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Assembly and Operating Instructions for Kits


Instructions for Building the Delay Timer 2x (DU2x)


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 8 remaining resistors. Solder these as follows: R6 = 22k (red-red-orange), R7 = 1M (brown-black-green); R8,R9 = 680 (blue-gray-brown); R10,R12 = 470 (yellow-violet-brown); R11,R13 = 1k (brown-black-red).

Photo 2a Photo 2b Photo 2c


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 the insertion of the legs. Slip the capacitor down 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 C2, solder, and clip.


Photo 3e: Insert and solder the remaining capacitors: C1,C5 = 0.0047 uf (472); C4,C6 = 0.047 uf (473); C8 = 0.1 uf (104).

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


Step 4. Adding the SCRs to the PCB


Photo 4a: Insert one of the two SCRs 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: Repeat for SCR1. 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 5a Photo 5b Photo 5c


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 Delayed hole as shown in Photo 6g. 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.


Photos 6h,i: Use a knife to expand the punched holes for the Fine and Coarse Delay pots to 5/16 in as shown in Photo 6h. 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. The completed lid is shown in Photo 6i.

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


Adding Components to the Lid of the Project Box

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


Photo 7a. Photo 7a shows the underside of the box lid. Mount the three RCA jacks and the push button in the lower left-hand corner. Note the orientation of the tabs of the RCA jacks.This orientation 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 four 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 four switches mounted, and Photo 7f shows the top side.


LED holder

Photos 7g,h: 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 as shown in Photo 7g. The under side is shown in Photo 7h.


Photos 7i-k: From the under side of the lid, insert each LED into its collar as shown in Photo 7i. Note that one leg of the LED is longer than the other. Orient the LEDs so that the shorter legs are as shown in the photo. 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. When seated correctly, the LEDs will appear as in Photo 7j. The final part of the LED assembly is to place the rings over the collars on the under side and push into place as shown in Photo 7k. (Note that while this photo shows the 2 variable resistors mounted, wait to mount these until the next step.)


Photos 7l,m: The next 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 7l. Mount the pots as shown in the previous 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 7m, place the remaining washer and the nut on the shaft and tighten.


Photo 7n: 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 7o: Push the point of a knife through each of the four 1/8-in holes, also shown in the previous Photo 7n, and make cross cuts. Then push the 4-40 1/4-in bolts into the holes as shown in Photo 7o. The bolts will receive the standoffs later.

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 7m Photo 7n Photo 7o  


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.


Don't solder connections until instructed to do so.


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.


Photo 8c: Here, you'll connect red wires on the lid. Strip back one end of the red wire by 1/2 inch and then form a spiral using a nail as you did before. Slip this spiral down over the longer leg of LED1 as shown in Photo 8c. Cut the wire to the length needed to reach lug 2 of SW2. Strip this end of the wire by 1/4 inch and make the connection. Connect another section of red wire between lug 2 of RV1 and lug 2 of SW2.


Photos 8d: Bend the shorter leg of LED3 down to the side tab of J3 and loop through the hole. Repeat for the connection of the shorter leg of LED2 to J2. See Photo 8d. Next, make the following connections using sections of the white wire. Strip the ends of the wires by 1/4 inch.

  • Lug 1 of SW1 to lug 2 of SW3
  • Lug 2 of SW3 to lug 1 of J6
  • Lug 1 of J6 to lug 1 of J1
  • Lug 1 of J1 to side tab of J5
  • Side tab of J5 to right lug of PB1

Photo 8e: Strip a small section of wire to use to create a bridge between the side tabs of J2 and J3. See Photo 8e. Then connect a section of white wire from the side tab of J5 to the bridge.


Photo 8f: Cut a section of blue wire and connect it between lug 3 of J1 and the left lug of PB1.


Photo 8g: You may now solder some of the connections. Solder all connections except for the two covered with a red X in Photo 8g. These lugs will have wires added in the next step.

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


Connecting the Jumper Wires and Battery Holder to the Lid

Step 9. Connecting the jumper wires and battery holder 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 LED, 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.


Photo 9a:

  • Cut a 1-in section of blue wire. Strip back 1/4 inch on one end and 1/8 inch on the other. Connect the longer stripped end to lug 3 of J1 as shown in Photo 9a.
  • Cut a 1.5-in section of white wire and strip it as you did for the blue section. Connect the longer stripped end to the bridge between jacks J2 and J3.
  • Cut a 2.5-in section of green wire. Strip one end by 1/8 inch. Strip the other end by 1/2 inch and wrap it into a spiral around a nail. Slip this spiral over the longer leg of LED2.
  • Cut a 2.5-in section of yellow wire. Strip it as you did the green wire above. Slip the spiral over the longer leg of LED3.

Photo 9b: As you continue to cut and strip wires, strip one end by 1/4 inch and the other by 1/8 in. The longer stripped end will connect to the component on the lid. The shorter stripped end will be connected to the PCB in Step 10.

