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Assembly and Operating Instructions for Kits


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Assembly Instructions for the Multi-Trigger with PCB and Enclosure Kit (MTE-PCB, rev.4)


Assembly instructions for other kits


These instructions are for revision 4 of the kit. You can find the revision number printed on the PC board. Click on the image below to see the revision number.


PCB for Multi-Trigger



What you need

Parts guide (opens in new tab or window)

A helpful reference (includes circuit schematic)

Soldering the fixed-value resistors to the PCB

Soldering the IC sockets to the PCB

Soldering the capacitors to the PCB

Soldering the semiconductors to the PCB

Preparing the photogate cables

Preparing the microphone cable

External input cable (optional)

Preparing the trigger cable

Drilling holes in the project box lid

Adding the components to the project box lid

Wiring the box lid

Soldering the box lid connections

Connecting to the PCB

Completing the assembly


Operating manual (opens in new tab or window)


About the images: Clicking on any image will open a larger version on top of the page. If you prefer to have the larger images open in a different tab or window, right click on the image and make the appropriate selection.


What you need


PCB for Multi-TriggerThese instructions show how to prepare and use the PC board and project box enclosure for the Multi-Trigger. The MTE-PCB kit comes complete with all the parts needed for assembly of a working Multi-Trigger on a PC board enclosed in a project box. Also included are the parts to prepare microphone and photogate cables and to modify an existing trigger cable for connection to the project box.


The PC board is shown to the right. Click on it for a larger view. You'll see that the locations for the components are labeled with symbols like R1, C1, etc. This makes it easy to find where to place the components. You'll need to solder the components to the back (non-printed side) of the PCB. We'll provide guidelines for getting good solder joints, but we recommend that you have previous experience soldering on a PC board. With soldering, you can't make changes easily like you can with a breadboard. If you solder something in the wrong place, repair can be time-consuming.


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


For soldering

  1. 15-30 W soldering iron (with a new or pointed tip) and solder
  2. Wire stripper (photo below)

  3. A small diagonal cutter (photo below) makes it easy to trim the legs of the components after you solder them to the PCB, but other kinds of snipping tools such as scissors may work.

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

  5. A heat sink (photos below) protects heat-sensitive components while soldering.

  6. A desoldering tool (photos below) helps in clearing solder from a hole. The cylindrical type works better than the bulb.

  7. A magnifying glass is used to inspect solder joints.

  8. A lighter or matches to shrink heat-shrink tubing

  9. Hot glue gun

    Wire cutters and stripper

    Small diagonal cutter

    diagonal cutter

    Needle-nose pliers

    needle-nose pliers

    Heat sinks

    heat sink clip heat sink clip

    Desoldering tools

    desoldering tool desoldering bulb


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.


For the project box

  1. Drill motor and bits to drill holes in the project box lid. Bit sizes are 3/32", 1/8", 1/4", 9/32", and 5/16". (For metric equivalents in millimeters, multiply by 25.4.) You can substitute a 1/8" bit for the 3/32" one. You can get by without the 9/32" bit by drilling a 1/4" hole and filing it larger.
  2. Hammer, punch (or nail), small round file
  3. Wrenches or sockets to tighten components onto the project box

Parts guide


Click here for a detailed, illustrated list of all the parts you'll need. You can use this list to identify the parts and make sure you have them all.


A helpful reference


It will be helpful to print this pdf document for reference while you work. There are lists of component placements and jumper wire connections. For those who like to use circuit schematics, there's a complete schematic of the circuit.


Soldering the fixed-value resistors to the PCB


100k-ohm resistorIf you don't have your soldering iron heated up, do that now, because you'll be soldering before long. You'll be doing some detailed soldering work, so an iron with a good tip will make it easier. Let's start with R1, a 100-kohm resistor. See the photo to the right, and refer to the Parts Guide as needed for parts to come. The resistors are identified by the sequence of 3 colored bands, read from left-to-right. (The 4th, gold band indicates that the actual value of the resistance is plus or minus 5% of the value given by the color code.) For the resistor shown to the right, the bands are brown-black-yellow.

  1. Insert the legs of resistor R1 over the rectangular space labeled R1 on the PCB. See Figure 1. (Click on it for a closeup view.) You can flip the resistor either way in the holes; the orientation doesn't matter for resistors, since resistors work the same no matter which way current flows in them.

  2. Push the resistor in until it's flush with the surface of the PCB. Then flip the PCB over. Figure 2 shows the legs protruding from the back of the board.

  3. Next you'll solder. Tin the tip of the soldering iron by melting some solder on it. Then bring the point and the solder down to one of the holes where the resistor protrudes as in Figure 3. Melt some solder around the base; it doesn't take much. The solder should flow down into the hole around the leg of the resistor to make a good electrical joint. Now solder the other leg.

  4. Turn the board over to verify that solder filled the holes. See Figure 4. If you don't see that solder melted through to the upper side, it's probably a good idea to melt some more solder into the hole from the back of the board.

