information and inspiration
for students, teachers and hobbyists
About Tools Products Activities Galleries Projects Links Contact Facebook LinkedIn  flickr


Assembly and Operating Instructions for Kits


Assembly Instructions for the AstroSplash Drop Controller


Assembly instructions for other kits




Building the control box

What you need

Parts guide and schematic

Soldering the resistors and diodes to the PCB

Soldering the IC sockets to the PCB

Soldering the capacitors to the PCB

Soldering the MOSFET driver and the fuse holder to the PCB

Drilling holes in the project box lid

Adding the label for the lid

Adding the components to the lid

Wiring the box lid

Connecting the PCB to the lid

Finishing the board and the box

Assembling the trigger cable

Valve kit assembly (opens in a new tab)


Operating instructions (opens in a new tab)

Guide to Setting Up Your Drip Photography System (opens in a new tab)


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 AstroSplashThese instructions show how to prepare and use the PC board and project box enclosure for the AstroSplash Drop Controller. The ADC comes complete with all the parts needed for assembly of a working unit on a PC board enclosed in a project box. Also included are parts for a trigger cable.


The PC board is shown to the right. You'll see that the locations for the components are labeled with symbols like R6, 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

  • 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 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
    Wire cutters and stripper Small diagonal cutter Needle-nose pliers Desoldering tools



    diagonal cutter


    needle-nose pliers

    desoldering tool desoldering bulb


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 components

  • Drill motor and bits to drill holes in the project box lid. Bit sizes are 3/32", 1/8", 1/4", 5/16", and 3/8". (For metric equivalents in millimeters, multiply by 25.) You can substitute a 1/8" bit for the 3/32" one.
  • Hammer, punch (or nail), small round file
  • Wrenches or sockets to tighten components onto the project box

For the label

  • Scissors or stencil knife and straightedge to cut out the label
  • Stencil knife or razor blade to cut out the holes
  • 1/4" hole punch (not required but helpful)
  • Masking or blue tape
  • Glue such as contact cement or spray adhesive. (Elmer's Rubber Cement, shown below, works well.)

desoldering bulb


For the knobs

  • A jeweler's screwdriver to tighten the set screws (in a pinch, the tip of a knife blade will do)

Aids to troubleshooting


If you need to troubleshoot problems with the circuit, it will help to have at least some basic skills in building and testing electrical circuits. These involve such things as testing for polarity and continuity, for examining solder connections, and for measuring voltages. In addition to such knowledge and exerience, having a continuity checker or multimeter and clip wires may be helpful.


Parts guide and schematic


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. You may also find it helpful to print this pdf document for reference while you work. A schematic circuit diagram is included.


Before starting work in each section, we recommend reading through the section completely in order to get an overview of what you'll be doing.


Soldering the resistors and diodes to the PCB


1-megohm 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. We'll start with R1, a 1-megohm resistor that will be soldered to the PCB. 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 here, the bands are brown-black-green.

  1. Insert the legs of resistor R1 over the rectangular space labeled R1 on the PCB. See Figure 1. 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. 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. Snip off the legs of the resistor. The completed solder joints are shown in Figure 3 from the underside. They're circled in yellow. 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. 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 4, 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.

Open the Parts Guide in a separate tab so that you can see which resistors go with which numbers for what follows.

  1. Solder resistors R2 - R17 and R20 - R23 onto the board. Note that R18 and R19 are omitted. You'll solder them to the lid later. Note also that R15 may or may not be labeled on the board, depending on what production run you have. However, it's the only 100-ohm resistor. It's shown in Figure 5.

