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Assembly and Operating Instructions for Kits


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Assembly Instructions for the PCB for the Multi-Trigger (MT-PCB1)


Assembly instructions for other kits





What you need

Parts guide (opens in new tab or window)

Soldering the fixed-value resistors to the PCB

Soldering the IC sockets to the PCB

Soldering the variable resistors to the PCB

Soldering the capacitors to the PCB

Soldering the semiconductors to the PCB

Soldering the LEDs to the PCB

Soldering the switches and jacks to the PCB

Soldering the cables to the PCB

Preparing the trigger cable

Operating the PCB Multi-Trigger


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What you need


PCB for Multi-TriggerThese instructions show how to prepare and use the PC board for the Multi-Trigger Kit, MT-PCB1. In addition to the MT-PCB1 kit, you'll also need a Multi-Trigger (MT). If you've already built a Multi-Trigger on a breadboard, you can transfer some of the parts from that circuit to the PCB. We're assuming that you've prepared the photogate cables for the Multi-Trigger as well as an output cable to connect to your flash or camera. (See Steps 10 and 11 of the Multi-Trigger assembly instructions.)


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.

  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 clipheat 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.


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. Also, you may find it helpful to print out the 4th page of this pdf document. It lists all the PCB components and their PCB labels. If you're into electronics, you may also wish to view the circuit diagram on page 2 to see how the components fit into 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
  1. Go ahead now and solder the remaining fixed-value resistors onto the board. There are 13 of them. (There is no R7.) Don't solder the five variable resistors yet; that will be in a later step. Something to be aware of 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. 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 all 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 Variable Resistors to the PCB

  1. There are 5 variable resistors (also called potentiometers or pots). Each has three legs and a knob that is rotated to adjust the resistance. Figure 11 shows the 10-k pot sitting on the PC board next to the area designated for it to be mounted. Go ahead and place the pot over the three mounting holes. You'll see that the pins don't seat completely into the holes. This means you need to take a bit more care in soldering than for the other components. You should be able to place the pot in the board and then turn the board over gently while keeping the pins in place. Then melt solder into the three holes from the back of the board. When finished, turn the board over and inspect the holes. If solder didn't flow all the way through, resolder. Also, try wiggling the pot to see if any of the legs are loose. If so, resolder. If necessary, you can solder from the front side of the board. When you're finished, the pot should be mounted firmly in place.

  2. Solder the other 4 pots onto the board. The board with all resistors and sockets is shown in Figure 12. By the way, if you're wondering why we don't use the yellow 1-k pot from the Multi-Trigger, that's because the 2.5-k pot has a greater sensitivity range. The sensitivity for the 2.5-k pot goes just as high as the 1-k pot; however, you can dial in lower sensitivities with the 2.5-k pot. This is something customers have asked for...a less sensitive sound trigger. Seriously. If you prefer to use the 1-k pot on the PCB, feel free.

via holes board with all resistors and sockets
Figure 11. 10-k variable resistor and mounting holes Figure 12. PC board with all resistors and sockets


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Soldering the Capacitors to the PCB


0.0047-uf capacitorThere 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 on the right, for example, has the number 473. From the Parts Guide, you can determine that this is a 0.0047-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 13. Seat them down to about the height of the pots. We realize that the photo is missing C8. We correct this oversight in a later photo.10-uf capacitor

  2. Turn the board over and solder the capacitor legs like you did the resistor legs. It may seem like you're not getting solder in the holes even when you are; turn the board over to inspect. Resolder if necessary. Wiggle the capacitor to make sure both legs are seated firmly. The legs are close together, so check carefully for solder bridges. Note the solder bridge in Figure 14. This was removed by drawing the tip of the soldering iron through the 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 to the right. 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 15. 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 16. Then turn the board over and solder the legs. Figure 17 shows the PC board with all components mounted so far.

  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.

mouting the ceramic capacitors Solder bridge between the legs of a capacitor location of C3 with polarity indicated electrolytic capacitors on PCB
Figure 13. Mounting the ceramic capacitors (C8 is temporarily missing) Figure 14. Solder bridge between the legs of a capacitor Figure 15. Polarity for C3 is indicated on the PCB Figure 16. Electrolytic capacitors seated on PCB (polarity indicated)
PCB with all capacitors mounted      
Figure 17. PCB with all capacitors mounted      


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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 18. 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 19. 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 20 and 21 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 18. Mounting the PN2222A transistor. Note the flat side. Figure 19. Using a heat sink on a transistor leg Figure 20. Inspecting for solder bridges Figure 21. Transistor soldered to PCB
SCR for photogate output (front view) SCR for photogate output (back view) Sound trigger output SCR Delay unit output SCRs
Figure 22: D1 SCR positioned on board Figure 23: D1 SCR seen from the back Figure 24: D2 SCR Figure 25: 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 22. Make sure the flat side faces toward the 8-pin socket. Note that the three legs are contained within the small square. The holes labeled A and C shown from the opposite side in Figure 23 are not used by the SCR. Go ahead and solder the legs of the SCR as you did for the transistor.

