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Assembly and Operating Instructions for Kits


Instructions for Building the Opto Switch 2 (COS2)


Assembly instructions for other kits


Photo Gate 28




For individual photos of the parts supplied in the kit, see the Parts List.


If you would like to refer to a circuit schematic while you work, download one here.


In these instructions, click on any image for a larger view. (In order to open the image in a new tab or window, right click and select open in new tab or window.)



Tools that you'll need


Having the right tools will make the job easier. You'll need to provide your own. Here's what we recommend.

  1. 15-30 W soldering iron and solder
  2. Wire stripper (photo below)

  3. A small diagonal cutter (photo below) makes it easy to trim stray wires, but other kinds of snipping tools such as scissors may work.

  4. Needle-nose pliers (photo below) make it easier to handle wires, especially if you have big fingers.

  5. A magnifying glass is useful to inspect solder joints.

  6. A lighter or matches to shrink heat-shrink tubing, if the project requires it. (not needed for this project)

  7. A drill motor and 1/4-in and 3/32-in bit sizes

  8. Emory paper or fine sandpaper
  9. Rubber or contact cement to affix the label to the project box lid

  10. Hammer and a pointed instrument such as a large needle or a punch
  11. Stencil or razor knife and a straightedge
  12. Hole punch such as that used for punching paper for binders
  13. Mild solvent such as denatured or rubbing alcohol and soft, clean cloth
Wire strippers diagonal cutter needle-nose pliers
Wire stripper Diagonal cutter Needle-nose pliers


Be sure to solder in a well-ventilated area. Keep the tip of your soldering iron clean by wiping it against a wet sponge. Once the tip is clean, touch a bit of solder to the tip to tin it and improve heat conductivity. Inspect your solder joints to see if the solder flowed well to make good electrical contact. If it looks like the solder formed a bead, that's likely a bad joint and will not conduct. Reheat to flow the solder.


The PCB and hole guide

Step 1. The hole guide


Photos 1a,b: These photos show the front (Photo 1a) and back (Photo 1b) of the PCB. We recommend lightly sanding the copper on the back of the PCB with emory paper or fine sandpaper in order to remove any oxidation.


Photo 1c: This photo of the front of the PCB includes an overlay indicating networks of holes with red (lettered) and blue (numbered) lines. This overlay will be used to aid in placing wires and resistors in succeeding steps.


Photo 1a Photo 1b Photo 1c


Step 2. Adding the IC socket to the PCB


Photo 2a: Place the 16-pin socket on the PCB as shown in the photo. Some of the letters and numbers have been overlain to aid in correct placement. The pins are seated in rows B and C and columns 1-8. Note that the notch in the socket is toward the left.


Photos 2b,c: Photo 2b shows the back of the PCB with the 16 pins sticking through. Crimp the pins over to hold the socket in place as you solder. Be careful not to create solder bridges between pins. If you do create a bridge, run the tip of the soldering iron between the bridged pins to clear the excess solder. The final result is shown in Photo 2c.

Photo 2a Photo 2b Photo 2c


Step 3. Adding wires to the PCB


Photos 3a,b: For this part, use the piece of black hook up wire. Strip the insulation back about 1.5 in. Then snip off three 3/16-in sections and two 3/32-in sections. Bend these into U shapes as shown in Photos 3a and 3b.


Photo 3c: Insert the U-shaped wires in the locations shown in Photo 3c. The connections are listed below.

  • 3/16-in wires: D1 to D3, D5 to D7, E3 to E5
  • 3/32-in wires: A2 to A3, A6 to A7

Photo 3d: Solder the wires on the under side of the board and clip off the excess. The soldered under side is shown in Photo 3d.

Photo 3a Photo 3b Photo 3c Photo 3d


Step 4. Adding the resistors to the PCB


Photo 4a: Insert the four 680 ohm resistors into the locations shown in Photo 4a. The lettering-numbering scheme is overlaid on the photo of the board for convenience. The connections for the four resistors are the following: E2 to E10, F4 to G12, E6 to C9, E8 to G11.