  5. When your solder joints are complete, you can snip off the legs of the resistor down to the solder joint or you can wait to snip legs until after you've added more components.

inserting R1 R1 from back of PCB Soldering a leg of the resistor R1 from back of PCB
Figure 1. Resistor R1 inserted into dedicated space on PCB Figure 2. Legs of resistor R1 protruding from back of PCB Figure 3. Soldering a leg of the resistor Figure 4. Inspecting the finished solder joints


Something to be aware of before you do any more soldering is that there are two kinds of holes on the board: solder holes and via holes. The solder holes are for the component legs. The via holes, which are smaller than the solder holes, are places where there are connections between the upper and lower conducting layers of the board. To see what we mean, click on Figure 5, which shows a small section of the board. The via holes have been circled in yellow. Don't try to solder components into via holes. If, however, you get solder in a via hole, don't worry about it.
  1. Your kit is supplied with a total of 15 fixed-value resistors. One of these will be soldered directly on the project box enclosure rather than the PCB. This is R0, a 1-kΩ resistor. Since you've already soldered R1 to the board, that leaves 13 resistors to solder to the PCB. Go ahead now and solder the remaining fixed-value resistors. When you've finished soldering the resistors, your board should look similar to Figure 6.
via holes board with all resistors
Figure 5. Via holes (circled in yellow) and solder holes Figure 6. PC board with fixed-value resistors mounted


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Soldering the IC sockets to the PCB


The 8-pin and 14-pin IC sockets will be used to seat the 555 and 556 timers. The latter won't be added to the sockets until later, since the ICs can potentially be damaged by heat.

  1. See Figure 7. Note that the socket has a notch on one end. You'll line this notch up with the one on the PCB when you seat the socket into the board.

  2. Place the 8 pins of the socket into the corresponding holes on the PCB as shown in Figure 8.

  3. Turn the board over and bend the pins down to the side to hold the socket in place as shown in Figure 9.

  4. Solder the 8 pins to the board. The finished result is shown in Figure 10. Check with a magnifying glass to make sure there are no solder bridges or hairs between pins. If so, remove them by running the tip of the soldering iron between the pin.

  5. Solder the 14-pin socket to the board similar to how you did the 8-pin socket.

8-pin socket notch seating the 8-pin socket Crimping the 8-pin socket 8-pin socket soldered to PCB
Figure 7. Notches on the socket and the PCB Figure 8. 8-pin socket seated on PCB Figure 9. Crimping the pins of the 8-pin socket Figure 10. 8-pin socket soldered to PCB


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Soldering the capacitors to the PCB


There are two kinds of capacitors, ceramic and electrolytic. We'll start with the ceramic capacitors. There are 6 of these; they all have a disc shape and are orange or yellow in color. A number on the disc identifies the capacitor. The capacitor in Figure 11, for example, has the number 473. From the Parts Guide, you can determine that this is a 0.047-μf capacitor.


  1. Ceramic capacitors, like resistors, are non-polar. So it doesn't matter if you flip them one way or the other other in the solder holes. Slip the ceramic capacitors in the holes now as shown in Figure 12. Bend the legs over on the back.

  2. Turn the board over and solder the capacitor legs like you did the resistor legs.

  3. There are two electrolytic capacitors. These have cylindrical metal cases with the value of the capacitance printed on them. See the photo of a 10-μf capacitor in Figure 13. These capacitors are polar; that is, they have a positive and negative side. Therefore, there's only one way to mount them in the PCB. You'll see that the locations of the positive and negative sides for an electrolytic capacitor are marked on the PCB. For example, note the negative (-) sign for C3 in Figure 14. The corresponding negative side of the capacitor has a negative sign--it's a hollow rectangle--printed on one side. This is also the side with the shorter leg. Place the two capacitors on the board now as shown in Figure 15. Then turn the board over and solder the legs.

  4. If you haven't snipped off the legs of the components protruding from the back, do that now. Snip them at the solder joint. You don't want to have any legs that can be bent over and touch other legs to create short circuits.

0.0047-uf capacitor mouting the ceramic capacitors 10-uf capacitor location of C3 with polarity indicated
Figure 11. Ceramic capacitor Figure 12. Mounting the ceramic capacitors Figure 13. Electrolytic capacitor Figure 14. Polarity for C3 is indicated on the PCB
electrolytic capacitors on PCB      
Figure 15. Electrolytic capacitors seated on PCB (polarity indicated)      


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Soldering the semiconductors to the PCB

  1. There are 5 semiconductors, one transistor and four SCRs. They look alike except for the lettering on the face. You'll mount the transistor first. Look for the part that says PN2222A on the face. Slip it into the PC board as shown in Figure 16. Note that the flat side faces toward the inside of the board. This orientation is required for correct operation of the circuit.

  2. Soldering the semiconductors takes special care, because the components can be damaged by getting too hot. A way to bleed off excessive heat is to use a heat sink as shown in Figure 17. The heat sink is just a metal clip that grasps the leg to be soldered. The alternative to a heat sink is to solder quickly. If you find yourself taking too much time, wait a while to allow the component to cool before continuing. Solder on the back side like you did for the other components. Avoid the temptation to linger while soldering; the hole will fill before you know it. Turn the board over to check the other side to make sure that too much solder hasn't bled through.

