Designing An Electronic Trigger For A Paintball Marker To Allow User Selectable Firing Rates Team WTR

Overview  Design and implement an electronic trigger  Upgrading is more practical compared to other high end electronic markers  Target customers will be scenario paintball enthusiasts  Principal expense is development cost

Design Objectives  Electronic trigger upgrade for the 98 Custom paintball marker  Two firing modes: semi-automatic and fully automatic  LCD screen will display the mode  LED indicator for low ammunition and selected firing mode  User friendly up/down buttons to change the rate of fire

Completed Design

Top Level System Design

Selection - Modes  Off mode – Turns all the electrical components on  Semi mode – Fires the marker one time per trigger pull  Full mode – Fires the marker until the release of the trigger

Indication - LED  Semi Mode: Green LED  Full Mode: Red LED  Low Ammo Status: LED alternates RED and GREEN

LCD Module  Semi Automatic – Display “SA MODE”  Full Automatic – Displays “FA MODE”  Low Ammo – Displays “LO AMMO”

Change – Rate of Fire  Two pushbuttons implement adjustable rates of fire  One pushbutton increases the rate  One pushbutton decreases the rate  Pressing both simultaneously clears the low ammo status, indicating a reload.

Trigger Assembly  Trigger is pulled, sending signal to PIC  Depending on firing mode and firing rate, PIC fires solenoid appropriately.  Solenoid drives sear rod up into sear pin, rotating it such that the bolt is released, thus firing the marker.  Blowback resets bolt, sear assembly.

PIC Controller/ Environment  20 pins – 1 VDD, 1 VSS, up to 18 I/O pins  Operates on V  Up to 20MHz oscillator/clock  Up to 200ns instruction cycle  8-bit and 16-bit timer/counters  MPLAB Integrated Development Environment (IDE) included as tool to program PIC  MPLAB is programmed in assembly language  PIC Kit 2 software responsible for debugging code and loading chip

Advantages of Design Other Trigger Designs WTR.98 Custom Not implementedImmediate trigger lock upon ammunition depletion, conserving valuable air supply PC board has to be reprogrammed Able to change rate of fire efficiently using up/down pushbuttons Nothing to communicate selected settings to operator LCD module gives quick user feedback on settings Other trigger controls are not intuitive to use Design focused on user friendly features

Costs

Improving Marketability  Today’s high end electronics enable projects to be assembled much more compactly. Compiling the WTR into a much smaller package has obvious benefits.  Moving the battery into the WTR electronics unit would allow for quicker and faster battery replacements.  Displaying actual ammunition levels on the LCD could better influence the operators judgment in pre-engagement reloading opportunities.

Yet To Be Completed…  Team WTR was unable to provide the solenoid with enough power to successfully discharge the heavily weighted firing bolt in the 98C marker. NOTE: The bolt IS NOT the sear. The sear pin was successfully activated.  More efficiently fitting electronics into the enclosure.