NERF Sharpshot Modification #1: Muzzle Flash

[07052012 1309]

 

Muzzle Flash

I just want to do this effect even though it looks corny. What this effect does is to simulate a muzzle flash. The first idea is to use a light sensor which, upon detection of the dart, will ‘flash’ the LEDs. Unfortunately, this would create a new problem as the detection circuit would be using power all the time and as I have said, I will not be putting a power switch outside the gun. And so, because of the space inside the shell, I decided to cheat a little. I will use a micro switch instead.

 

 


The muzzle of the Sharpshot is a separate piece which comes off easily when you split the shell open.

 

This is the view from the other side which as you can see, is hollow. You can easily put in eight 3mm LEDs inside.

 

Although the part looks solid, it allows a lot of light to come through. Here, I am testing with two 3mm White LEDs using my own LED tester.

 

A simple test with the prototype board show that the LEDs are good to go. Because of the minimal voltage, I can actually forego the current limiting resistors but since I had some spare, I decide to use them.

 

This is how I am going to use the 3mm LEDs. The first thing is to solder their negative leads in pairs. What you need to do is to is to first determine how far to bend the negative leads of each LED. This is because although the insides of the muzzle is hollow, there are four plastic walls which reinforces the inner wall of the muzzle. Also, each bent lead must be long enough to be soldered to the next LED’s negative lead to create ring. Start with soldering the first pair of LEDs by their negative leads. Test fit them on the inside of the muzzle part.

 

Once you have the four pairs, join each pair by soldering their negative leads in equal length until you form a closed ring. This will be the negative ring. Do not worry if the positive leads are shorting since we will not be applying power to the LEDs yet.

 

 

The next ring is a bit more tedious as you will need to solder the current limiting resistors. Referring back to the previous picture, note that the positive leads have now been cut short. Take each resistor and cut off one end of the lead about 5mm after the resistor and solder them to the LED’s positive lead. To prevent shorting, insert heat-shrink tubing. Now, bend the other resistor leads to form the second ring, about 3 to 5mm from the first ring. This is the positive ring.

You may now solder the red and black wires to each of the ring.

Using a set of 3x AA (4.5 volts) batteries, test the LED ring. You should get this effect. Bear in mind, in this picture, the effect is brighter than it really is since I have problems taking such photos using digital cameras. Note that although I am using resistors rated for 2x AA (3 volts), I found out that I needed all the 4.5 volts I could get since the second modification uses a lot of power.
 

Inserting it back to the Sharpshot shell, the effect is quite nice. Corny but still nice.

 

This is a rough sketch of what I want to do with the Sharpshot. Note that this is the first draft as the Laser Pointer in the second mod affected my design. The sketch was drawn in such a way that it more or less shows how each component is placed inside the shell. The Ring of White LEDs and Laser Pointer on the left means the gun is pointing to the left. Power will be split into two; the first pair will be at the gun’s forward area while the remaining battery will be at the grip. So are the two micro switches. The next stage is the wiring. Looking back at the diagram, you will see that there are four wires connecting all the components (intersected by the yellow dashes)

The only space available is the narrow area in the trigger mechanism. You cannot use the tube/plunger area since they are moving parts and this will greatly affect either systems. I used a 3mm drill bit to drill through as the wires I am using are quite thin.

There are three walls you need to drill through. In the shot above, you can see the finished result. This is the view as seen from the upper side of the gun.

Once you have pulled the wires through the hole, the next step is to mount the 2x AA battery holder. It is a good idea to insert the batteries during mounting so that you have a rough idea how much clearance is required so that it will not affect the plunger. Here you can see that I needed to mount the battery holder at an angle so as not to block the tube/plunger.

Yellow: Battery Holders
Forward area uses a 2x AA but mounted at an angle. You cannot mount it to sit flush with the shell but push the bottom out slightly as there is enough space from the upper shell. The remaining 1x AA holder is at the grip area. It can sit flush but you will need to remove the lower plastic tab first, as shown by the red arrow.

Green: Micro switches
The micro switch (for the Laser Pointer) under the trigger is connected to be NO so that when the trigger is pulled back slightly, it will complete the circuit. There is no mounting for this switch and so, you need to use ether epoxy or hot melt glue to mount it. I used hot melt glue and built the mounting layer by layer. The second micro switch (for the Muzzle Flash) is smaller and is located at the upper area of the trigger. This will be connected as NC, like a normal switch. Test play with the trigger to see where the ‘trigger’ points are for both micro switches before you mount them. The theory is, when you pull the trigger slightly, the Laser Pointer will be activated. Once you fully pull the trigger to launch the dart, the muzzle will flash.

 

 

 

 

 

 

 

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