  3. When you finish soldering the three legs, inspect carefully for solder bridges on both the front and back sides of the board. The legs of the transistor are so close together that solder bridges are a likelihood. Inspect under a magnifying glass for fine solder hairs. See Figures 18 and 19 for how your finished solder joints should look.

mounting the PN2222A transistor Using a heat sink on a transistor leg Inspecting for solder bridges Transistor soldered to PCB
Figure 16. Mounting the PN2222A transistor. Note the flat side. Figure 17. Using a heat sink on a transistor leg Figure 18. Inspecting for solder bridges Figure 19. Transistor soldered to PCB
SCR for photogate output (front view) Sound trigger output SCR Delay unit output SCRs  
Figure 20: D1 SCR positioned on board Figure 21: D2 SCR Figure 22: D3 and D4 SCRs for instant and delayed outputs  
  1. Now let's move on to the SCRs. These have EC103D written on the face. Insert the legs of an SCR into the D1 location as shown in Figure 20. Make sure the flat side faces toward the 8-pin socket. The flat side also coincides with the symbol printed on the board. Solder the legs of the SCR as you did for the transistor.

  2. Position SCR D2 for the sound trigger as shown in Figure 21 and solder into place.

  3. Position SCRs D3 and D4 for the instant and delayed outputs as shown in Figure 22 and solder into place.

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Preparing the photogate cables


Your kit includes parts for two types of photogate cables. What we call SPG1 has an individual emitter and detector. This is useful when you need large separations between the emitter and detector. The SPG2 cable uses an interrupter, which houses the emitter and detector in a U-shaped plastic housing about 5/8" apart. This is useful for triggering on the passage of a drop of liquid. Assemble at least the SPG1 cable now. You can wait to assemble the SPG2 cable later if you prefer.


About the SPG1 cable


IR LED/PT connectionsThe SPG1 cable uses a separate infrared LED emitter and infrared phototransistor (PT). The LED is the component with a blue case, and the PT has a clear case, as shown to the left. For both components, one leg is shorter than the other. The shorter leg is positive on the PT, while on the LED, the longer leg is positive. The figure to the right, courtesy of a helpful DIYer, provides a visual display of the connections that you'll be making to the infrared LED and phototransistor.


Here are the parts you'll need:
3-conductor cable, 3-ft length
Yellow hookup wire, 1.5-ft length
Infrared phototransistor (clear case)
Infrared LED (blue case)
3/32" heat shrink tubing (HST), 4" length


stripping the 3-conductor cable

stripping the yellow wire

twisting the red and yellow wires

Stripping the wires


Cut the 6-ft 3-conductor cable supplied with your kit into two 3-ft sections. You'll use one section for each of the SPG1 and SPG2 cables.


At one end of a 3-ft section of cable, strip the outer casing back by 9 inches. This will reveal the three inner conductors, colored red, black, and green. Strip each of these conductors back by ¾ inches. This will expose conductors that will be wrapped around the appropriate component legs later. See Photo 1 showing the cable after stripping.


Strip both ends of the yellow hookup wire back by 3/4 inches. See Photo 2.


Twist the red wire and one end of the yellow wire together tightly, as shown in Photo 3.

adding the heat-shrink tubing

Fitting the heat shrink tubing and making connections


Cut the heat shrink tubing (HST) into four 1" pieces. Place one piece over each wire (black, green, jumper, red+yellow) as shown in Photo 4, and slide it back onto the wire. Be on the lookout for pieces falling off if wires are held upside down.


Now it's time to make connections by wrapping the wires around the legs of the PT and LED. When wrapping, try to get at least two complete turns; more are better. Before twisting any wires together, make sure the HST for that wire is still present and hasn't fallen off.


Make the following connections by twisting the wires around the component legs.

  • Twist the green wire tightly around the longer leg of the PT (clear case) and the black wire of the 3-conductor cable around the shorter leg of the LED (blue case). (See Photo 5.)
  • Twist the combined red+yellow wire around the longer leg of the LED and the other end of the yellow wire around the shorter leg of the PT.

When done, your connections should look like those in Photo 6.

soldering the legs

Soldering the connections


Trim any stray wire strands on the connections so the heat shrink tubing will slip over them.

It's a good idea to place a metal clip to serve as a heat sink between the head of the PT or LED and the leg where you will be soldering. (See Photo 7.) This will help avoid damage from overheating. If you don't use a heat sink, complete the soldering quickly to minimize heat buildup.


The completed soldering job is shown in Photo 8.


slipping on the HST



After soldering, slide the heat shrink tubing over each of the solder joints so that the legs of each component are insulated from each other. (See Photo 9.) Keep the pieces about 1/8” away from the component heads to protect them from overheating when the tubing is heated.

Using a lighter or a match, move the flame smoothly back and forth along the entire length of the tubing, with the tip of the flame just beneath it. (See Photo 10.) If you hold the flame too long in one spot or too closely to the tubing, you will notice smoke. If this happens, lower your flame and continue moving it back and forth.

The tubing will visibly shrink and will be acceptably tight-fitting after only 10-15 seconds of heating.


The aligned components are shown in Photo 11.



About the SPG2 cable


For this cable, the IR emitter and detector are housed in the U-shaped piece shown to the left. In addition to this piece, you'll need a 3-ft length of 3-conductor cable and a one-inch piece of hookup wire. For the latter, cut a 1-inch piece from one of the hookup wires included with your kit.

Stripping the wires


At one end of the 3-conductor cable, strip the outer casing back by 2". Then strip the individual conductors back ¼". This will yield short lengths of wire that will be easy to tack solder to the short interrupter legs. See Photo 11.


Strip all the insulation from your one-inch piece of hookup wire. (no photo for this) For the latter, cut a 1-inch piece from one of the hookup wires included with your kit.