  2. Position SCR D2 for the sound trigger as shown in Figure 24 and solder into place.

  3. Position SCRs D3 and D4 for the instant and delayed outputs as shown in Figure 25 and solder into place.

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Soldering the LEDs to the PCB


The red LEDs are polar devices. The shorter leg is connected to the negative side of the circuit.

  1. Position LED1 as shown in Figure 26. Note that there is a flat side on the symbol on the PCB; this flat corresponds to the flat on the lip of the LED case. This is the negative side. Like the transistor and SCRs, you have to be careful not to heat up the LED too much while soldering. Either use a heat sink or solder quickly.

  2. Position LED3 similar to how you positioned LED1 and solder. The board with all components mounted so far is shown in Figure 27. If you're wondering about LED2, that's the infrared LED. It won't be mounted on the board. We'll get to that later.
Aligning the LED on the breadboard PCB with LEDs mounted
Figure 26. Aligning the LED on the breadboard Figure 27. PCB with LEDs mounted


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Soldering the Switches and Jacks to the PCB

  1. There are two SPDT switches. Slip them into the locations on the PCB labeled Input Selector and Delay Range. They can only be inserted one way. Solder the three pins of each switch on the back of the PCB. See Figure 28 for the mounted switches.

  2. There are four RCA jacks. Snap them into place as shown in Figure 29. Turn the board over. You need only solder the 8 holes indicated in Figure 30. These are the electrical contacts. If you want to solder the other holes to hold the jacks even more tightly, that's fine.

  3. Congratulations! You've now soldered all components to the breadboard as shown in Figure 31. What remains is to connect cables.

SPDT switches mounted on the PCB RCA jacks seated on PCB Soldering the RCA jacks PCB with all components mounted
Figure 28. SPDT switches mounted on the PCB Figure 29. RCA jacks seated on PCB Figure 30. Soldering the RCA jacks Figure 31. PCB with all components mounted


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Soldering the Cables to the PCB


  1. Insert the bare wires of the 9-V battery clip into the PCB as shown in Figure 32. Solder the wires to the PCB.

If you're using the optional Quick-Connect Cable Kit, skip to the page, Preparing Quick-Connect Cables. Otherwise, continue with step 2.


  1. Insert the bare wires of the piezoelectric disc into the PCB as shown in Figure 33. Solder the wires to the PCB.

  2. We assume that you've already prepared the photogate cables that are part of the Multi-Trigger Kit. We recommend using the cable with individual emitter and detector, because that cable is the more useful of the two photogate cables. The reason you need to make a choice is because you'll solder the cable to the PCB. If you prefer not to do this, here are two alternatives: i) Solder short lengths of hookup wire to the PCB in place of the three cable wires. Then use alligator clips to connect the photogate cable wires to the short lengths that you soldered to the PCB, ii) prepare quick-connect cables as described in Preparing Quick-Connect Cables.

For now, we'll assume that you're soldering the cable wires to the PCB. Refer to Figure 34 for the placement of the three wires. Even if the wires are already stripped, cut off the frayed ends and strip them again about 1/8 inch from the end. The reason for this is to make it easier to push the wires into the PCB holes. If, however, you still find it difficult to force all the strands through a hole, it's ok to snip off a few strands in order to be able to push the wire in. When you're finished soldering the connections, check with a magnifying glass to see if there are any free strands that are touching each other from neigboring wires. If so, snip the strands.

  1. If you haven't snipped all the component legs from the back of the board, do that now.

  2. Now you'll insert the ICs into the sockets. 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.

  3. Now for some embellishments. Refer to Figure 35. Stick-on labels have been added to the switches, and hook and loop tape has been used to provide strain relief for the photogate cable. The strain relief will help keep the cable connections from breaking off. To that end, hot glue has been used on the microphone and battery cable connections as well.

Connection of the 9-V battery clip to the PCB Connection of the piezo disc to the PCB Connection of the photogate cable to the PCB MT-PCB complete
Figure 32. Connection of the 9-V battery clip to the PCB Figure 33. Connection of the piezo disc to the PCB Figure 34. Connection of the photogate cable to the PCB Figure 35. MT-PCB complete


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Preparing the Trigger Cable

  1. In order to prepare a trigger cable to connect your Multi-Trigger PCB to a flash unit or camera, you need to start with a cable such as one of the four shown in Figures 36 - 39. 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 36 - 39 as you proceed with the instructions below.