  2. Figure 6 shows all the resistors soldered to the board. R15 is also highlighted here.

  3. 1-megohm resistorThere are 4 diodes to solder to the board. See the photo of a diode to the right. Unlike resistors, diodes only allow current to pass in one direction. The gray band on one end is used to orient the diode correctly. See Figure 7 for how the gray band aligns with the corresponding band for D1 on the PCB.
  4. Read the side of a diode to determine whether it's a 1N4001 or a 1N4004. There are 3 of the former and 2 of the latter. One of the 1N4004 diodes will be soldered to the lid, so you can set that one aside for now. Solder the three 1N4001 diodes into the holes for D1, D2, and D3. Solder one of the 1N4004 diodes into the holes for D4. Figure 8 shows all the diodes soldered in place.
inserting R1 legs of R1 completed solder joints for R1 via holes
Figure 1. Resistor R1 inserted into dedicated space on PCB Figure 2. Legs of resistor R1 protruding from back of PCB Figure 3. Completed solder joints, circled in yellow, from the underside of the PCB Figure 4. Via holes (circled in yellow)
R15 on the board all resistors mounted diode alignment diodes soldered to the board
Figure 5. R15 is the 100 resistor Figure 6. PC board with fixed-value resistors mounted. Note the position of R15. Figure 7. Alignment of diode on PCB Figure 8. Diodes D1-D4 soldered to the board


Back to top


Soldering the IC sockets to the PCB


The three 14-pin and one 16-pin IC socket will be used to seat the four ICs. The latter won't be added to the sockets until later.

  1. See Figure 9, which shows one of the 14-pin sockets seated in the board in the U1 location. Note that the socket has a notch on one end. Line this notch up with the one on the PCB when you seat the socket into the board. Make sure all the legs are seated in the corresponding holes.

  2. Turn the board over and bend the pins down on either side to hold the socket in place as shown in Figure 10.

  3. Solder the 14 pins to the board. The finished result is shown in Figure 11. 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 pins.

  4. Now solder the other two 14-pin sockets into U2 and U3 and the 16-pin socket in U4. Remember to line up the notches. Figure 12 shows the board with all sockets soldered into place.

Socket seated in position U1 Pins crimped over on back of PCB Pins crimped over on back of PCB all sockets soldered onto board
Figure 9. 14-pin socket seated in position U1 Figure 10. Pins crimped over on back of PCB Figure 11. All 14 pins soldered to the board Figure 12. All sockets, resistors, and diodes soldered to PCB


Back to top


Soldering the capacitors to the PCB


There are two kinds of capacitors, ceramic and electrolytic. There are 19 of the ceramic capacitors; they all have a disc shape and are orange or yellow in color. A number on the disc identifies the capacitor. See Figure 13 for how to associate the number with the value of the capacitance. (Note that the numbers 472, 473, and 104 may be followed by an M, and there may be other markings on the capacitor as well.)


  1. Refer to Parts Guide or component list to see which capacitors are associated with C1, C2, etc. on the PCB. C1 is a 0.0047-μf capacitor. Figure 14 shows the capacitor legs inserted into the holes on the PCB. 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. The legs should extend about 1/8" from the top side of the board. Bend the legs over on the back to keep the capacitor from slipping out when you turn the board over. Then solder the legs on the back.

  2. Next you'll solder an electrolytic capacitor. There are 2 of these, C17 and BC1, and both are 4.7μf . The electrolytical capacitors have cylindrical metal cases with the value of the capacitance printed on them. 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. See the photo of two sides of a 4.7-μf capacitor in Figure 15. The shorter leg is negative and corresponds with the light-colored strip on the case. Now look at Figure 16 for the location of capacitor BC1 in the upper left-hand corner of the board. Note the small + sign on the left side of BC1. This indicates that the positive leg of the capacitor goes in the left hole. Figure 17 shows a view from a different angle, indicating the placement of the capacitor. Solder the capacitor now.

  3. Solder the remaining 19 capacitors (C2-17, BC2-4) on the board and clip the protruding legs. Note that the label for C4 is obscured by a via hole. See Figure 18a. Make sure you mount capacitor C4 between C3 and C5. The board with all capacitors mounted is shown in Figure 18b.

0.0047-uf capacitor 472 = 0.0047 μf

0.0047-uf capacitor473 = 0.047 μf

0.0047-uf capacitor104 = 0.1 μf

C1 on the PCB 4.7-uf capacitor BC1 on the PCB
Figure 13. 0.0047-μf ceramic capacitor Figure 14. C1 capacitor in the PCB Figure 15. Two views of a 4.7-μf electrolytic capacitor Figure 16. Location of BC1 showing + side
Placement of BC1 capacitor on the PCB Position of C4 on the PCB PCB with all capacitors in place  
Figure 17. Placement of BC1 capacitor on the PCB Figure 18a. Position of C4 on the PCB Figure 18b. PCB with all capacitors in place  


Back to top


Soldering the MOSFET driver and the fuse holder to the PCB

  1. There are just two components left to solder to the PCB. The placement of the MOSFET driver is shown circled in yellow in Figure 19. Note the orientation with the gray side in front. Figure 20 shows the component from the reverse side. Seat the legs as far as you can and solder them to the underside of the board. The legs are close together so be careful about solder bridges.