Soldering the connections


interrupterThe symbols and on the top view of the figure of the interrupter to the right refer to the LED and phototransistor (PT) respectively. The numbers refer to the legs on the underside (not shown).


You'll be making the following solder connections.

  • black wire to leg 2
  • green wire to leg 3
  • 1" piece of hookup wire between legs 1 and 4
  • red wire anywhere along the length of the 1" hookup wire

The interrupter has short legs, so you won't be able to wrap the photogate cable wires around the legs. Instead, you will need to hold the wire to the leg and tack solder the two parts together. A clamp to hold the interrupter may be useful for maintaining alignment while you are soldering. Since you won't be able to use a heat sink, minimize the amount of time that the soldering iron is in contact with the leg. We recommend melting some solder on the tip of the iron first. Then, while holding a wire to a leg, touch the liquid solder to the pair and let just enough solder flow to make a bond. Avoid touching the body of the interrupter to keep from melting the plastic. See Photos 12 - 14.


After soldering each connection, remove the soldering iron and hold the wire to the leg for a few seconds to allow the solder to solidify.


Check to make sure that you don't have any solder bridging between legs. If you do, you'll need to melt the solder to clear the bridge. See Photo 15 for a completed soldering job.


If you're concerned about the wires breaking off of the interrupter legs from use, you can cover the base of the interrupter with hot glue but you may want to wait to do that until after you've tested the cable.

Adding 3.5mm stereo connectors to the cables

The photogate cables will connect to the project box enclosure with 3.5mm stereo male connectors. Therefore, you need to add one of these connectors to each of the photogate cables. The process is described below.

3-conductor cable with ends stripped for connector

Select one of the two photogate cables to start with. Unscrew the jacket of one of the 3.5mm stereo male connectors and push it onto the cut end of the cable. Then strip the gray insulation back about 1/4" and the individual wires about 1/8" as shown in Photo 16.
The terminals of the connector are numbered in Photo 17. The black wire will connect to 1, the green wire to 2, and the red wire to 3. If you have trouble getting all the strands through a hole, you can clip off the strands that won't fit.
Photos 18 and 19 provide two views of the assembly with connections soldered and stray strands clipped.
Crimp the metal tabs around the cable and screw on the jacket to complete the assembly shown in Photo 20.
Photos 21 and 22 show the completed cable assemblies. The cables will connect to the corresponding 3.5mm stereo jack on the enclosure once that part of the project is complete.


Preparing the microphone cable


Here's what you'll need for the microphone cable:

  • 3-ft length of 2-conductor cable
  • 3.5mm mono connector (male)
  • 2 inches of 3/32-in heat-shrink tubing
  • 3 inches of 3/16-in heat-shrink tubing
  • piezoelectric disc

Begin by cutting the 3/32" heat-shrink tubing into two 1-inch lengths and slip them onto the red and black wires of the piezo disc. Then strip the ends of the wires about 3/4".

From one end of the gray 2-conductor cable, strip the gray insulation back 3/4". Then strip each of the red and black wires 3/4".
Twist the red wire of the piezo disc around the black wire of the 2-conductor cable. Likewise, twist the black wire of the disc around the red wire of the cable.
Solder the connections.
Slip the heat-shrink tubing over the soldered wires and run a lighter or match flame under the tubing to shrink it but not so close as to burn the tubing.
Slip the 3" section of 3/16" heat-shrink tubing onto the cable and over the spliced connections. Heat shrink it into place.
Remove the jacket from the 3.5mm connector and slip it over the cut end of the cable. The threaded end must be toward the cut end of the cable. Strip back the gray insulation on the free end of the cable about 1/4" and then strip the insulation on the red and black wires about 1/8".
Insert the stripped wires into the holes on the terminals of the 3.5mm mono connector. The red wire goes in the shorter terminal. Don't crimp the metal tabs around the cable yet, as this will cause the insulation to melt when you solder.
Solder the connections. Since there's so much metal, it will take some time for the soldering iron to heat the metal. Hold the tip of the iron flat on the metal to heat it up in the vicinity of where you want to solder. Touch the solder to metal and wait for it to start flowing. This is the way to ensure a good electrical connection rather than a cold solder joint.
Clip off any stray wires and then crimp the metal tabs around the gray cable.

Screw on the jacket, and your microphone cable is complete. The cable will connect to the corresponding 3.5mm mono jack on the enclosure once that part of the project is complete.


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External input cable (optional)


There is another 3.5mm mono male connector in your kit. This connector is for an external input. This input allows the delay unit of the Multi-Trigger to be used with any trigger circuit or, in fact, any circuit that provides a short circuit output. The external input can also be used with a simple contact trigger such as the one shown here. If you will be using an external input with the Multi-Trigger enclosure, you'll need to provide a 2-conductor cable. If you'll be using a trigger circuit as the external input, just use the output cable that came with that circuit. Connect the extra 3.5mm mono connector to one end of the cable like you did for the microphone cable above. The other end of the cable will connect to the output of your external circuit. A completed external input cable that could be connected to the output of a circuit on a breadboard is shown to the left.



Preparing the trigger cable

  1. In order to prepare a trigger cable to connect your Multi-Trigger enclosure to a flash unit or camera, you need to start with a cable such as one of the four shown in Figures 24 - 27. These 2-conductor cables have a connector for the flash or Opto-Switch on one end and bare wires on the other end. The 2-conductor cable is supplied with your Multi-Trigger kit, but the connector for flash or Opto-Switch is not supplied, since that will depend on your flash and camera equipment. We're assuming that you've already prepared one of the cables shown in Figures 24 - 27 as you proceed with the instructions below.