  • Cut and strip two sections of yellow wire to 2 inches each. Connect one section of lug 3 of J6 and the center lug of J3.
  • Cut and strip two section of green wire, one to 1 inch and the other to 1.5 inch. Connect the 1-in section to the center lug of J5 and the 1.5-in section to the center lug of J2.

Photo 9c: Cut 2.5-in sections each of yellow, blue, and green wire. Connect these sections to J4 as follows: green to lug 1, blue to lug 2, yellow to lug 3.


Photo 9d: Complete the jumper wire connections as follows.

  • Cut and strip a 2.5-in and a 3-in section of green wire. Connect the shorter section to lug 1 of SW2 and the longer section to lug 1 of SW4.
  • Cut and strip a 2-in and a 3-in section of yellow wire. Connect the shorter section to lug 3 of SW4 and the longer section to lug 1 of SW3.
  • Cut and these sections of blue wire: 2, 2.5, 2.5, 3 in. Connect the 2-in section to lug 2 of SW4, a 2.5-in section to lug 3 of SW2, another 2.5-in section to lug 1 of RV2, and the 3-in section to lug 3 of SW3.

Photos 9e,f: Next, you'll connect the battery holder. First, cut 1.5-in sections 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 9e. Twist the black battery holder wire around the short, black section. Do likewise for the red wires as shown in Photo 9f. Then solder the connections.


Photo 9g: 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 9h: Connect the black wire of the battery holder to lug 2 of SW1 and the red wire to lug 2 of RV1. Before soldering the latter connection, cut and strip a 3.5-in section of red wire. Connect this to lug 2 of RV1.


If you haven't soldered all the connections, do that before continuing to Step 10.

Photo 9a Photo 9b Photo 9c Photo 9d
Photo 9e Photo 9f Photo 9g Photo 9h


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: Screw the 4 standoffs onto the 4-40 bolts that you previously pushed through the lid. You'll begin to solder wires to the PCB next, but first orient them as shown in Photo 10a.


Solder the connections to the PCB as you make them below.


Photo 10b: Orient the PCB as shown. Make the following connections:

  • Blue wire from lug 3 of SW3 to hole A on the PCB
  • Yellow wire from lug 1 of SW3 to hole C
  • Blue wire from lug 1 of RV2 to hole D
  • Green wire from lug 1 of SW4 to hole R
  • Green wire from center lug of J5 to hole S
  • Green wire from LED2 to hole T
  • Blue wire from lug 3 of J1 to hole U

Photo 10c: Continue connecting wires to the PCB holes as follows:

  • Red wire from lug 2 of RV1 to hole E
  • Blue wire from lug 3 of SW2 to hole F
  • Green wire from lug 1 of SW2 to hole G

Photo 10d: Solder wires to holes H to N as follows:

  • Yellow wire from LED3 to hole H
  • Yellow wire from lug 3 of J6 to hole I
  • Yellow wire from lug 3 of SW4 to hole J
  • Yellow wire from center lug of J3 to hole K
  • Blue wire from lug 2 of SW4 to hole L
  • Yellow wire from lug 3 of J4 to hole M
  • Blue wire from lug 2 of J4 to hole N

Photo 10e: Complete the wiring as follows:

  • Green wire from lug 1 of J4 to hole O
  • White wire from the bridge between J2 and J3 to hole P
  • Green wire from center lug of J2 to hole Q

This completes the wiring of the PCB. Note that holes B, V, X, and W are not connected. Continue to refer to Photo 10e for the following:

  • Use the 4 remaining 4-40 bolts to screw the corners of the PCB down to the standoffs.
  • 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. This IC doesn't have a notch, but there is a white dot on the same end as the notch in the socket.


Photo 10a Photo 10b Photo 10c Photo 10d
Photo 10e      


Wiring the Battery Holder and Completing the Assembly

Step 11. Wiring the battery holder and completing the assembly


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


Photo 11c: 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  


Testing and Operation

Step 12. Testing and operation


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 and the Shutter switch set for Instant, the shutter is actuated. The pulse also appears at Cal output. The latter can 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 jack. In addition, if the Shutter switch is set for Delayed, then the camera shutter is actuated.
  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.
timeline for Delay Timer

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

  • On-off switch in the Off position
  • Timeout switch on Long
  • Delay switch on Default
  • Shutter switch on either setting
  • 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.
Delay switch test Turn both delay knobs to maximum and Timeout switch to Short. Press the Test button and note how long the interval is between the Instant and Delayed LEDs. Now flip the Delay switch to the Divide by 10 position. Press the Test button. This time the delay interval should be much less. That's because the Delay switch divided the delay interval by 10. In this case, the range of the Fine Delay is 0 to 5 ms, and that of theCoarse Delay 0 to 50 ms. For typical operation, put the Delay switch in the Default position.
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 2x




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