Sometimes driving my cat crazy with a laser pointer just doesn't cut it. On occasion it would be nice to pre-occupy myself with delusions of adventure and a dynamic outdoor activity.

The project uses a modified squirt gun with a pulse modulated laser and a receiver target detector and display. The assemblies are based on both Microchip 12F509 and an Arduino-based Pro Mini controller. The project works as a stationary target game, but some enterprising individual could easily adapt it to create their own home version of laser tag.

Okay, maybe not that epic, but you get the idea.

BUILD INSTRUCTIONS

It begins with a toy squirt gun, shown above. The water bladders and trigger tubing were removed and the battery pack, taken from a relatively familiar flashlight assemble was fitted, in his case and glued into the best opportunity provided by the plastic squirt gun body, providing the 3-AAA holder and base mounted switch integrated to the plastic frames. This is the orange/red end shown in the figure.

The remaining hardware is a simple push button used to trigger the MicroChip based controller and generating a multi-pulse laser beam. The pulse if made of 3 consecutive, 50ms, modulated pulses using 60% duty cycle and was coded to repeat with a small gap of 0.15 seconds if the button was not released.

The second laser gun, shown below, was also assembled. It came with its own trigger, light and sound electronics. Because the electronics was only 3 volts I adapted the controller and driver with a photo resistor to detect and trigger off the original toy’s light flashes. The sensor electronics for this second gun is identical to the target application.

I used a laser pointer for the laser sources. Both laser assembly designs and the target hardware were therefore nicely integrated with the toys and the display. The flashlight is an inexpensive unit and includes the battery holder used for the pulsed laser guns.

Admittedly I was fortunate to find such an accommodating toy gun and it has been a few decades since I actually went looking for one.

The target module uses an inexpensive, battery based, LED fixture.

The target assembly uses the 3 AAA batteries and its on/off switch, integrated into the fixture base.

This target module includes the sensor and display uses an Arduino Pro Mini controller. The power LED and the L05 regulator were removed. The display assembly, shown in the photos, use a minimum of parts and includes a photo-resistor, the controller and only a handful of LED and resistors. The controller was programmed for minimum current and exploits a sleep library power down request.

The sensor is initially enabled ~every 34ms, the sensor is enabled and the ambient light level is evaluated. This completes in less than 0.5ms. Any detected pulses are then monitored every 500μs to identify a single laser pulse of the correct frequency and duty cycle. This requires the laser to be on target at least a 55ms during its 3 pulse cycle.

The power profile below was generated using a 10 ohm resistor, measuring <10.13ma peak, for 293μs every ~35ms,

The display burst includes 6 LEDs in a rotating and radiating pattern. This is functionally a compromise between effect and power. Several pins are available, allowing the possibility of a more verbose display. When averaged the target consumes < 150uA and is dependent on battery voltage. The fixtures on-off switch is also provided.

Considering the power related issues, the display driver and packaging resolution used for the project, the implementations has several solutions which could also be valuable in other projects. While it is based only on a small laser pointer, either stand alone or with the included target module it is enough to provide a nice diversion to boring commercials, pesky flies, that have lighted on the wall or for cats that your came with your spouse.

While not particularly suitable for children, the finished project was a hoot and a half.

PARTS LIST

Part Quantity Digi-Key Part # 39 ohm resistor 1 CF14JT39R0CT-ND 620 ohm resistor 6 CF14JT68R0CT-ND 1K ohm resistor 1 CF14JT1K00CT-ND 100 ohm resistor 1 CF14JT100RCT-ND photosensor (or similiar) 1 PDV-P8104-ND Arduino MiniPro controller (or equivalent) 1 10uF capacitor 1 732-6367-3-ND laser pointer 1 1N4148 diode 1 1N4148FS-ND SPST momentary/NO 1 dependent on water gun SPST toggle 1 optional/ reused from light fixture 12F509 controller (or SOIC) 1 PIC12C509A-04I/P-ND HiEffec WHT LED (or other HI effecient) 1 C503B-RCN-CW0Z0AA1-ND

CLICK HERE TO DOWNLOAD THE PROJECT SOURCE CODE.

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