A male RCA connector will be soldered to the bare wires on the cable. Continue below the photos to prepare the cable.

PC cable to connect flash to breadboard Adapter to connect flash foot to breadboard Cable to connect Camera Opto-Switch to breadboard PC cable for Vivitar 283

Figure 24. PC cable to connect flash to breadboard

Assembly instructions

Figure 25. Adapter to connect flash foot to breadboard

Assembly instructions

Figure 26. Cable to connect Camera Opto-Switch to breadboard

(Assembly instructions are part of the Camera Opto-Switch assembly.)

Figure 27. Cable to connect a Vivitar 283/285 flash to breadboard

(Use the assembly instructions for a PC cable, but substitute the Vivitar 283 connector for a PC connector.)

  1. Removing the jacket from the RCA plug

    Unscrew the black jacket from the RCA plug as shown to the right.

  2. For whichever of the four cables shown in Figures 24-27 that you're preparing, cut off the free red and black wires where they extend from the gray insulation. Then push the black jacket over the cable as shown in Figure 28. If you find the fit too tight, snip off part of the collar that grips the cable. Once you have the jacket on the cable, strip back the gray insulation 1/4 inch. Then strip the red and black wires 1/8 inch.

  3. Important: Don't crimp the metal tabs around the gray insulation before soldering. If you do, the heat of soldering can melt the insulation. Now thread the red wire through the smaller of the two solder lugs and solder it. Then solder the black wire to the longer lug. This lug can take a lot of heating since there's so much metal. Make sure that it gets hot enough for the solder to flow freely. The metal takes a while to cool down, so don't touch it for a while. After you've finished soldering, examine the connections for stray wire strands. Clip off any that you find. Figure 29 shows the completed solder joints.

  4. Crimp the metal tabs around the gray cable and screw the jacket on. The completed connector is shown in Figure 30.

  5. A completed cable for connection from the Multi-Trigger enclosure to a flash unit is shown in Figure 31.

  6. Two male RCA connectors are supplied with your kit so that you can prepare a second trigger cable. For example, you could have one trigger cable for your flash unit and another for an Opto-Switch.

Stripping wires in preparation to add RCA connector RCA plug connected to the red and black wires RCA plug connected to cable PC cable ready to connect to PCB
Figure 28. Stripping wires in preparation to add RCA connector Figure 29. RCA plug connected to the red and black wires Figure 30. RCA plug connected to cable Figure 31. PC cable ready to connect to PCB


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Drilling holes in the project box lid

  1. The template is sized to fit snugly within the underside of the project box lid (that is, on the interior side of the box). Position the template inside the lid as shown in Figure 32. Then use a nail or punch to mark the positions of the centers of the holes to be drilled.

  2. Remove the template and drill the holes. We recommend drilling small pilot holes first, for example, 3/32" or 1/8". The plastic has a tendency to grab the bit, so hold the plastic securely. We've found that a spade bit works best for drilling the quarter-inch holes. If you don't have a 9/32" bit, you can use 1/4" and then file the hole to a larger diameter for the pushbutton.

  3. Use a round file to clean up any burrs around the holes. The lid with holes drilled is shown from underneath (Figure 33) and from above (Figure 34).
template in underside of project box lid Project box lid from underside after holes drilled Top of project box lid after holes drilled  
Figure 32. Template placed in underside of project box lid Figure 33. Underside of project box lid after holes drilled Figure 34. Top of project box lid after holes drilled  


Adding the components to the project box lid

  1. LED holderWe recommend adding the three red LEDs first, since people tend to have difficulty getting the holders to snap into place. The LED mounts have two parts, which we will call the collar and the ring. (See photo to the right.) The collar is first slipped into a hole on the project box from the top side toward the interior of the box and snapped into place. Then the LED is pushed up into the collar from below and snapped into place. It's important that you push the LED all the way up until its base is flush with the base of the collar. It may take quite a bit of extra force to push it the last bit of the way. You'll know it's in when it snaps. If you don't push the LED in all the way, it will be loose in the collar. See Figure 35 showing two of the LEDs after being snapped into place. Note how the bottom of the red case sits down inside the collar. Also see Figure 36 which shows the LEDs from the top of the box. Note how far they extend above the collar.

  2. Once you have the LEDs snapped in, push the rings over the collars from below. See Figure 37. The completely assembly of the three LEDs is shown in Figure 38.

LEDs inserted into collars from below LEDs from above Completed LED holder assembly  from below Completed LED assembly from above
Figure 35. LEDs inserted into collars from below Figure 36. LEDs from top of project box Figure 37. Completed LED holder assembly from below Figure 38. Completed LED assembly from above


For the remaining components, we don't provide step-by-step photos. The completed assembly of all components on the project box lid is shown in Figures 39 and 40 from below and above, respectively.

  1. Remove the nut from a 3.5mm jack, insert the jack through the box lid from below, and screw the nut back on. Needle-nose pliers can be helpful in tightening the small, round nuts. There are three of these 3.5mm jacks to mount. The black one is a stereo jack; the others are mono jacks. Be sure to get the black one in the correct hole.