In order to connect the cable to the RCA jacks on the PCB, you'll need to solder a male RCA connector 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 36. PC cable to connect flash to breadboard

Assembly instructions

Figure 37. Adapter to connect flash foot to breadboard

Assembly instructions

Figure 38. Cable to connect Camera Opto-Switch to breadboard

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

Figure 39. 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 36-39 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 40. 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 as shown in Figure 40.

  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 41 shows the completed solder joints. If you have a connectivity meter, use it to check for correct connectivity. The tip of the plug is electrically connected to the shorter lug, and the collar is electrically connected to the longer lug.

  4. Crimp the metal tabs around the gray cable and screw the jacket on. The completed connector is shown in Figure 42.

  5. A completed cable for connection from the PCB to a flash unit is shown in Figure 43. This completes assembly of the PCB, and it is now ready for testing.

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 40. Stripping wires in preparation to add RCA connector Figure 41. RCA plug connected to the red and black wires Figure 42. RCA plug connected to cable Figure 43. PC cable ready to connect to PCB


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Operating the PCB Multi-Trigger


For reference, the various functions are indicated on the photo below. Click for a larger image that will open in a different window.


Photogate with delayed flash


Photogate with delayed flash Sound trigger with flash on ST OUT Photogate with delayed camera Triggering a flash with the Opto-Switch
Figure 44. Photogate with delayed flash Figure 45. Sound trigger with flash on ST Out Figure 46. Photogate with delayed camera Figure 47. Triggering a flash with the Opto-Switch


Using the photogate with delayed flash (Figure 44)

  1. Lay the PCB out on a non-conducting, static-free (as much as possible) surface. The lid of a plastic project box will work or just a piece of cardboard or the pink antistatic bag that many of our kits are shipped in. The thing to avoid is any surface that will discharge to the PCB or that will create shorts between the metallic contacts on the back of the board. Now do the following:

    1. Set the input selector switch to PG.

    2. Set the delay range to 0.5 s.

    3. Turn the timeout knob about a quarter of the way clockwise from its minimum position.

    4. Turn the coarse delay (blue knob) all the way clockwise. The position of the fine delay (brown knob beside the blue knob) doesn't matter at this stage.

    5. Connect your flash to the delayed flash (FLA Del) output of the PCB using your trigger cable. Turn on your flash, preferably to low power.

    6. Connect a fresh 9-V battery to the battery clip.

    7. Align the LED and PT of the photogate cable and tape then down. (If you're using the interrupter cable, alignment is, of course, automatic.)

  1. The photogate alignment LED should be lit. If it isn't, try adjusting the white sensitivity pot one direction or the other. Setting the pot near the middle of its range should work. Note that if you change the separation of the infrared LED and PT, you may need to adjust the sensitivity to compensate. Try this if you want to see how you have to turn the pot to get the alignment LED to stay on.

  2. Run a finger between the infrared LED and PT. The alignment LED should go out momentarily. At the end of a short delay of about 1 second, the triggering indicator LED should light momentarily, and your flash should also discharge.

  3. Try the following adjustments to see how they affect the triggering indicator and the flash when you run your finger through the infrared beam.

    1. Turn the coarse delay down about half way. You should notice a reduction in the delay.

    2. Make a large change in the fine delay knob position. You probably won't notice a change in the delay. There actually is a change, but it would only be noticeable when photographing a high-speed event.

    3. Now turn the coarse delay up all the way and flip the delay range to 0.05s. This time you won't notice a delay. The switch divides all delay intervals by 10. You would use this setting when you need particularly small delays. For now, flip it back to the 0.5s position.

    4. Turn the timeout all the way up. This doesn't affect the delay, but it does increase the amount of time that the triggering LED is on. At maximum setting, this is about 1 second. This setting can be used to prevent multiple-exposures that would result from the flash unit going off more than once in quick succession.

Notes on operation:

  1. If you turn the timeout all the way to zero, the triggering indicator LED won't light but the delay unit will still provide an output.

  2. If you turn both coarse and fine delays all the way to zero, the unit won't trigger. Turn the fine delay up just enough to get triggering.

  3. Unclip the battery when you're not using the circuit. Otherwise, the photogate will drain the battery overnight.

Sound trigger with flash on ST Out (Figure 45)

  1. Set the following:

    1. Set the input selector switch to PG.

    2. Turn the red sensitivity knob all the way counterclockwise. This is the least sensitive position.

    3. Connect your flash to ST Out of the PCB.

    4. Connect your battery.

  1. Clap your hands or snap your fingers. The flash should discharge. This setup provides a nearly instantaneous discharge of the flash unit. The only significant delay is the time for sound to take to travel from the source of the sound to the piezoelectric disc. This setup is recommended for photographing balloon bursts, which happen very quickly. If you need to change the delay, you do so by moving the microphone different distances from the source of the sound. You can figure that there's a delay of about a millisecond (thousandth of a second) per foot (third of a meter) of distance.