  2. The last component for the board is the fuse holder. It'll take a bit of force to snap the 2 legs into place. Once in place, solder the legs. Figure 21 shows the board with all components in place with the exception of the ICs and fuse, which will be added as the final step.

Placement of the MOSFET driver MOSFET driver from the back MOSFET driver from the back
Figure 19. Placement of the MOSFET driver Figure 20. MOSFEt driver from the back Figure 21. PCB with all components excepts ICs and fuse  


Back to top


Drilling holes in the project box lid


You can set the PCB aside for now. You'll prepare the lid next.

  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) between the 4 mounting holes. This is important, because the hole pattern is the mirror image of the top of lid. Position the template inside the lid as shown in Figure 22. You might want to tape it down to keep the position from shifting. 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". See Figure 23 showing all the pilot holes. Note that this is top (outer) view of the lid.

  3. For drilling the larger holes, we recommend spade bits, as these produce cleaner holes and have less tendency to grab the plastic than a spiral bit. The hole size is most critical for the LED holders. If the hole is slightly small, it will take a lot of force to snap the LEDs into the holder. If the hole is slightly large, the LED will wobble in holder; however, this won't affect its function. See Figure 24 with all the holes drilled to size. Again this is a top (outer) view.

Placement of the inner template Lid with pilot holes drilled Holes drilled to size in lid  
Figure 22. Template placed in underside of project box lid Figure 23. 3/32" pilot holes drilled in the box lid (top view) Figure 24. Holes drilled to size (top view)



Back to top


Adding the label for the lid

  1. Figure 25 shows the lid label. You'll need to trim the edges to the black border, but before trimming, see Figure 26, which shows the label as it will be placed on the top of the lid. Note how the label is trimmed so that the corners don't interfere with the mounting holes. We recommend using a stencil knife with a rule or straightedge in order to get clean lines when you trim. However, a pair of sharp scissors will work, too.
  2. Next you'll laminate the label. This will help protect it from marks and scratches. Two laminating sheets are provided. Remove the paper back from one of the sheets and gently press the label face down onto the sticky side of the laminate film. See Figure 27.
  3. Turn the label over. Remove the paper backing from the other sheet of laminate and stick the back side of the label down onto the laminate. Smooth out any air bubbles. Then trim the laminate away around the borders of the label, leaving about 1/16" of the laminate protruding around the edges of the label. This allows to the two sheets of film to hold together on the edges. See Figure 28 for the completed lamination.

Carry out this alignment procedure before you glue the label to the lid

  1. In order to help in aligning the label with the holes drilled in the lid, punch or cut some alignment holes. A 1/4" hole punch works well for this. You can punch out all the 1/4" holes around the periphery of the label. See Figure 29. If you don't have a punch, you could use a stencil knife or razor blade. Don't worry if the edges of the holes are a bit ragged. This will be covered when you mount the components later.

  2. Now place the label on the lid with the 1/4" holes of the label aligned with those drilled on the lid. See Figure 30 for a top view. You can use the 1/4" wooden dowels provided in the kit to help align the label with the holes in the lid. See Figure 31 for a view of the underside of the aligned label. (We've started supplying 1/4" OD plastic tubing instead of wooden dowels. The tubing can be cut into 1" sections.)

  3. Once you have the label aligned, use blue tape or masking tape to prevent glue from reaching areas where you don't want it. Figure 32 shows the masked area after the label has been removed for gluing.

  4. On the label itself, mask the holes that you previously cut or punched. This will prevent glue from bleeding onto the label. See Figure 33.

