mounted my SSR PC board.
-I removed the back of the case from the module by lifting up the four corners.
-I had to remove the screw on the triac to remove the PC board from the module.
-I had to slip a knife between the case and PC board on the side opposite the dials to get the PC board out of the case.
Parts from the Wall Switch module board are removed. Essentially, the triac and
everything connected to its gate pin all the way back to the transistor.
-The connections to the large, black, cylindrical inductor is unsoldered and the inductor is removed from main circuit board.
-I removed the triac; resistors R3 (1K), R8 (39 ohm); diodes D11, D7. The parts are not labeled too clearly so component numbers are my best guess. These are the components connected to the gate pin of the triac. The photo shows the components I removed. In addition, I removed the black wire and the 330K resistor (called it R330K since I could not see the printing); both of which will be relocated later.
Here is a picture of the parts I removed:
At this point, a couple of parts need to be relocated and some modifications to the board are required.
-A short piece of ~22 AWG wire is soldered to the 330K resistor which was removed. One end of the resistor will be in one of the holes the inductor was in and the other will be in one of the holes the 330K resistor was in. What I want to do here is two fold. I wanted to evacuate the components connected to the triangular shaped pad under MT2 pin of the Triac so I can bring Line voltage to this pad. The other reason is that with this mod, I can use the original blue wire to connect to Neutral so the X-10 chip can detect zero-crossing. That is why I moved the 330K resistor.
-To make the original blue wire the neutral, I did not want the little cut-off switch under the button to move around. I took the little piece of metal in the slide switch and soldered it permanently in place on the back side of the PC board. I threw the spring and copper knob in the switch away.
-Two holes on the board needs to be enlarged to handle 18 AWG wire. One hole is where the R330K resistor was on the triangular pad connected to MT2 pin of the triac. The other hole is the D7 diode hole connected to the Gate pin of the triac. Care must be take when drilling out the holes. The first time I tried this, the edge of the larger drill bit started to rip the copper from the board. In subsequent mods, I put the drill in reverse and drilled at very high speeds. This wore the copper away slowly until I had a small divot. Then I put the drill in the forward direction and continued to drill through the board.
-Since Line voltage is going to the wrong pin on the alternistor, a little modification to the alternistor is necessary. I bent the MT1 pin up at a right angle and soldered an 18 AWG wire to it. This is going to be the Load wire running out of the module. I also put a shrink wrap tubing over the pin to avoid shorting things out. The right angle pin will rest on top of the PC board. At a later point, maybe a big dab of silicon or hot glue can be applied to secure the wire in place.
-A jumper needs to be installed between the MT1 hole of the triac and the hole directly behind the MT2 pin (the inductor used to be in this hole). I cut a small piece of wire from the inductor and scraped the outside of the wire with a knife just in case the wire had lacquer on the outside. This wire will be installed on the solder side (bottom) of the PC board. I bent the ends of the wire at right angles with needle-nose pliers and trimmed the ends to little stubs. I did not want the ends to poke up to the component side of the board. What I am trying to do is to bring line voltage to the MT2 pin of the alternistor. Since the MT1 pin of the alternistor is bent up (mod above), it will not go back into the original MT1 hole, where line voltage will also be.
Here is a picture of the bottom of the PC board and the modified alternistor:
-I did not want to solder anything connected to the alternistor pads yet, since they are pretty large, I did not want solder flowing all over the holes. OK, now I am ready to start soldering the alternistor and parts connected to the alternistor.
-First comes the MT2 pin. I positioned the alternistor into the old triac holes. Since MT1 is bent up, I stick MT2 and Gate pins into their respective holes. The little jumper wire between MT2 and MT1 is put into place and the black wire is put into the drilled out (R5) hole. I soldered all these parts at once.
-Next comes the MT1 hole. The other end of the jumper should be in the MT1 hole (from underneath the board). The Line signal wire from the SSR PC board goes into the hole where the old black wire was. I soldered all these components to the board all at once.
-Finally, comes the Gate pin. The Gate signal wire from the SSR PC board goes into the enlarged D7 hole. I soldered all these components all at once.
-I will need to get to the logical ground and -15V on the Wall Switch module circuit board. Since I removed some components from the board, I can reuse some of the holes.
-The wire from V+ is connected to logical ground. I picked a hole along the edge where R3 used to be. This hole is next to a large hole; not the hole that is connect to the gate pin or the triac.
-The wire from V- is connected the switched -15V at the collector of the transistor. I soldered the wire into the old R8 hole along the edge of the board next to the transistor.
This shows placement of components to finish the mod:
Here is how I wire up the module to the power system. The black wire goes to Line or Hot. The original blue wire connects to Neutral. The wire from the MT1 pin of the alternistor is now connect to the Load.
Here is what the finished mod looks like. Notice the R330K resistor with the little
white wire and red shrink wrap tubing attached to it. Also notice the MT1 pin on the
alternistor bent up (it is wrapped with a white shrink wrap tubing).
Before the PC board can be put back into the case, the bossing and cross piece around the slide switch on the front part of the case must be remove. Also, some bossing on the back part of the case where the inductor was located needs to be removed as well.
The board should go back into the case. Screw the alternistor to the heatsink. Run the wires through the wire relief in the back of the case. Close everything up. I can now control fluorescent lights or light-duty appliances with this modified wall switch.