  2. Remove the nut from the AC/DC input jack, insert the jack through the box lid from below, and screw the nut back on. You can use a wrench on this nut.

  3. Remove the nut and lock washer from the pushbutton, insert the pushbutton through the box lid from below, slip on the washer and screw the nut back on.

  4. For an RCA jack, remove the nut and metal tab from the jack, insert the jack through the box lid from above, slip the metal tab and washer on under the box lid, and screw the nut on. While you can use a wrench to tighten these, keeping the jack from turning while tightening requires a strong grip on the jack.

  5. The switches have a retaining ring with a key tab, a washer, and a nut. Remove all three and then insert the switch from below. Orient the slot on the threads to be on the same side as the 3/32" key hole. Then slip the retaining ring on so that the key tab slips into the 3/32" hole. Slip on the washer and nut and tighten. Note that there are two different types of switches, SPST (2 contacts) and SPDT (3 contacts). The SPST switch is the On-Off switch in a corner of the box.

  6. The potentiometers also have key tabs but these are on the body of the pot. Remove the washer and nut from a pot, slip it in from below and orient it so that the key tab passes up through the 1/8" key hole. Then put on the washer and nut and tighten. Note the locations of the 5 pots according to value.

Components mounted on project box lid (view of underside) Components mounted on project box lid (view of the top)  
Figure 39. Components mounted on project box lid (view of underside) Figure 40. Components mounted on project box lid (view of the top)    


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Wiring the box lid


Some of the components on the box lid will be hardwired to each other before making connections. Make connections for now but don't do any soldering yet.

  1. There is one resistor that is connected between two components on the lid. This is the 1-kΩ resistor labeled R0 in the Parts List. See Figure 41 for the placement of the resistors. You'll need to clip the legs of the resistor to make it fit. Note that the resistor is connected to the shorter leg of the right LED. Something to help in spiraling the resistor legs around the LED legs is to wrap the resistor legs around a small nail first. Figure 42 shows this being done with a wire.

  2. Use the 2-ft length of white wire to make all the ground connections. While the color has nothing to do with how the circuit operates, using consistent colors will help you to keep track of what you're doing. You'll be clipping off lengths of wire and making the connections shown in Figure 43. If you size the lengths accurately, you'll have just enough of the white wire. Refer to Figure 43 and note the following:

    1. A wire is connected to the center lug of the AC/DC jack in the lower right.

    2. Two wires are wound around the shorter leg of the center LED.

  3. We'll use the red wire for +9V connections. See Figure 44 for the connections to make. Note the following:

    1. The longer leg of the right LED has two red wires connected to it. See Figure 45 for a closeup. This also shows the white wires wrapped around the shorter leg of the center LED.

    2. For the left LED, two red wires are connected to the longer leg. See Figure 46.

  4. There are four more wires to add to the box. Two of them are yellow and two are blue. See Figure 47 for connections.
  5. Looking down, it may difficult to see the connections to the external input jack (the cream-colored jack). See Figure 48 for clarification. Two white wires are connected to lug 1 on the side, a blue wire is connected to lug 2, and a yellow wire is connected to lug 3.
Resistors connected on box lid Wire wrapping Ground wires added +9V wires added
Figure 41. Resistors connected on box lid Figure 42. Wire wrapping Figure 43. Ground wires added Figure 44. +9V wires added
Connections to the right LED Connections to the left LED Box lid with yellow and blue wires Connections to the external input jack
Figure 45. Connections to the right and middle LEDs Figure 46. Connections to the left LED Figure 47. Box lid with yellow and blue wires Figure 48. Connections to the external input jack


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Soldering the box lid connections


It's about time to start soldering. Here are some important tips about soldering in addition to those given previously.


Soldering to the legs of the LEDs: These components can be damaged by excessive heat; therefore, it's a good idea to clip a heat sink to the leg when soldering.


Soldering the switches: Don't hold the soldering iron on the switch lugs too long, as the plastic can melt and break the internal contacts.


Soldering the 3.5mm jacks: The lugs on these jacks bend and break easily. Go easy on them.


Soldering the AC/DC jack: Be very careful not to get too much solder on the lugs so that the solder drips down, particularly on the center lug. If the solder drips down, it can create a dead short between the positive and negative power terminals.


Soldering the RCA jacks and pots: These components have a lot of metal and will take longer to heat up than the other components will. You're not likely to damage a pot but you could soften the plastic in an RCA jack.


About cold solder joints: If you don't heat the metal before soldering the wire, the solder may not bond with it and you can get an open circuit. You can't necessarily tell by looking that you have a cold solder joint. The best approach is prevention by using good soldering techniques. Hold the tip of the soldering iron flat against the metal surface that you're soldering to. Touch the solder to the metal nearby rather than to the soldering iron. When the metal is hot enough, the solder will flow. Flow enough solder on the connection to fill the hole and cover the connection, but don't leave the soldering iron on the metal any longer than it takes to flow the solder. Examine the connection under a magnifying glass. If the solder beaded up, you may not have a good connection.


For some of the figures in this section and the next, you can download full-page photos for printing to make it convenient to keep track of connections.

  1. Figure 50 shows the junctions circled in green that can be soldered now. If a junction isn't circled, don't solder it yet, because additional wires need to be added to jump to the PCB.

