Arduino Technology
Arduino Nerf sentry gun build: wiring the trigger

I’m building an Arduino-controlled Nerf sentry gun. Rather than build it and present the finished project all at once, I’m going to chronicle the build here on Make: Online.

The first step was to add wiring and a two-wire connector to control the trigger circuit. I opened up the Nerf Vulcan (about 30 screws) and soldered an 1/8″ female jack to the fire selection mode switch. This way, I can retain all the regular functions of the gun when it’s unplugged from the Arduino. To control it from the Arduino, I’ll flip the orange switch on top to “off” and then wire the trigger into the “pulled” position (done here with a classy twist tie). Whenever the Arduino’s trigger circuit closes (bypassing that orange “off” switch) the gun will start firing.

To add the connector, I drilled a 1/4″ hole in the gun’s hand grip, fed the sleeve through, and secured it with a couple of zip ties inside for strain relief.

Next, I’m planning to build the Arduino’s trigger circuit using a MOSFET transistor wired to a male 1/8″ jack I can plug into the gun.

In the Maker Shed:



Arduino Duemilanove

30 thoughts on “Arduino Nerf sentry gun build: wiring the trigger

    1. Wow, great job! You guys really built it from scratch, didn’t you. Very impressive. I’m going to lean on the engineers at Nerf for most of the heavy lifting!

      1. We left the barrel and darts to them though…we thought it was good engineering on there part :P

    1. Hey, you totally nailed it PJ! I needed to test out distance measurement as a component of this project. Stay tuned!

  1. You could make a target recognizer system with a camera or a motion dedector and with a couple of servos you can make it turn left -right up and down so as to find the target and shoot them.Can you imagine the how the face of someone being hit from your auto shooting nerf ?

    1. Thanks Theo, I like your thinking. I’m planing to do some motion detection (actually distance sensing) and motorized targeting.

  2. I’m going to lean on the engineers at Nerf for most of the heavy lifting!

    I can’t tell if that’s a joke or not. Is this a “sponsored project” and just not marked?

    1. Hi David, sorry for the confusion, no it’s not sponsored — that was a joke. I bought these guns with my own cash and have no contact with Nerf. What my failed joke meant to convey was that I’m not building my fully-automatic, belt-fed, foam dart gun from scratch, but instead relying on all the great work that they did to build the thing themselves.

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John Edgar Park likes to make things and tell people about it. He builds project for Adafruit Industries. You can find him at and twitter/IG @johnedgarpark

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