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Assembly and Operating Instructions for Kits


Instructions for Building the Delay Timer 2s (DU2s)


Assembly instructions for other kits


Delay Timer 2s




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


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


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



Tools that you'll need


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

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

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

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

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

  6. A lighter or matches to shrink heat-shrink tubing, if the project requires it.

  7. A drill motor and these drill bit sizes: 3/32, 1/8, 1/4, 5/16 in

  8. Small round file
  9. Rubber or contact cement to affix the label to the project box lid

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


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


Adding Components to the PCB

Step 1. Adding the IC sockets to the PCB


Photo 1a: This photo shows the PCB for the project. Note that the label on the board may be either DU2 v1a or DU2 v1b. The assembly instructions are the same for either version.


Photo 1b: Rotate the PCB 180 degrees in order to match the orientation in Photo 1b and successive photos. Two sockets, 8-pin and 14-pin, will be soldered to the board. Note in the photo how the notch in the end of a socket corresponds to the notch in the corresponding figure on the PCB.


Photo 1c: The photo shows the underside of the PCB. Crimp the pins of the sockets over in order to hold the sockets in place and prepare for soldering.


Photo 1d: Solder the pins, being careful not to bridge solder between pins. If this happens run the tip of the soldering iron between the pins to remove the bridge. This may take several tries.


Photo 1a Photo 1b Photo 1c Photo 1d


Step 2. Adding the resistors to the PCB


Photo 2a:1k-ohm resistor Start with the 100k resistor (see photo to the right). The resistance value is indicated by the sequence of band color, brown-black-yellow in this case. Insert the legs of the resistor into the location labeled R3 on the PCB. Note that the resistors aren't polar and can be placed in either of the two possible orientations. Repeat for R4 (1k = brown-black-red) and R5 (red-red-orange).


Photo 2b: Solder the legs of the 3 resistors to the back side of the PCB and then clip off the excess. The completed solder connections, surrounded by a yellow box, are shown in the photo.


Photo 2c: There are 7 remaining resistors (see Note 1 below). Solder these as follows: R6 = 22k (red-red-orange), R7 = 1M (brown-black-green); R8,R9 = 680 (blue-gray-brown); R12 = 470 (yellow-violet-brown); R11,R13 = 1k (brown-black-red). When you snip the legs, save two of the snipped pieces for the next step.


Note 1: R10 is X'ed out in Photo 2c, because this resistor is not supplied and used in this version of the Delay Timer. Ignore the placement of R10 in Photo 2c and remaining photos.


Photo 2d: For the snipped legs that you saved in the last step, bend each leg in a U-shape. Insert one piece between holes B and C and the other between holes V (see Note 2 below) and W. Then solder in place on the back of the board.


Note 2: By connecting holes V and W, the shutter output will become an instant output. If, however, you prefer that the shutter output be a delayed output, then connect holes X and W instead. If you're unsure what you prefer, connect V and W now. Later, if you want a delayed shutter, this can be done by using the Pulse Delayed output in conjunction with the Opto Switch 2 accessory. For more information, see the Pulse Outputs section of the Delay Timer 2s operating manual.

Photo 2a Photo 2b Photo 2c Photo 2d


Step 3. Adding the capacitors to the PCB


Photos 3a,b: Select the 0.47-uf capacitor as shown in the photo. Note in Photo 3a that one leg is longer than the other. Insert the capacitor into the holes for C3 with the longer leg in the hole marked +. See Photo 3b showing how the body of the capacitor is positioned close to the board. Solder the legs under the board and clip.


Photo 3c: Insert the 10-uf capacitor into the holes for C7, again with the longer leg inserted in the + hole. Solder and clip.


Photo 3d: The remaining capacitors do not have polarity, so the legs can be inserted in either hole. Insert a 0.047-uf capacitor (marked 473) in the holes for C4, solder, and clip.


Photo 3e: Insert and solder the remaining capacitors: C1,C5 = 0.0047 uf (472); C6 = 0.047 uf (473); C8 = 0.1 uf (104). Note that C2 is not used.

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


Step 4. Adding the SCR to the PCB


Note that there is only one SCR supplied with the Delay Timer 2s kit. While the photos below show 2 SCRs, SCR1 is X-ed out. Do not install SCR1.