  2. Figure 51 shows where wires will be connected to jump to the PC board. Figure 52 shows the wires after being soldered in place. We recommend cutting each of the jumper wires to a length of 6 inches and using the colors shown in the photo. The hookup wire provided in your kit has been sized to insure that you'll have enough if you follow these directions. (The numbers 1-25 associated with the wires will be used in the next section to route the wire to the correct holes on the PCB.)
  3. Note the lug of the AC/DC jack circled in green and labeled B(-) at the lower right in Figure 52. You'll solder the black wire of the battery holder to this lug, but we recommend waiting until Step 5 of the next section to do that.
Junctions to solder on the box lid Connection points for external wires Jumper wires connected to box lid

Figure 50. Junctions to solder on the box lid

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Figure 51. Connection points for external wires

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Figure 52. Jumper wires connected to box lid

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Connecting to the PCB

  1. You'll need to decide on a physical arrangement that you're comfortable with when soldering the jumper wires to the PCB. Two possibilities are shown below. Figure 53 shows the PCB lying face up on a table in front of the box lid, which is propped up vertical. The advantage of this arrangement is that you can see the writing on the PCB. The disadvantage is that it's difficult to size the wires to optimum lengths. We prefer the arrangement shown in Figure 54 in which a clamp holds the PCB upside down above the box lid. If you don't have a clamp such as the one shown, you can still use this method if you have some means--perhaps another person--to hold the board while you solder. After you've soldered several wires, you'll find that the springiness of the wires will be enough to hold the board up. This upside-down method makes it easy to size the wires correctly. While you don't have the PCB labels to help you locate holes, we have an aid that will be described in step 3.

  2. If you use the method shown in Figure 53, you'll be able to be able to see the hole numbers on the top of the PCB corresponding to the wire numbers in Figure 52 above. Note that two holes aren't used, 22 and 23, and that one hole for a wire (25) isn't numbered. See Figure 55 for that hole.
  3. If you use the method shown in Figure 54, use Figure 56 to aid in routing wires to the correct holes. The figure has an overlay of the same numbers used for the wires in Figure 52.

  4. Before beginning soldering, there are a couple of things left to do:

    1. Snip the legs of the LEDs down far enough that they don't get in the way. Also, make sure the legs are separated and not shorting against each other.

    2. Insert the ICs into the sockets on the PCB. It's a good idea to discharge yourself by touching a grounded pipe or even the wooden leg of a table before handling the 555 and 556 timers. These are static-sensitive parts. Remember the notches in the socket? Well, there's a corresponding notch in the end of each IC. When you put an IC in a socket, the notches must be at the same end. Start with the 555 timer. Place it on the socket and pinch the pins gently if necessary to guide them into the holes. When all the pins are aligned, push down firmly on the IC to seat the pins. Repeat with the 556 timer.
  5. Go ahead now and solder the jumper wires from the lid to the PCB. Note that B(+) is for the red wire of the battery pack, but we recommend saving that connection for the next step. You might want to try placing the wires in their holes before soldering to see how everything is going to fit together. Also, you can trim down some of the wires to shorter lengths. This way, you'll have less wire to compress when you lower the assembly into the box.

  6. Decide how you want to position the battery holder in relation to the PC board. Then solder the red battery holder wire to B(+) on the PCB and the black battery holder wire to B(-) on the lid. See Figure 57 for the lug on the AC/DC jack to which B(-) is soldered. The inset shows the lugs numbered 1, 2, 3. Lug 1 is for the black wire, lug 2 for the white wire, and lug 3 for the red wires.

  7. Snip off any wires extending from the bottom of the PCB.
One possible arrangement for working on PCB connections Another possible arrangement for working on PCB connections PCB (top side) with overlay of numbered locations for jumper wires from the box lid PCB (bottom side) with overlay of numbered locations for jumper wires from the box lid
Figure 53. One possible arrangement for working on PCB connections Figure 54. Another possible arrangement for working on PCB connections

Figure 55. PCB (top side) indicating hole 25

Figure 56. PCB (bottom side) with overlay of numbered locations for jumper wires from the box lid

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Connections to AC/DC jack      
Figure 57. Connections to AC/DC jack      



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Completing the Assembly


See Figure 58 for how everything fits together in the project box. The battery holder can be held tight to the bottom of the box using the stick-on hook and loop strips provided. The PCB is held tight by the springy action of the jumper wires. Place a fresh battery in the battery holder before closing the box. Then gently work the lid down, compressing the wires gradually and making sure that they don't get pinched by the box lid. Use the 4 screws that came with the project box to hold down the lid.


When you have it all together, add the knobs and labels to the lid as shown in Figure 59.


Important note about labeling: The order of the INSTANT outputs is FLA CAM and of the DELAYED outputs is CAM FLA.


Here's an alternative to using the labels provided with the kit. Figure 60 shows a DIY label template courtesy of Erwin Stok of Stokware fotografie . He created his own template for all the labels on the box lid. Click on the Actual size links for either a pdf or jpg template that can be printed on the appropriate media for mounting. Stok recommends printing the template on self-adhesive sheets of white paper and then covering the paper with a piece of self-adhesive transparent film for protection. The final product is shown in Figure 61.


Seating the battery holder and PCB in the project box Multi-Trigger box with labels

Stok MTE-PCB template

Actual size pdf template

Actual size jpg template

Stok MTE-PCB box

Figure 58. Seating the battery holder and PCB in the project box Figure 59. Multi-Trigger enclosure with labels Figure 60. Label template courtesy of Erwin Stok, Stokware fotografie Figure 61. Template mounted on box lid




This section provides a run-through to test all the functions of the Multi-Trigger.