  2. Now turn up the sensitivity until the flash discharges spontaneously. This typically happens after the half-way position. When you reach the position where the flash discharges spontaneously without sound, this means the circuit is so sensitive that it's always on. In this condition, the flash will no longer discharge. If you turn the knob just enough counterclockwise so that the flash will discharge with a snap of your fingers, then you're at the point of maximum sensitivity. We recommend that you not operate at this point if you don't need to. Keeping the knob turned about one-quarter of the way is a good operating position.

Note on operation: With the input selector on PG, you're bypassing the delay unit, which has no function when using ST Out. With the delay unit bypassed, the triggering indicator LED doesn't flash. While you could also have put the input selector on MIC, this isn't recommended if your flash unit has high voltage across its terminals. The latter can burn out the 556 timer when the flash is connected to ST Out and the input selector is set to MIC.


Sound trigger with delayed flash (no figure)


If you move the trigger cable to the FLA Del output and flip the input selector to MIC, then you can use the sound trigger with the delay unit. The delay unit functions the same as for the photogate described previously. Note, though, that the sensitivity will drift from the setting for ST OUT. If, say, you have the sensitivity set to its maximum as described above, then you'll find that the delay unit won't function with the sound trigger. But if you turn the sensitivity down, you can get the delay unit to function. That's why we recommend keeping the sensitivity at the one-quarter position. You won't have to worry about the drift in sensitivity when switching to the delay unit.


Photogate with delayed camera (Figure 46)

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


This setup is for triggering a camera shutter through an Opto-Switch. The difference between Figure 44 and Figure 46 is the output connection. The trigger cable is connected from the delayed camera (CAM Del) output to the TRIG jack on the Camera Opto-Switch. The camera shutter cable is connected from the CAM jack of the Opto-Switch to the camera. Both FOCUS and SHUTTER switches are on. With the input selector set to PG, running your finger through the photogate should actuate your camera shutter after whatever delay you've selected. Switch the input selector to MIC to use the sound trigger to actuate the camera.


Photogate with instant camera (no figure)


Move the trigger cable to the instant camera (CAM Inst) output in order to actuate the camera with no delay other than the inherent lag associated with the camera shutter. This setting is useful for photographing drops and splashes. The camera is connected to CAM Inst, and the flash is connected to FLA Del. The shutter speed is set to, say, 2. The photogate is set up a foot or less above the pool and the delay adjusted to capture the collision of the drop with the pool. When the drop passes through the photogate, the camera shutter opens and remains open for half a second. This is long enough for the drop to reach the pool and the flash to discharge. The shutter then closes automatically.


Specialized setup: Triggering a flash with the Opto-Switch (Figure 47)


RCA to 3.5mm adapterYou can trigger a flash unit with the Opto-Switch as long as the flash unit doesn't have high-voltage terminals. In this case, high voltage means greater than 75 V. The trigger cable is connected from either of the CAM outputs on the PCB to the TRIG jack on the Opto-Switch. The CAM jack on the Opto-Switch is connected to the flash unit. An adapter may be required to convert RCA male on the flash trigger cable to 3.5mm male on the Opto-Switch. The adapter shown in the photo on the right will work. In operation, the SHUTTER switch is turned on; the FOCUS switch may be on or off.


One possible application is to double your flash output. Connect one flash to the CAM Del output using the Opto-Switch and another flash to the FLA Del output. The two units should discharge essentially simultaneously.


Triggering a flash with wireless devices External input of PCB Flash output holes
Figure 48. Triggering a flash with wireless devices Figure 49. Sound trigger with flash on ST OUT Figure 50. Flash outputs on the PCB  


Specialized setup: Triggering a flash with wireless devices (Figure 48)

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


You can connect a wireless transmitter to either ST Out or DEL Fla and trigger a flash unit connected to a wireless receiver. The setup is shown in Figure 48. Note that an adapter may be required to connect the trigger cable from the delayed output to the transmitter. The type of adapter will depend on the jack on the transmitter. For the PocketWizard Plus II unit shown, an adapter like the one shown previously will work. Be aware that the use of a wireless transceivers introduces an additional delay of 1-2 milliseconds whether using an instant or delayed output.


Using the External Input


You can connect other triggers to the delay unit using the external input. The output of the trigger must be a simple circuit closure in order for this to work. A contact trigger is a useful external trigger. Make connections to the PCB at the holes labeled Delay Input and Gnd (see Figure 49). When using an external input, the input selector must be set to MIC.


Connecting Other Flash Outputs


You can connect a trigger cable by soldering directly to the board if you wish. See Figure 50. Near each SCR is a pair of holes labeled A and C. Solder the positive wire of the trigger cable to A and the negative wire to C. Note that these outputs are for flash rather than camera.




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