Photo 4a: Insert the SCR into the location labeled SCR2 on the PCB. Align the flat side of the SCR with the corresponding shape on the board. Push the component down to seat the legs firmly. Solder the legs on the underside of the PCB. Avoid overheating the SCR as damage could be caused to the component. If you take too long soldering on a particular leg, wait for the SCR to cool before moving onto to another leg. Be careful to avoid bridging the solder between legs. Clip the protruding legs when finished.


Photo 4b: The completed PCB is shown in the photo. The ICs will be added to the sockets later.

Photo 4a Photo 4b


Preparing the Project Box

Step 5. Drilling the lid and the bottom of the box


Note that Photos 5a-c show the veiw from the underside of the project box lid.


Photo 5a: Cut out the drilling template and place it in the underside of the project box lid. Using a hammer and a sharp, pointed instrument such as a large needle or a punch, mark the centers of the holes on the template.


Photo 5b: Remove the template. Drill 3/32-in starter holes at each of the locations that you marked.


Photo 5c: Drill the starter holes to the sizes indicated on the template. Note that the hole marked Test is for the push button, which is actually a little larger than 1/4 in. If you have a 9/32-in bit use that to drill the hole. Alternatively, use a file or sharp knife to widen the hole. Check the size by trying to insert the push button.


Photo 5d: This photo shows the top side of the lid with holes drilled.

Photo 5a Photo 5b Photo 5c Photo 5d


Step 6. Adding the label


Photo 6a: Trim around the black border of the lid label. A stencil or razor knife with a straightedge will help to get straight cuts, but sharp scissors will also serve.


Photo 6b: Pull the backing off one of the laminate sheets, and lay the sheet, sticky side up, on a table. Carefully place the lid label, label side down, onto the sticky side of the laminate sheet. In order to avoid getting air bubbles, apply the shorter edge of the label first and gradually push it down onto the laminate with a finger.


Photo 6c: Remove the backing from the other laminate sheet and carefully apply it, sticky side down, to create a sandwich of the two laminate sheets with the label in the middle. Use the technique described above to avoid getting air bubbles. When the laminate is in place, rub a finger over the laminate and around the edges of the label to ensure a good seal. Finally, use a stencil or razor knife or sharp scissors to trim the excess laminate from around the label. The completed label with laminate applied and trimmed is shown in Photo 6c.


Photos 6d,e: Use a 1/4-in hole punch to punch out the 1/4-in and 5/16-in holes on the label as shown in Photo 6d. If you don't have a hole punch, the point of a sharp knife can be used to carve out the holes. Don't worry if some edges are ragged. These will be covered by the components later. The label with holes punched is shown in Photo 6e. The 1/8-in holes will be punched later.


Photos 6f,g: Now it's time to glue the label to the top of the lid. First cut the 2-in section of plastic tubing into two 1-in pieces. For glue, use rubber cement or other repositionable adhesive. Spread the adhesive over both the lid (as shown in Photo 6f) and the under side of the label (not shown). Place the label in position on the lid, and align it using the two pieces of plastic tubing. Push one piece of tubing through the Power (On-Off) hole and the other through the Flash hole. Flatten the label by rubbing a finger over it and hold in position for a minute or so to insure adhesion. Then carefully remove the plastic tubing to avoid shifting the position of the label. Any glue that extends beyond the edge of the label can be rubbed off with a finger. If there is glue smeared on the label that can't be rubbed off, use a mild solvent such as denatured or rubbing alcohol and a soft, clean cloth to clean the label. Finally, place the label under a stack of books or other weight to press it for a few hours. When completed, the lid with label should look like Photo 6g.


Photo 6h: Use a knife to expand the punched holes for the Fine and Coarse Delay pots to 5/16 in. Then check the under side of the lid to see if portions of the label overlap any of the 1/4-in holes. If so, use a stencil knife, razor, or knife blade to trim the label back to the boundaries of the hole. This will make it easier to insert components later.

Photo 6a Photo 6b Photo 6c Photo 6d
Photo 6e Photo 6f Photo 6g Photo 6h


Adding Components to the Lid of the Project Box

Step 7. Adding the jacks, switches, pots, and LEDs


Photo 7a. The photo shows the underside of the box lid. Mount the two RCA jacks and the push button in the lower left-hand corner. Note the orientation of the tabs of the RCA jacks.While this orientation isn't essential, it will help in wiring later.