  1. Now you're ready to glue. Spray or spread it uniformly on the lid and the back of the label. Depending on the adhesive that you use, you may have to wait several minutes before pressing the label onto the lid. When you do, make sure the holes align. Remove the tape right away to prevent the glue from gluing the edges in place.
  2. You can now cut out the rest of the holes. We recommend using a small stencil knife as shown in Figure 34. Don't use a drill bit for this, as that will rough up the edges of the holes too much.
  3. The completed label glued to the lid with all holes cut out is shown in Figure 35.
Lid label Label placed on the lid Placing the label face down on the laminate Lamination of the label complete
Figure 25. Label for the lid Figure 26. Label placed on the lid Figure 27. Placing the label face down on the laminate

Figure 28. Lamination complete

Punching the 1/4" holes for alignment 1/4" holes of label aligned with those on lid Interior of lid showing alignment holes circled in yellow Masking the top of the lid
Figure 29. Punching the 1/4" holes for alignment Figure 30. 1/4" holes of label aligned with those on lid Figure 31. Interior of lid showing alignment holes circled in yellow Figure 32. Masking the top of the lid
Masking the holes to prevent bleeding of the glue Figure 34. Cutting out a hole with a stencil knife The completed label will all holes cut out  
Figure 33. Masking the holes to prevent bleeding of the glue Figure 34. Cutting out a hole with a stencil knife Figure 35. The completed label will all holes cut out  


Back to top


Adding the components to the lid

  1. We'll start with the push button for the CLEAR function. See Figure 36 for placement. The screw base is actually a bit more than 1/4", so you may need to file the hole slightly or scrape it with a pocket knife in order to insert the push button. This is the only component that is oversized. Put on the lock washer and nut and tighten it down.

  2. We'll do switches next. See Figure 37 for a switch with the washers, nuts, and rings removed. The guide ring to the lower right in the photo has a tab that is used to keep the switch from twisting. Typically, this is placed on the top of the lid; however, we're putting it on the bottom. That's to avoid having the guide holes show on the label. See Figure 38 for how the ring for the power switch is positioned. Figure 39 shows a close up.
  3. Figure 40 shows a closeup of the switch in place. Bolt it in place using the washer and one nut on the top of the lid. The second nut won't be used.
  4. Mount the other two switches. See Figure 41 for all switches in place, as seen from the underside of the lid. Figure 42 shows the view from the top of the lid.

  5. Mounting the 3.5-mm jacks is easier than the switches. The cream-colored jacks* are mono, and the black one is stereo. Simply remove the nut, insert the jack, put the nut back on and tighten. Figure 43 shows all the 3.5-mm jacks in place. Note that the upper and lower jacks are circled in yellow. We found after our initial assembly that it would be better if the lugs on the side were all turned to face in the same direction to the right, the same as the two jacks in the middle. This keeps the lugs for the outer jacks from being too close to the standoffs when they're put in place later. Therefore, we recommend turning the side lugs on the upper and lower jacks to point to the right.
  6. Next is the BNC jack. Simply slip it into the hole and bolt in place. Note the orientation of the side lug shown in Figure 44.
  7. Install the 4 DC power jacks next. See Figure 45 for the locations below the BNC jack. The power jacks have 3 lugs; we numbered these for convenience in Figure 45. Note the orientation of the center lugs, labeled 2.
  8. The 4 LED holders are next. Each holder has two parts, a collar and a ring, shown in Figure 46. The collars are pushed into the LED holes first. The notched side protrudes from the underside of the lid as shown in Figure 47 for the power LED next to the power switch. The LED collar is circled in yellow.

*For a while, our supplier was providing mono jacks in a gray color, but these work the same as the cream-colored jacks.

Continue below the photos.

Pushbutton mounted on the lid Switch with various parts removed Guide ring positioned for the power switch Close up of the guide ring positioning
Figure 36. Push button mounted on the lid Figure 37. Switch with various parts removed Figure 38. Guide ring positioned for the power switch Figure 39. Close up of the guide ring positioning
BNC jack mounted All switches mounted All switches mounted, top view 3.5-mm jacks mounted
Figure 40. Close up of the switch in place from the underside of the lid Figure 41. All switches mounted, underside Figure 42. All switches mounted, top view Figure 43. 3.5-mm jacks mounted
3.5-mm jacks mounted DC power jacks mounted Parts of an LED mount LED collar in place next to the power switch
Figure 44. BNC jack mounted Figure 45. DC power jacks mounted Figure 46. Parts of an LED mount Figure 47. LED collar in place next to the power switch
Power LED mounted in place The 4 LEDs are in place All pots mounted Lid of the box with all components (except for standoffs) mounted
Figure 48. Power LED mounted in place Figure 49. The 4 LEDs are in place Figure 50. All pots mounted Figure 51. Lid of the box with all components (except for standoffs) mounted
  1. Push the LEDs into the collars from the underside of the box. Orient LED1 (the power LED) with the longer leg toward the outside of the lid. Orient LEDs 2-4 (the pulse LEDs) with the longer leg toward the inside of the lid. When you insert an LED, it's important to get it to snap into the collar. It may take quite a bit of extra force to push it in 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. Once the LEDs are snapped into place, slip the rings over the protruding notched part as shown in Figure 48 and seat them firmly against the lid surface. Figure 49 shows all 4 LEDs in place.

