Step 7 : Electrical Boxes


You'll need an electrical box or two (I recommand metal) to hold
your outlets. If you look at the way the outlets are wired, you notice that the NEUTRAL (right side) of each outlet is connected together. For the NEUTRAL side, it is important that the tabs between the top and bottom outlet are not broken, but since we want each outlet to be controlled individually, the tab on the hot (left side) is broken.
I used 14-3 rubber coated wire because

• The wire is very flexible and much easier to work with than 14-3 solid wire.
• Each wire (Back, White, and Green) is covered.
• Bringing in 3 sets of coated wire provides 9 individual wires
  which is exactly what is needed to control 8 outlets (8 hot wires and one
  common ground).

Step 8 : Wiring Note


Note: The picture of the wiring can be really confusing because I'm using Green wires as HOT and the white wires can either be HOT or NEUTRAL. When doing odd things like this, the correct way to denote these changes is to Mark any HOT Green and White wires with back electrical tape. I didn't have any tape near by when I did the wiring, so I skipped that step. (full image)

Note: It would have been nice if 10 wires could have been easily brought in so that a common ground wire could have been used to ground the entire box. This can be accomplished by having the 110V pig tail that brings the AC current from your house, go directly into the boxes that hold the outlets rather than into the box that holds the relays. If wired this way, the ground and NEUTRAL wires from the pig tail can be connect to one of the outlets and then the hot (black) wire could be sent
up to the relay box though one of the nine wires that connect the outlets to the relay box. In that case, 8 of the 9 wires could carry the individual hot circuits down to the outlets, and the other wire would care the common hot circuit up to the relay box. Unfortunately, I build my demo box before thinking of this solution.

Step 9 : The Wired Relay Box


When wiring the relays into the box, the NEUTRAL terminals of the low voltage side can all be wired together (white wire). (I really should have used a much smaller wire since only 5vdc is being carried across, but I didn't have any handy. Surprisingly, the voltage drop by using 14 gauge wire is hardly noticeable.)

The incoming terminals of 110V AC sides can all be wired together too (black wire). This way 110V is available at each SSR, ready to be switch on.

If you want to include indicator lights in your boxes, make sure you get 120V indicators and connect them across the 120V AC side of your SSR. It is better to do it this way rather than using a low volage LED because (1) the indicator won't light if the SSR burns out, and (2) you aren't pulling amps from the computer's power supply to power to indicators. (full image)

Step 10 : The Control Wires


The last piece of the puzzle is adding the control wires for the parallel port. All I did is take a printer cable, and cut off the end that goes to the printer. Pins 2-9 on the parallel port cable should go to the individual SSRs (HOT side)and the ground wire (usually back with white stripe) should connect to the NEUTRAL side of the SSRs. (full image)

Step 11 : Controlling the Interface

Controlling the parallel port interface is really easy. Each of the 8 bits controls a circuit. Each bit has a number (bit 1=1, bit 2=2, bit 3=4, bit 4=8, bit 5=16, bit 6=32, bit 7=64, bit8=128). The only other piece of information you need is the I/O address for the parallel port. Normally, this is port 0x378 (888 in base 10). To turn on bits 3, 4, and 6 the basic code would be: out 888, 44 '4+8+32 = 44 Some sample code is listed to the right.

'Parallel port 1 is port 888 'Each bit is a circuit 'Examples 'out 888, 0 = all off 'out 888, 4 = #3 on 'out 888, 3 = #1,#2 on randomize timer Defint A-Z A=0 do     out 888, A 'Reset lights.     A = 256*RND     delay 1 'Wait 1 second loop 'Loop back