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What you need
These instructions show how to prepare and use the PC board for the Multi-Trigger Kit, MT-PCB2. This kit comes complete with all the parts needed for assembly of a working Multi-Trigger on a PC board. 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.
15-30 W soldering iron (with a new or pointed tip) and solder
Wire stripper (photo below)
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.
Needle-nose pliers (photo below) make it easier to handle small components, especially if you have big fingers.
A heat sink (photos below) protects heat-sensitive components while soldering.
A desoldering tool (photos below) helps in clearing solder from a hole. The cylindrical type works better than the bulb.
A magnifying glass is used to inspect solder joints.
A lighter or matches to shrink heat-shrink tubing
Hot glue gun
Wire cutters and
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.
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
If 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.
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.
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.
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.
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.
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.
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
Go ahead now and solder the remaining fixed-value resistors onto the board. There are 14 of them. 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.
Figure 5. Via holes (circled in yellow) and solder holes
Figure 6. PC board with all fixed-value resistors mounted
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.
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.
Place the 8 pins of the socket into the corresponding holes on the PCB as shown in Figure 8.
Turn the board over and bend the pins down to the side to hold the socket in place as shown in Figure 9.
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.
Solder the 14-pin socket to the board similar to how you did the 8-pin socket.
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. Seat the legs of the pot into the holes. Then melt solder into the three holes from the back of the board. When you're finished, the pot should be mounted firmly in place.
Solder the other 4 pots onto the board. The board with all resistors and sockets is shown in Figure 12.
Figure 11. 10-k variable resistor and mounting holes
Figure 12. PC board with all resistors and sockets
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 ceramic capacitor on the left in Figure 13, for example, has the number 473. From the Parts Guide, you can determine that this is a 0.047-μf capacitor.
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. Bend the legs over on the back.
Turn the board over and solder the capacitor legs like you did the resistor legs.
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 electrolytic 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 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.
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.
Figure 13. Ceramic (left) and electrolytic (right) capacitors
Figure 14. Mounting the ceramic capacitors
Figure 15. Polarity for C3 is indicated on the PCB
Figure 16. Electrolytic capacitors seated on PCB (polarity indicated)
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.
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.
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.
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
Figure 22: D1 SCR positioned on board
Figure 23: D2 SCR for ST Out
Figure 24: D3 and D4 SCRs for instant and delayed outputs
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. The flat side also coincides with the symbol printed on the board. Solder the legs of the SCR as you did for the transistor.
Position SCR D2 for the sound trigger as shown in Figure 23 and solder into place.
Position SCRs D3 and D4 for the instant and delayed outputs as shown in Figure 24 and solder into place.
The red LEDs are polar devices. The shorter leg is connected to the negative side of the circuit.
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.
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, which isn't mounted on the board.
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.
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.
Congratulations! You've now soldered all components to the breadboard. What remains is to prepare and connect 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
The 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 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.
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
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 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.
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.
The 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
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
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.
Soldering the Cables to the PCB
Insert the bare wires of the 9-V battery clip into the PCB as shown in Figure 32. Solder the wires to the PCB.
Insert the bare wires of the piezoelectric disc into the PCB as shown in Figure 33. Solder the wires to the PCB.
Now you're ready to connect the SPG1 photogate cable to the PCB. If you plan to switch this cable out with the SPG2 cable at a later date, you may want to consider a quick-connect method. Use short pieces of single-strand hookup wire for this purpose. You can solder these wires to the PC board in the holes where the photogate cable would beconnected. Then you can use alligator clips to connect the photogate cable wires to the short lengths that you soldered to the PCB. (Another possibility is to prepare quick-connect cables as described in Preparing Quick-Connect Cables.)
Refer to Figure 34 for the placement of the three wires. In the event that you're soldering the cable wires directly to the PCB and you find it difficult to force the wires through the holes, 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.
If you haven't snipped all the component legs from the back of the board, do that now.
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.
Add the stick-on labels to the switches as shown in Figure 35.
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
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.
Figure 36. PC cable to connect flash to breadboard
Unscrew the black jacket from the RCA plug as shown to the right.
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.
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.
Crimp the metal tabs around the
gray cable and screw the jacket on. The completed
connector is shown in Figure 42.
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.
Figure 40. Stripping wires in preparation to add RCA connector
Figure 41. RCA plug connected to the red and black wires
For reference, the various functions are indicated on the photo below. Click for a larger image that will open in a different window.
The PCB board shown in Figures 44-48 is a revision earlier than the current revision 4. The photogate, instant output, and external input cables are shown connected at different locations to the board. However, all functions remain unchanged.
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
Figure 48. Triggering a flash with wireless devices
Using the photogate with delayed flash (Figure 44)
Lay the PCB out on a non-conducting, static-free (as much as possible) surface. The pink antistatic bag that the kit is shipped in will work. 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:
Set the input selector switch to PG.
Set the delay range to 0.5 s.
Turn the timeout knob about a quarter of the way clockwise from its minimum position.
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.
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.
Connect a fresh 9-V battery to the battery clip.
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.)
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.
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.
Try the following adjustments to see how they affect the triggering indicator and the flash when you run your finger through the infrared beam.
Turn the coarse delay down about half way. You should notice a reduction in the delay.
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.
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.
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:
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.
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)
Set the following:
Set the input selector switch to PG.
Turn the red sensitivity knob all the way counterclockwise. This is the least sensitive position.
Connect your flash to ST Out of the PCB.
Connect your battery.
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.
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)
You 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.
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.
Figure 49. Connection points for external input
Figure 50. Flash outputs on the PCB
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 Ext Input and Gnd (see Figure 49). When using an external input, the input selector must be set to MIC.
You can also connect a pushbutton to the external input to serve as a test button.
Connecting Other Flash Outputs
You can connect a trigger cable by soldering directly to the board if you wish. See Figure 50. The output on the left is for triggering a flash directly from the photogate, bypassing the delay unit. This output should only be used with low-voltage flash units.
The output on the right is for triggering a flash from the instant output of the delay unit. High-voltage flash units can be used with this output.