  2. The remaining 5/16" holes are for the five 1-M potentiometers. Note that each of the pots has a tab which is inserted into the corresponding guide hole. We recommend snipping off about one-third the length of the tabs. This prevents the tabs from pushing up against the label on the lid. When you remove the nut, you'll find two washers. You can put one below the lid and one above. When you tighten down the nut, don't overtighten as that could impede the operation of the pot. Figure 50 shows all components mounted on the lid, with the exception of the standoffs which will be added later. Figure 51 shows the top of the lid. The knobs may be added in the final stages of assembly.

Back to top


Wiring the box lid


Two resistors and one diode will be wired directly on the box lid. We'll lead you through those connections first. Make connections for now but don't do any soldering yet.

  1. The remaining two 1-kΩ resistors are each wired from a switch to the longer leg of an LED. (The resistors are R18 and R19 in the Parts List.) Figure 52 shows how the resistors are wired. You'll need to clip the legs of the resistors to make them fit. Something to help in spiraling the resistor legs around the LED leg is to wrap the resistor leg around a small nail first as shown in Figure 53.

  2. Close ups of the connections are shown in Figures 54 and 55. Note that the connection is to the longer leg of the LED, which will be the inner leg if you oriented the LEDs as recommended earlier.

  3. The remaining 1N4004 diode is connected across the positive and negative terminals of the Valve1 jack. See Figure 56 for the location of that jack. A close up of the connection of the diode is shown in Figure 57. Note that the gray band is positioned toward lug 3.You'll need to trim the legs to avoid having a lot of excess wire.

Continue below the photos.

1-kΩ resistors each connected between a switch and an LED Wrapping a resistor leg around a nail Closeup of resistor connections View of resistor connections from the side
Figure 52. 1-kΩ resistors each connected between a switch and an LED Figure 53. Wrapping a resistor leg around a nail Figure 54. Closeup of resistor connections Figure 55. View of resistor connections from the side
Diode connected to Valve1 jack Diode connected to between pins 2 and 3 (gray band toward 3) White wires added between components White wires added between components
Figure 56. Diode connected to Valve1 jack Figure 57. Diode connected between pins 2 and 3 (gray band toward 3) Figure 58. White wires added Figure 59. Red wires added
Black multistrand wires added between components Red multistrand wires added between components Connections to solder circled in yellow Soldering completed
Figure 60. Black multi-strand wires added Figure 61. Red multi-strand wires added Figure 62. Connections to solder circled in yellow Figure 63. Soldering completed