Photos 4b,c: The under side of the board is shown before soldering in Photo 4b. Do the soldering now and clip the excess leads. The completed soldering is shown in Photo 4c.


Photo 4d: Cut another 3/16-in section from the stripped black wire. Insert and solder between holes H11 and H12 shown in Photo 4d.

Photo 4a Photo 4b Photo 4c Photo 4d


Step 5. Adding jumper leads to the PCB


Photo 5a: Strip each of the red and white wires back by 1/8 in and solder into the locations shown in Photo 5a. (red wire to K15 and white wire to C10)


Photo 5b: Cut each of the blue, green, and yellow wires into two equal sections. Strip one end of each of the 6 sections back by 1/8 in. Solder the wires into the holes shown in Photo 5b. These holes are listed below.

  • Yellow into J14
  • Blue into J13
  • Green into I4
  • Yellow into I5
  • Blue into I6
  • Green I8

You can now set the board aside and move to preparing the project box.

Photo 5a Photo 5b


Preparing the Project Box

Step 6. Drilling the lid and the bottom of the box


Note that Photos 6a-c show the veiw from the underside of the project box lid.


Photo 6a: Cut out the drilling template and place it in the underside of the project box lid. Using a hammer and a sharp, pointed instrument such as a large needle or a punch, mark the centers of the4 holes on the template.


Photo 6b: Remove the template. Drill 3/32-in starter holes at each of the locations that you marked.


Photo 6c: Drill the starter holes to 1/4-in size.

Photo 6a Photo 6b Photo 6c


Step 7. Adding the label


Photo 7a: Trim around the black border of the lid label. A stencil or razor knife with a straightedge will help to get straight cuts, but sharp scissors will also serve.


Photo 7b: Pull the backing off one of the laminate sheets, and lay the sheet, sticky side up, on a table. Carefully place the lid label, label side down, onto the sticky side of the laminate sheet. In order to avoid getting air bubbles, apply the shorter edge of the label first and gradually push it down onto the laminate with a finger.


Photo 7c: Remove the backing from the other laminate sheet and carefully apply it, sticky side down, to create a sandwich of the two laminate sheets with the label in the middle. Use the technique described above to avoid getting air bubbles. When the laminate is in place, rub a finger over the laminate and around the edges of the label to ensure a good seal. Finally, use a stencil or razor knife or sharp scissors to trim the excess laminate from around the label. The completed label with laminate applied and trimmed is shown in Photo 7c.


Photo 7d: Use a 1/4-in hole punch to punch out the 1/4-in holes on the label as shown in Photo 7d. If you don't have a hole punch, the point of a sharp knife can be used to carve out the holes. Don't worry if some edges are ragged. These will be covered by the components later.


Photos 7e-g: Now it's time to glue the label to the top of the lid. First cut the 2-in section of plastic tubing into two 1-in pieces. For glue, use rubber cement or other repositionable adhesive. Spread the adhesive over both the lid as shown in Photo 7e and the under side of the label (not shown). Place the label in position on the lid, and align it using the two pieces of plastic tubing pushed through diagonally opposite holes as in Photo 7f. Flatten the label by rubbing a finger over it and hold in position for a minute or so to insure adhesion. Then carefully remove the plastic tubing to avoid shifting the position of the label. Any glue that extends beyond the edge of the label can be rubbed off with a finger. If there is glue smeared on the label that can't be rubbed off, use a mild solvent such as denatured or rubbing alcohol and a soft, clean cloth to clean the label. Finally, place the label under a stack of books or other weight to press it for a few hours. When completed, the lid with label should look like Photo 7g.


Photo 7h: Check the under side of the lid to see if portions of the label overlap any of the 1/4-in holes. If so, use a stencil knife, razor, or knife blade to trim the label back to the boundaries of the hole. This will make it easier to insert components later.

