mount. Follow the holes cut out from the template for the
DIN jack. Drill the screw holes with a 1/8” drill. They will
self-thread using 1/4” 6-32 screws.
Using the display box template attached to the top of
the lid, drill the holes as marked. A 1/16” hole is drilled for
the light sensor aperture. The 1/16” pin holes should be
12” from each other.
Glue the template to the 3/4” blocks using a glue
stick. Place them into a vice and tilt the blocks so that the
drill is parallel to the 3/64” drill line. This line will correct
for the angle of the rods. Drill to a depth of 1/2”. Remove
the templates with hot water, then either use a hot glue
gun or Gorilla glue and attach each block to the inside of
the top of the box. Use the diffusers to insure that the
blocks are properly positioned so that the diffusers are
aligned parallel to the ends of the box. Remove the
diffusers immediately to prevent them from
being glued in the holes. Solder the
Pin 1: Battery red wire from battery holder
Pin 2: White 4” wire (signals from sensor 1)
Pin 3: Short wire to pin 6 (ground)
Pin 4: Yellow 4” wire (signals from sensor 2)
Pin 5: Sensor 1 red 12” wire (five volts regulated)
Sensor 2 red 16” wire (five volts regulated)
Pin 6: Black from battery holder (battery ground and
Sensor 1 green 12” wire (sensor 1 ground)
Sensor 2 green 16” wire (sensor 2 ground)
Pin 1: 12” white wire
Pin 2: 16” yellow wire
Pin 3: 4” white wire coming from the DIN
Pin 4: 4” yellow wire coming from the DIN
Pin 5: 12” blue wire
Pin 6: 16” black wire
Pass the wires through the strain relief holes of the
sensors and solder the wires to the sensors on the
appropriate pads. The blue wire goes to the TP1 of sensor
1. The black wire goes to TP1 of sensor 2.
Mount the sensors to the top inside of the box using
one 3/8” spacer and two 1/2” 6-32 screws. The pot will
act as a spacer (refer to Figure 3).
Plug the nine volt battery into its holder and affix it to
the box with double-sided tape. Screw the bottom to the
top of the chassis.
Place a strip of either red or yellow vinyl tape
between the sensors and on the end where the DIN jack
March 2017 21
■ FIGURE 3. Chronograph, inside view.
■ DIN jack.
■ FIGURE 4. Chronograph, top view.
■ FIGURE 2. Chronograph boards.