Power test

If you're powering the unit with either a battery or the optional AC/DC adapter, the power LED should go on when you flip the ON-OFF switch to the right. When using the AC/DC adapter, the battery will be bypassed if one is installed. This conserves your battery so that you can leave it in the unit all the time, available for when you need portable power.


Photogate test

Turn the PG SENS to the middle of its range. Plug in the photogate cable, preferably the interrupter cable since you don't have to mess with alignment for that one. Be sure to push it in all the way. The PG alignment LED should light indicating that the photogate is aligned and the beam is unbroken. Now run your finger through the interrupter. The PG LED should go out momentarily. If so, all is well to this point.


Now try the other photogate cable. Tape the emitter and detector down to a table a few inches apart pointing toward each other. When you get them aligned, the PG LED will go on. Run your finger between them, and the LED will flicker off. Now try turning PG SENS clockwise. At some point, the alignment LED will go out. What you've done is actually make the circuit so sensitive that it triggers spontaneously. If you turn the knob back a bit, you can set the photogate in its most sensitive working condition. You'll find that this setting depends on the separation of the emitter and the LED as well as the ambient light. In order to see this, move the emitter and detector about 6 inches apart and readjust the sensitivity as needed.


Delay unit test

Remove the photogate cable. Turn the COARSE DELAY pot all the way clockwise. Flip the INPUT selector switch to MIC and the Divide/10 switch (also called Delay Range) to the 0.5s position. Turn the Timeout all the way clockwise. Push the Test button. After a delay of about a second, the TRIG LED should turn on and stay on for about a second. Now rotate the Timeout all the way counterclockwise. When you push the Test button, you'll get the same delay as before, but the delay unit LED will flicker briefly. It won't be bright. The TIMEOUT pot adjusts the amount of time that the circuit is inactive after a triggering event. The range is from about 0.01 to 1.0 seconds. That's how long the TRIG LED remains on.


You can try adjusting the FINE DELAY; however, you probably won't notice a change in the delay. The greatest change possible with the FINE DELAY is less than a tenth of a second. Of course, a difference of that much would be quite noticeable in a high-speed photograph.


Now flip the Divide/10 switch to the 0.05s position. When you push the TEST button, there won't be noticeable delay. Flipping the switch had the effect of dividing the delay by 10. There's still a delay, though, and it would be noticeable if observing high-speed events.


Note that when you don't have a photogate or microphone cable connected to the box, the TEST button will only function if the INPUT selector is set to the MIC position.


Photogate with delay test

Now plug in one of your photogate cables again, and flip the INPUT selector to PG. You should get all the same results as above if you break the photogate beam instead of pushing the test button.


Delay unit with external input test

If you have an external trigger that you want to use with the Multi-Trigger and you've already prepared a cable for it, plug the cable into the external input (EXT IN) jack. The delay unit should function the same with an external trigger as it did with the photogate.


If you don't have an external trigger or haven't prepared a cable for it, you can still test the external input. Take the extra 3.5mm mono connector (male) and unscrew the plastic jacket. Insert the plug into the external input jack. With a paper clip, piece of wire, or other metallic object, short together the two bare terminals of the plug. This should trigger the delay unit the same way as pushing the test button. Remove the 3.5mm plug before continuing.


Test of flash outputs

Connect the trigger cable for your flash unit to the INSTANT FLA output. When you push the test button or run your finger through the photogate, the flash should discharge immediately. The coarse and fine delays, timeout, and delay/10 settings have no effect. Now move the flash trigger cable to the DELAYED FLA output. Now, the coarse and fine delays, timeout, and delay/10 settings should all work as they did in previous tests of the delay unit. Try turning the timeout all the way clockwise. In this position, the flash should be disabled for about one second after a triggering event. This is useful to avoid multiple exposures.


Test of sound trigger input

Remove the photogate cable and connect the microphone cable. Flip the input selector to MIC. Turn SND SENS to the middle of its range. Tapping the microphone or snapping a finger should trigger the delay unit and your flash the same as with the photogate.


Turn the SND SENS pot clockwise. At some point, you won't be able to trigger the unit anymore. Like PG SENS, the sound trigger becomes so sensitive that it holds the flash trigger circuit on, thereby making it unable to respond to triggering events. Turn the knob counterclockwise just a bit until the unit triggers again. This is the point of maximum sensitivity. Generally, it's best to keep SND SENS at the middle position unless you have an application that requires higher or lower sensitivity.


Test of camera outputs

Important: Don't connect a camera shutter or wireless controller directly to either of the CAM outputs. You must use a Camera Opto-Switch with these outputs.


If you're using a Camera Opto-Switch to trigger your camera, connect the TRIG jack of the Opto-Switch to either the INSTANT or DELAYED CAM output, and connect the shutter cable from your camera to the CAM jack of the Opto-Switch. (See your Opto-Switch instructions if necessary.) A triggering event should actuate your camera shutter. Note that the Opto-Switch will not function from a flash output.


This completes testing. If any of your tests failed, you'll need to open the box and check your connections. Make sure you don't have any short circuits. If you have questions, you may contact us and we'll do our best to troubleshoot by email.


Operating Manual




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