Photos 7b,c: Mount the two 3.5mm mono jacks (cream colored) and the 3.5mm stereo jack (black) in the locations shown. Orient the tabs as shown in Photo 7b. Photo 7c shows the upper side of the lid with the components mounted so far.


Photos 7d-f: The two switches will be mounted next. In Photo 7d showing a switch, notice the ring with the tab pointing toward the base of the switch. When you mount the switch on the lid of the project box, point the tab the opposite direction. Then when you insert the switch through the 1/4-in hole on the under side of the lid, the tab will slip into the 3/32-in hole, serving to prevent the switch from turning. Photo 7e shows the underside of the lid with the two switches mounted, and Photo 7f shows the top side.


LED holder

Photos 7g-i: The LED holder has two parts shown to the right. The first step in mounting an LED is to snap the collar of the LED holder into the hole from the upper side of the lid. Then, from the under side of the lid, insert each LED into its collar as shown in Photo 7g. Note that one leg of the LED is longer than the other. Orient the LEDs so that the longer leg is the one nearer the outside of the lid. Push each LED into the collar until the LED snaps into place. This may require quite a bit of force, depending on how tight the fit is. You can use a small, blunt instrument to push on the base of the LED until you hear it snap into place. The final part of the LED assembly is to place the ring over the collar on the underside and push it into place as shown in Photo 7h. Photo 7i shows the lid from the top side with the LEDs mounted.


Photos 7j-l: The final components to mount are the variable resistors, also known as potentiometers or pots. Note that there are 2 washers under the nut. Remove the nut and one of the washers. Note also that there's a metal tab beside the shaft. We recommend snipping off about one-third of the tab so that it doesn't create an indentation in the lid label when mounted. See Photo 7j. Mount the pots as shown in Photo 7k, being sure to mount the 1M and 100K pots in the indicated locations. These are different values and are not interchangeable. On the top side of lid, shown in Photo 7l, place the remaining washer and the nut on the shaft and tighten.


Photo 7k. Before adding the knobs, turn the shafts of the pots all the way counterclockwise. This is the 0 position. Loosen the set screw on each knob and mount on the shafts with the white indicator mark pointing to zero. Tighten in place.

Photo 7a Photo 7b Photo 7c Photo 7d
Photo 7e Photo 7f Photo 7g Photo 7h
Trimming the height of a tab
Photo 7i Photo 7j Photo 7k Photo 7l
Photo 7k      


Wiring the Project Box Lid

Step 8. Wiring the resistors and component-to-component wires


Refer to this graphic to identify pins and part IDs in wiring the lid. Note that the black wires shown in the graphic are white wires in actual use.


Photos 8a,b: Two of the resistors are wired between components on the box lid. Start with the remaining 1k (brown-black-red) resistor. Wrap about half an inch of one end of the resistor around a small nail as shown in Photo 8a. Then remove the nail. It will now be easy to lower the spiral over a leg of an LED. Connect the resistor between the shorter leg of LED1 and lug 1 of switch SW1 shown in Photo 8b. Next, connect the remaining 470 ohm resistor (yellow-violet-brown) from lug 1 of pot RV1 to lug 2 of pot RV2. Again, see Photo 8b. Don't solder connections yet; this will be done after the wiring on the lid is complete.


Photos 8c,d: Bend the two shorter legs of LED2 and LED3 down until they are parallel to each other as shown in Photos 8c and 8d. Also, bend the longer leg of LED1 over to connect to lug 2 of switch SW2. Also see Photo 8d.


Photo 8e: The white wires (this is the ground) will be connected next. See Photo 8e. Cut and strip the needed lengths to make the following connections. Again, refer to the wiring graphic for designations of the components and pins/lugs.

  • Lug 1 of SW1 to lug 1 of J6
  • Lug 1 of J6 to the parallel legs of LED2 and 3
  • Parallel legs of LED2 and 3 to lug 1 of J1
  • Lug 1 of J1 to side tab of J5
  • Side tab of J5 to side tab of J3
  • Side tab of J3 to right lug of PB1

Photo 8f: Two wires remain. Connect a length of red wire from lug 2 of RV1 to lug 2 of SW2. Connect a length of blue wire from lug 3 of J1 to the left lug of PB1.


Photo 8g: You may now solder some of the connections. Solder only those connections circled in yellow in Photo 8g. In the next section, you'll add jumper wires to the unsoldered connections.