Photo 7a Photo 7b Photo 7c Photo 7d
Photo 7e Photo 7f Photo 7g Photo 7h


Adding Components to the Lid of the Project Box

Step 8. Adding the jacks


Photos 8a,b. Starting with the lid oriented as shown in Photo 7g above, flip the lid over so that the Input and Chain holes are on the right-hand side as you look down at the under side of the lid. Mount the two RCA jacks on the right-hand side as shown in Photo 8a. Note that the side lugs are oriented to extend toward the center of the lid. Photo 8b shows the lid from above with the RCA jacks mounted.


Photos 8c,d: Mount the two 3.5mm stereo jacks in the other two holes as shown in Photo 8c. Orient the side lugs toward the center of the lid. Photo 8d shows the upper side of the lid with the components mounted.

Photo 8a Photo 8b Photo 8c Photo 8d


Adding the Wiring

Step 9. Connecting the red and white wires to the lid


Photos 9a: Cut a 1.5-in section from the free end of each of the red and white wires that you mounted to the PCB earlier. Strip the wires back by 1/4-in on each end. Connect the red wire between the center lugs of the RCA jacks, and connect the white wire between the side lugs. Don't solder yet, as there are other wires to connect.


Photos 9b: Strip 1/4 in from the free end of each of the red and white wires connected to the PCB. Orient the PCB with respect to the lid as shown in Photo 9b. Connect the red wire to either of the center lugs of the RCA jacks, and connect the white wire to either of the side lugs.

Photo 9a Photo 9b


Step 10. Connecting the remaining wires to the lid


Photos 10a: The blue, green, and yellow wires will be connected to the stereo jacks on the lid. For the purposing of identifying connection points, we'll use the lug numbering scheme shown in Photo 10a. Go ahead now and strip back the free ends of all the blue, green, and yellow wires by 1/4 in.


Photo 10b: Start with the set of yellow, blue, and green wires from holes I5,6,8 of the PCB. Connect the green wire to lug 1 of the stereo jack, the blue wire to lug 2, and the yellow wire to lug 3 as shown in Photo 10b.


Photo 10c: Connect the remaining three yellow, blue, and green wires to the other stereo jack. As before, connect the green wire to lug 1 of the stereo jack, the blue wire to lug 2, and the yellow wire to lug 3 as shown in Photo 10c.


You may now solder all the connections on the lid.

Photo 10a Photo 10b Photo 10c


Completing the Assembly

Step 11. Wiring the battery holder and completing the assembly


Photo 11a: Insert the PS2501-4 quad optocoupler into the 16-pin socked on the board. Note the location of the white dot on the chip and the position of the white dot relative to the board. When inserting the IC, make sure all 16 legs are inserted into their respective holes. Then push down firmly with as nearly equal force as possible across the surface of the chip to seat all the pins at the same time.


Photo 11b: Seat the lid on the bottom of the project box and then screw in the corners.

Photo 11a Photo 11b


Jumper cable for breadboard circuits


bb_065.jpg (87501 bytes)

The jumper cable is only needed if connecting the Opto Switch 2 to a breadboard circuit, such as the Multi-Trigger Breadboard. Otherwise, skip to the operating instructions.


Strip 1/8" from each of the red and black wires.

bb_065.jpg (87501 bytes) Remove the collar from the female RCA connector. Then feed the red wire through the shorter solder lug as shown.
bb_065.jpg (87501 bytes) Solder the red wire to the lug.
bb_065.jpg (87501 bytes) Feed the black wire through the longer lug and solder it.
bb_065.jpg (87501 bytes) Clip the ends of the wires and then crimp the tabs around the wires.
bb_065.jpg (87501 bytes)

Screw the jacket on and then strip the wires on the other end about 1/8".


This completes the assembly of the Opto Switch 2. Go on to Operation.




Assembly instructions for other kits




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