  1. Now you're ready to add wires. Start with the single-strand, white wire. See Figure 58 for the connections. Cut each wire to span the distance between the components with an extra 1/4" on ends that will be looped through lug holes and an extra 1/2" on ends that will be wrapped around LED legs. Strip back those ends with your wire stripper. Specifically, here are the connections:
Side lug of TEST jack --> Shorter leg of LED4 --> Shorter leg of LED3 --> Shorter leg of LED2 --> Side lug of TRIG jack
(lug 1 in photo to the right)
Solder lugs of 3.5mm monoo jack (inverted)
  1. The single-strand, red wires are next. See Figure 59 for the connections. They're described in the table below.
Lug 1 of Pe --> Lug 1 of Pc --> Lug 1 of Pa --> Lug 1 of Pd --> Lug1 of Pb solder lugs of potsolder lugs of pot (inverted)
--> Longer leg of LED1
  1. You'll connect multi-strand wires next. Cut a 2-ft section from the 2-conductor gray cable shown below. Strip off the gray insulation, leaving the red and black multi-strand wires. Set the red wire aside. You'll use it in step 7. The connections for the black wires are given below and shown in Figure 60. The black wires are difficult to see against the black box, so we've specified the connection points with letters.
Solder lugs of 3.5mm monoo jack (inverted) (a) Lug 2 of VALVE3 --> (b) Lug 2 of VALVE2 --> (c) Lug 2 of VALVE1 Solder lugs of the DC jack and (d) Lug 2 of +12V IN (2) Left side of CLEAR
--> (f) Right side of CLEAR
  1. To complete the connections between components on the lid, you'll use the red multi-strand wire. See Figure 61 and the table below.
Lug 3 of VALVE3 --> Lug 3 of VALVE2 --> Lug 3 of VALVE1 and Lug 3 of +12V IN Outer lug of SW1
  1. You can solder some of the connections now in order to stabilize them so that the wires don't slip out when you connect the wires that jump to the PCB. We provide some tips on soldering below. Only solder those connections that will not have jumper wires. See Figure 62 for the connections that can be soldered now. These are circled in yellow. The completed soldering is shown in Figure 63.

Using a heat sinkSoldering to the legs of the LEDs: Before soldering, push the wrapped wires to be soldered down close to the red case of the LED. This will allow you to trim the legs of the LED to prevent them from coming in contact with other components and creating shorts. See the close up of some LED solder connections to the right.


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 DC power jacks: Be very careful not to get so much solder on the lugs 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.


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.


Back to top


Connecting the PCB to the lid


The last phase of assembling the box is to connect jumper wires between components on the lid and the PCB. Print this pdf document to serve as a handy reference as you work.


  1. Begin by cutting the lengths of the wires that you'll need. Here's a table with colors, type (S = single strand or M = multi-strand), and length in inches. For conversion to centimeters, multiply by 2.5. The PCB ID refers to the symbol on the PCB. The order of symbols in the table is clockwise around the perimeter of the PCB. Note that two holes on the PCB will not be connected. These are shown in Figure 64.
PCB ID Color Type Length   PCB ID Color Type Length
PJ- black M 4.0 AUX1+ green S 3.5
TRIG green S 5.5 AUX1- blue S 5.0
Pa2 yellow S 3.5 AUX2+ green S 4.5
Pb2 yellow S 5.0 AUX2- blue S 5.5
Pc2 yellow S 2.5 LED1 white S 2.5
SW2i green S 1.5 LED2 red S 5.0
Pd2 yellow S 4.5 TEST red M 5.0
GND white S 3.0 VLV- black M 4.0
Pe2 yellow S 5.0 RET black M 2.0
SW3i green S 5.0 SW3o blue S 3.5
P1 red S 2.0 SW2o blue S 4.0
CAM S yellow S 3.5 SW1 red M 2.5
CAM C white S 3.5 VLV+ red M 2.0
CAM F green S 3.0        
Holes circled in yellow will not have connections

Jumper wires connected to the lid

PCB in position First 5 jumpers connected to the board

Figure 64. Holes circled in yellow will not have connections

Figure 65. Jumper wires connected to the lid

Figure 66. PCB in position

Figure 67. First 5 jumpers connected to the board


  1. The connections to make from the lid to the PCB are given below. Don't concern yourself with the PCB yet. Connect the jumper wires to the lid first. Figure 65 shows the lid with all jumper wires connected and soldered in place. Notice that the 4 standoffs have been added to the lid. For the TRIG and CAM jacks, note how close lug 1 is to a standoff. This is why we recommended earlier that you turn the jacks so lug 1 points to the right. In the event that you didn't turn the jacks, another option is to wrap some electrical tape around the standoffs to provide insulation.

You may find it useful to print Figure 65 for reference while you work. Since it may be difficult to see which lugs of some of the jacks to connect to, see the photos below for our numbering scheme for the lugs. The connection that may be the most difficult to make is to lug 2 of the +12V IN jack. There are three black, multi-strand wires going to that lug. It can be done, but it takes some patience to get all the strands through the hole. For the TEST jack, just slip the wire into the center sleeve. You'll need to hold it in place while you solder.