Photo 8a Photo 8b Photo 8c Photo 8d
Photo 8e Photo 8f Photo 8g  


Connecting the Jumper Wires to the Lid

Step 9. Connecting the jumper wires to the lid


The wires that you'll add in this step are connected to components on the lid on one end only. The other end will be connected to the PCB in Step 10. Continue to refer to this graphic to identify pins and part IDs.


Except as indicated below, you may now solder wires as you connect them below or wait to solder until finished with all connections. When you solder the longer leg of each of LED2 and LED3 and the shorter leg of LED1, solder near the base of the LED and then clip off the excess leg length. Also, make sure that the two legs of each of the three LEDs are well separated in order to avoid shorts.


Photos 9a: Cut 4 sections of blue wire to these lengths: 1, 1.5, 2.5, 2.5 inch. Strip back one of the 2.5-in section by 1/2 in on one end. Wrap this end around a nail as you did for the resistor in the last step (Photo 8a). Then slip the spiral wire down over the longer leg of LED 2 as shown in Photo 9a. Strip the remaining sections of blue wire back by 1/4-in on one end. Connect these as follows (also Photo 9a):

  • 1-in section to lug 2 of J4
  • 1.5-in section to lug 3 of J1
  • 2.5-in section to lug 1 of RV2

Photo 9b: Cut 5 sections of yellow wire to these lengths: 1, 1, 2, 2, 2.5 inch. Strip back a 2.5-in section by 1/2 in, wrap it into a spiral, and slip it down over the longer leg of LED3 as shown in Photo 9b. Strip the remaining sections of yellow wire back by 1/4-in on one end. Connect these as follows (also Photo 9b):

  • 1-in section to center lug of J5
  • 1-in section to lug 3 of J4
  • 2-in section to lug 3 of J6
  • 2-in section to lug 1 of SW2

Photo 9c: Cut 3 2-in sections of green wire. Strip each section back by 1/4 in on one end. Connect these as follows (Photo 9c):

  • Lug 1 of J4
  • Center lug of J3
  • Lug 3 of SW2

Photo 9d: Cut a 1.5-in section of white wire and a 3.5-in section of red wire. Strip these back by 1/4 in on one end. Connect as follows (Photo 9d):

  • White wire to the side lug of J3
  • Red wire to lug 2 of RV1 (Do not solder this connection until later, as there will be one more wire to connect here.)
Photo 9a Photo 9b Photo 9c Photo 9d


Connecting the Jumper Wires to the PCB

Step 10. Connecting the jumper wires to the PCB


Continue to refer to this graphic to identify pins and part IDs.


Photo 10a: Strip back all the jumper wires to 1/8 in on their free ends. These are the ends that you'll insert into the holes on the PCB. You'll need to solder these connections as you go to keep the wires from slipping out of the holes. Orient the PCB as shown in Photo 10a, and make these connections.


  • Blue wire from lug 3 of J1 to hole U on the PCB
  • Yellow wire from the center lug of J5 to hole S

Photos 10b,c: This is a good time to add the standoffs to the lid so you can weave wires around them as necessary. Use a knife or pencil to punch through the four 1/8-in holes at the corners of the gray rectangle on the PCB label as shown in Photo 10b. Push the four 1/4-in 4-40 bolts through these holes and screw on the standoffs on the reverse side of the lid. See Photo 10c with the standoffs in place.


Photos 10d,e: If you haven't already done so, clip off the longer leg of LED2 and LED3 above the solder. Continue connecting wires to the PCB holes as follows:

  • White wire from side lug of J3 to hole P
  • Green wire from center lug of J3 to hole K
  • Green wire from lug 1 of J4 to hole O
  • Blue wire from lug 2 of J4 to hole N
  • Yellow wire from lug 3 of J4 to hole M

Photo 10e shows the board from above with holes K, M, N, O, P, S, and U soldered.


Photo 10f: Solder wires to the remaining holes as follows:

  • Blue wire from the longer leg of LED 2 to hole T
  • Yellow wire from lug 3 of J6 to hole I
  • Yellow wire from the longer leg of LED3 to hole H
  • Yellow wire from lug 1 of SW2 to hole G
  • Green wire from lug 3 of SW2 to hole F
  • Red wire from lug 2 of RV1 to hole E
  • Blue wire from lug 1 of RV2 to hole D

This completes the wiring of the PCB. Note that holes A, J, L, R, Q, and X are not connected.


