bored or drilled the hole for the laser, it was still off from
the sights. I discovered that this was due to the laser
manufacturing alignment itself. I decided to add an
■ FIGURE 6.
positive wire going to the last battery and to access
9. Drill three #43 holes at 120 degrees 1/8” from the
end of the knurled end and tap with a 4-40 tap.
Place three 1/8” 4-40 set screws into the tapped
10. Using electrical tape, wrap the last 1/8” to 1/16”
of the proximal end of the laser. This will act as a
pivot. It can also act as a shim by cutting part of
the tape off.
One of the problems I encountered was that if I either
Mill or drill press
1/16” End Mill
■ Gunsight Schematic.
The photon emitter uses an inexpensive laser diode
(<$10) which is powered by five #10 hearing aid batteries.
The detection circuit uses a sub-miniature microphone.
When the trigger is pulled, the firing pin causes a click
that the microphone picks up. Its output feeds into a
PIC12F508 which then pulses the laser for 50
milliseconds. R3 limits the laser’s output. This prevents
lock-up. The whole detection system is soldered to a
1” x .225” board (see Figure 4).
Solder the microcontroller to the board noting pin 1,
the two 10K resistors, and the .01 capacitor. The
microphone is soldered from the top of the board to the
square pin with pin 1. Cut the speaker leads short and file
or sand so than you can mount the switch to the back of
the board. R3 is soldered to the back of the board along
with the micro-switch. Using a piece of 1/4” solder braid,
fill with solder and bend at a 90 degree angle. Solder this
braid to the top and bottom square pads next to the
microphone. This will act as the negative contact for the
batteries. Carefully cut the wires from the laser to about
3/8” and strip. Solder the red wire from the laser to the
square pad next to the chip. Solder the black wire to the
round hole. Using a 1” piece of red wire wrap, solder it to
the pad next to the solder braid. With the slot and the
switch up, thread the wire, board, and the laser from the
knurled end. The laser should be flush to the end of the
tube. Tighten the Allen screws. The red wire runs along
the slot. Trim the red wire to the end of the tube and
solder the small brass washer to it (see Figure 5). The
switch should be visible.
Use a spring from a ball point pen and cut to a length
of 1/4”. Place five batteries into the tube with their
negative ends toward the board. Put the washer on the
last battery, add the spring, and screw the set screw into
the tube. Turn on the switch and tap the
tube on the table. The LED should pulse on
The microcontroller goes to sleep and
wakes up when it detects the click.
However, the two 10K resistors will pull
250 uA. The batteries produce 75 mAh.
However, when the laser fires it pulls about
25 mAh for 50 milliseconds.
Insert the laser tube into the barrel of
the gun. The knurled end should be flush