PCB ID LID   PCB ID LID Lug numbering
PJ- Lug 2 of +12V IN AUX1+ Lug 3 of AUX1
Solder lugs of the DC jack

solder lugs of pot

solder lugs of pot (inverted)

Solder lugs of 3.5mm monoo jack (inverted)
Solder lugs of the 3.5mm stereo jack
TRIG Lug 3 of TRIG AUX1- Lug 1 of AUX1
Pa2 Lug 2 of Pa AUX2+ Lug 3 of AUX2
Pb2 Lug 2 of Pb AUX2- Lug 1 of AUX2
Pc2 Lug 2 of Pc LED1 Shorter leg of LED1
SW2i Center lug of SW2 LED2 Longer leg of LED2
Pd2 Lug 2 of Pd TEST Center terminal of TEST
GND Lug 1 of TRIG* VLV- Lug 2 of VALVE3
Pe2 Lug 2 of Pe RET Lug 2 of +12V IN
SW3i Center lug of SW3 SW3o Left lug of SW3
P1 Lug 1 of Pb SW2o Left lug of SW2
CAM S Lug 3 of CAM SW1 Center lug of SW1
CAM C Lug 1 of CAM VLV+ Lug 3 of VALVE3
CAM F Lug 2 of CAM    


*Note that the GND wire connects to the side lug 1 together with the previously connected white wire. There is no connection to lug 2 of the jack.

  1. This brings us to the final assembly stage of the box, connecting the jumper wires to the PCB. Stick-on labels are included in the kit for labeling the wires to help keep track of them. See Figure 66 for how the PCB is positioned on the lid. Don't bolt it down yet, because you need to be able to move the board around as you make connections. We recommend making the connections in 4 rounds. For the 1st round, connect these jumpers: SW1, LED1, TEST, GND, SW2i. Most of these are short wires. Once you've soldered them in place, the board will stand above the lid on its own. See Figure 67 for the 5 connection points on the PCB. They're circled in yellow.
  2. For the 2nd round of soldering, do the following wires: Pb2, Pd2, SW2o, SW3o, Pe2, SW3i, LED2, TRIG, Pa2, Pc2, P1 (same as Pb1, though marked P1 on the PCB). You'll have to thread some of them under the PCB.
  3. For the 3rd round, do the remaining multi-strand wires: VLV-, RET, PJ-, VLV+.
  4. For the final round, do the outputs: CAM S/F/C, AUX1+/-, AUX2+/-. These are all in a row along the bottom of the PCB. See Figure 68 below.
  5. If you haven't clipped the legs of the LEDs, do that now.
Output holes circled in yellow

Seating the ICS and the fuse

The completed assembly The completed box

Figure 68. Output holes circled in yellow

Figure 69. Seating the ICS and the fuse

Figure 70. The completed interior assembly

Figure 71. The completed box


Back to top


Finishing the board and the box

  1. Gently push down on the PCB to compress the wires below it. Then bolt the board in place on the standoffs.
  2. Add the ICs next. When you insert an IC into socket, make sure all the pins are aligned before you start pushing down. Otherwise you may crimp a pin and break it off. Align the three 556 chips by the notch as indicated in Figure 69 above. For the P2501-4, there's a small light-colored dot on one end. Position this as shown in the photo.
  3. Insert the fuse in the clips. You'll have to apply some force to snap the fuse into the clips. Figure 70 above shows a side view of the completed assembly.
  4. Place the lid over the bottom of the box, being careful not to pinch any wires between the lid and the base. You can screw in the 4 corners now or wait until later after you've completed testing.
  5. Turn the shafts of all the pots all the way counterclockwise. When you seat a knob on a shaft, orient the white marker with 8 on the time scale. Then tighten the set screw. (If you find that it's difficult to push a knob onto a shaft, there may be a burr around the set screw hole on the inside of the knob. If so, use a round file to remove the burr. That should take care of the problem.) With all the knobs in place, the box is shown in Figure 71.

Assembling the trigger cable


The trigger cable will give you the freedom to sit beside your camera, punch the trigger button, and let the process of releasing drops and taking pictures to unfold as you watch the photos appear on your camera's LCD screen. For the assembly, you'll need the 3.5mm mono plug, the remaining push button, and the remaining 3-ft of 2-conductor cable. You'll also need something to mount the push button on. We used a film canister, because that was handy. We'll start by showing you the completed cable in Figure 72. This would plug into the TRIG jack of the controller box.