Photo 10g: Bolt the PCB to the standoffs using the remaining four 4-40 bolts. Next, insert the 556 timer into the socket. Make sure that the notch in the end of the timer aligns with the notch in the socket and that all the legs go into their respective holes. Then push the IC down firmly. Repeat for the PS2501 optocoupler (see Note below). This IC doesn't have a notch, but there is a white dot on the same end as the notch in the socket.


Note: The photo shows two single optocouplers mounted in the socket. The optocoupler supplied with your kit is a dual IC and takes the place of 2 separate ICs. See Photo 10h for the dual optocoupler.


Photo 10a Photo 10b Photo 10c Photo 10d
Photo 10e Photo 10f Photo 10g Photo 10h


Wiring the Battery Holder and Completing the Assembly

Step 11. Wiring the battery holder and completing the assembly


Photos 11a,b: Cut a 1.5-in section of black and red wire. Strip each wire back half an inch on one end. Also strip the red and black wires of the battery holder by the same amount. See Photo 11a. Twist the black battery holder wire around the short, black section. Do likewise for the red wires as shown in Photo 11b. Then solder the connections.


Photo 11c: Cut two 1-in sections of the 3/32-in heat shrink tubing and slip over the soldered connections. Use a lighter or match to shrink the tubing. Note that the purpose of these extensions is to make the wire ends less likely to break when the lid is removed for battery replacement.


Photo 11d: Connect the black wire of the battery holder to lug 2 of SW1 and the red wire to lug 2 of RV1. Then solder both connections.


Photo 11e: Position the battery holder in the bottom of the project box as shown in the photo. Use the supplied hook-and-loop tape to affix the battery holder securely to the bottom of the box.


Photo 11f: If the power switch of the box is on, turn it off. Then insert a fresh battery into the battery holder.


Photo 11g: Place the lid on the box, being sure to seat it completely without any wires being pinched. Then the screw down the 4 corners of the box.

Photo 11a Photo 11b Photo 11c Photo 11d
Photo 11e Photo 11f Photo 11g  


Testing and Operation

Step 12. Testing and operation

timeline for MT3


Before beginning tests, the diagram of the timeline shown to the right may help in understanding how the timing works.

  1. When a trigger pulse is received at the Input jack, the 556 timer produces its first output pulse (called Output Pulse 1 (in the diagram). At the same time the Instant LED lights. If a camera is connected, the shutter is actuated. The pulse also appears at the Cal output which could be used for optional calibration using an oscilloscope.
  2. Output Pulse 1 remains high for a length of time determined by the settings of the Fine and Coarse Delay knobs. At the end of this time, the Instant LED goes out, and the Delayed LED turns on. This is the beginning of Output Pulse 2. At this time, a flash connected to the Flash jack will be actuated, and Output Pulse 2 appears at the Pulse Delayed jack.
  3. Output Pulse 2 remains high for a length of time determined by the setting of the Timeout switch. During this time, the Delayed LED remains on, and the flash or camera cannot be activated.
Below are some tests you can perform to see if the box is working correctly.

Begin your tests with the switches and knobs in the following positions.

  • On-off switch in the Off position
  • Timeout switch on Long
  • Fine Delay at 0
  • Coarse Delay at 500 ms
Power test Switch on the power. The Power LED should light and remain lit.
Trigger test Press the Test button momentarily. The Instant LED should light and remain lit for about half a second. Then the Delayed LED will light and remain lit for about one second.
Coarse Delay test

Turn the Coarse Delay to 250 ms. Press the Test button. The Instant LED should remain lit about half as long (0.25 s) as in the previous test. Now turn the Coarse Delay to 0 and press the Test button. The Instant LED should be so brief as to hardly be visible.

Fine Delay test Turn the Fine Delay to 50 ms and press the Test button. The Instant LED should be brighter than when the Fine Delay was 0, indicating that the delay interval increased.
Timeout test Flip the Timeout switch to Short and press the Test button. The Delayed LED should light only momentarily. This indicates a minimal timeout.
Completion Turn the power off. If the box passed all the tests, you're good to go. If not, open the box and check your solder connections to make sure you didn't overlook any. Check that the solder flowed well rather than beading and that there are no stray wires. Check that the ICs are oriented correctly and seated well.


Go to Operation of the Delay Timer 2s




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