  1. Figure 73 shows how the 2-conductor cable is connected to the switch. First, two 1/4" holes were drilled, one in the base of the film canister and the other in the lid. The switch was bolted onto the lid, and the red and black conductors soldered to the switch. An overhand knot was tied in the cable to serve for strain relief, and the free end of the cable was threaded through the hole in the bottom of the canister.
  2. Figure 74 shows a different assembly in which a section of PVC pipe with end caps is used. This method provides a larger, sturdier grip. Your choice or design your own.
The trigger cable

The switch mounting

PVC push button  

Figure 72. The trigger cable

Figure 73. The switch mounting

Figure 74. A different version of the trigger cable



  1. Do the following to connect the 3.5mm plug to the free end of the cable.

3.5mm mono plug

Photo 1


See Photo 1 for the 3.5mm mono plug that you'll connect to one end of your cable.

Photo 2

Remove the jacket from the plug 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". See Photo 2.

Photo 3

Insert the stripped wires into the holes on the terminals of the 3.5mm mono connector. The red wire goes in the shorter terminal as shown in Photo 3. Don't crimp the metal tabs around the cable yet, as this will cause the insulation to melt when you solder.


Photo 4

Solder the connections. Since there's so much metal, it will take some time for the soldering iron to heat the metal. Tin the tip of the soldering iron with solder first. Then 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. The completed solder job is shown in Photo 4.

Photo 5

Clip off any stray wires and then crimp the metal tabs around the gray cable as shown in Photo 5.

Photo 6

The completed connector is shown in Photo 6.


Back to top




If you need to assemble a valve kit, go here first. Then return to this page for testing.


Test first without a valve connected. Flip the 3 switches to the off positions and turn the knobs to their minimum positions at 8 ms. Plug the trigger cable into the TRIG jack. If you're using one of our 12VDC adapters, plug it into the 12V IN jack. If you're using your own power supply, make sure it provides a regulated 12V up to 2A.


Test 1. Flip the power switch ON. The LED beside the switch should light continuously. Nothing else should happen.


Test 2. Press the trigger button. The Pulse 1 LED should light momentarily and be quite dim. Turn up TIME ON for Pulse 1 to 60 ms and press the trigger. The LED should be brighter this time. This is due to the fact that the LED is lit for a longer time.


Test 3. Flip the Pulse 2 switch ON. Press the trigger. The LEDs for Pulse 1 and 2 should both light this time, Pulse 2 a bit later than Pulse 1. Increase TIME ON for Pulse 2 to 60 ms and TIME OFF for Pulse 1 to 120 ms. Press the trigger. The Pulse 2 LED should now flash about as bright as the Pulse 1 LED. The delay between the flashes should be longer due to the increase in TIME OFF.


Test 4. Flip the Pulse 3 switch ON. Run through the tests as for Test 3 above.


Test 5: Assuming your previous tests worked, turn off the power to the box, and plug a valve into VALVE1. Turn the power back ON. Press the trigger button without changing any of the settings from the previous test. The valve solenoid should actuate three times in succession. You can try changing time intervals to hear the difference in the solenoid clicks.


Test 6: Press the CLEAR button and hold it down. As long as you're holding it down, the solenoid will be actuated. Release the button to release the solenoid.


Test 7: Move the valve to the VALVE2 and VALVE3 jacks in turn. The valve should function the same way in all three valve jacks. If you have more than one valve, you can test them simultaneously.


Test 8 (optional): If you have an oscilloscope, connect it to the TEST port. You'll be able to view the 3 output pulses.


If all of your tests worked, go to the operating instructions to learn more about your drop controller. If some of the tests didn't work, open the box. First make sure you installed the ICs and the fuse. Seriously, that part is often overlooked, and it's the easiest thing to fix. If those parts are in place, make sure the ICs are firmly seated in the correct orientation. Next, examine all your wiring very closely. Check that you made the correct connections, that polarities are right, and that the solder flowed well on the connections, forming no bridges. Don't overlook checking your trigger cable, too. The wiring of the plug tends to be the weakest link. Make sure there are no shorts between the lugs.


Back to top



About Tools Products Activities Galleries Projects Links Contact Facebook LinkedIn flickr
copyright © 1995-2020