Introduction: Xbox 360 Rapid Fire Modification

A while ago I was asked by a friend to make a rapid fire modification for his Xbox 360 controller. At first, I was not quite sure how to make one , but I agreed to do it. Like always, the internet is the first place I go to when I don't know something. But after a couple hours of searching, I was unable to settle down on a good reliable way to do the modification, so I improvised and created a circuit that actually turned out to work quite well.

This modification works on a Xbox 360 controller, but it can(should) also work on other kinds of controllers.

The white controller was the controller that I made the modification on but since I have finished the modification already, I will be performing the modification on another(black) controller.

Edit: **There has been a change in parts. Look under Step 1 & 6**

Step 1: Materials

- TLC555 timer
- 100k Ω resistor x 2
- 1M Ω variable resistor
- 0.1 μF capacitor
- 0.01 μF capacitor
- micro momentary switch x 2

- Xbox 360 controller
- circuit board

For the 555 timer, make sure to use TLC555, not NE555. NE555 requires a higher supply voltage(4.5v), while the TLC555 requires much less(2v). Because a regular Xbox 360 controller uses 2 AA batteries (3v), a NE555 timer will not operate properly. 

**Edit**: It seems that the 1M ohm variable resistor is hard to find for most people. If that is the case, here is a new parts list:

- TLC555 timer
- 10k Ω resistor
- 22k Ω resistor
- 100k Ω variable resistor
- 1 μF capacitor
- 0.01 μF capacitor
- micro momentary switch x 2

- Xbox 360 controller
- circuit board

Step 2: Find Your Spot

Mark where you want your rapid fire triggers to be. Make sure they are in areas where they will not interfere with moving parts and that the switches would actually fit in those spots. This could really be done at anytime. I chose the spots where the middle fingers rest. 

Step 3: Modify Screwdriver Tip

If you had tried to disassemble the controller already, you've probably notice that the screws on them are security screws. They are not regular Torx  screws, they have a pin in the middle. If you have a Security Torx screwdriver bit that fits, you can skip this step. In my case, I did not have a security screwdriver bit that fits, so I had to modify a regular Torx.

First, I found a regular torx bit that was the right size for the screws. I then used my Dremel tool with some diamond etching bits to grind a hole into the middle of the bit. It sounds simple but you have to be very steady with your hands.

Step 4: Disassembly

Disassemble the controller. There should be seven screws in total, six on the outside, one under a bar-code sticker in the battery compartment. Separate the circuit board from the rest of the controller.

Step 5: Notes on Triggers

After removing the circuit board from the controller, you will notice that the triggers are actually variable resistors. Using a multimeter, find the functions of the pins(which pin goes high when the triggers are depressed). I found that the top-most pin is normally at 1.5v, the bottom-most pin is connected to ground, and the pin in between goes HIGH when the trigger is depressed, which I will call TRIGGER.

Step 6: The Circuit

Here is the circuit's schematic for this project. The pin next to the circle at the bottom left of the chip is pin 1. The end of R3 marked with N.C. is not connected to anything. Vcc rail will be connected to the positive power of the controller, and Ground will be to the negative. TRIGGER button(s) are the momentary switches that will be connected between pin 3 of TLC555 and the TRIGGER pins of the controller.

How it works:
The circuit is a basic 555 astable circuit. It sends continuous pulses of signals(series of highs & lows) through pin 3 at a set frequency. Its frequency is set by the resistors and the capacitors. The 1M Ω variable resistor is used to adjust the frequency. When a trigger of the Xbox 360 controller is pressed, the TRIGGER goes high. Pin 3 of the 555 timer is hence connected to the TRIGGERS, because the series of pulses mimic the signal the controller receives when the triggers are pressed multiple times. This can be very beneficial in First-person shooting games because the frequency of the pulses sent from the circuit can be set far beyond the capability of a human finger.

**Edit**: It seems that the 1M ohm variable resistor is hard to find for most people. If that is the case, use a 10k for R1, 22k for R2, 100k for R3, and 1μF for C1.

Step 7: Building the Circuit

For this modification, the on-board components are the 555 timer, the two 100k Ω resistors, and the two capacitors. The 1M Ω variable resistor and the two momentary switches will be connected off-board. 

Start by laying out the on-board parts on the circuit board first; try using minimal amount of board. Space is a constraint. 

Step 8: Building the Circuit

Solder the TLC555 on the board first. It is not necessary to put solder on every single pin. For me, I only soldered pin 4 and 8.

Step 9: Building the Circuit

Next is the 0.1μF and the 0.01μF capacitor. Take one lead from the 0.01μF capacitor and connect it to one lead of the 0.1μF capacitor. Take the other lead of the 0.01μF capacitor and connect it to pin 5 of TLC555. Leave the connection between the two capacitors and the other lead of the 0.1μF capacitor alone for now.

Step 10: Building the Circuit

Add the two 100k Ω resistors. One will be connected between pin 7 and pin 8; the other will have one of its leads connected to pin 2, pin 6, and the lead of the 0.1μF capacitor that was left untouched in the previous step, and the other lead of it left alone for now.

Step 11: Building the Circuit

The on-board components should all be in their designated places now, but there are two more connections to be made between them. The first one is between pin 4 and pin 8. Second is between pin 1 and the connection between the two capacitors.

Step 12: Holes for Buttons

Cut out the necessary holes. I did not mention before to mark a spot for the 1M Ω resistor, because it doesn't have to be at a precise spot nor is it even necessary to make a hole for it. I do, however, recommend drilling out a hole for it because that makes it much easier to adjust; it can be anywhere, as long as the variable resistor does not interfere with other things in that area. 

I used a 1/4" drill bit for the 1M Ω variable resistor and 3/16" for the buttons, both brad pointed. Brad point bits are desired because they give higher precision when drilling, they don't tend to wander and they also create much cleaner holes. For even better precision, I used pilot holes; they were made by melting the plastic with a hot metal pin. A 3/16" drill bit was used to drill out the holes for the buttons even though 1/4" is the perfect size because it is very easy to take away too much material from the plastic of the controller. The holes for the buttons were drilled and filed to fit the momentary switches snugly. 

Step 13: Trigger Buttons

Now it's time to connect the momentary switches. Because only two of the four leads on each button will be used, to start off, I broke off two leads from each button that are not going to be used. If you decide to do so too, please make sure the remaining leads are the ones that have their leads normally opened, and closed only when the button is depressed. Next, connect two wires to pin 3 of TLC555. Connect those wires to the momentary switches, one wire to each. Attach a second wire to the lead that is not connected on each of the buttons. Use heat shrink tubes to protect connections. Then connect the second wires on the buttons to the TRIGGERs on the controller. One to the left TRIGGER and the other to the right TRIGGER. 

Step 14: Variable Resistor and Power

The variable resistor will be connected between pin 7 and the lead of the 100k Ω resistor that is not connected to anything. Since the variable resistor has three pins, I numbered them to make things easier to understand. Only pin 2 and pin 3 of the variable resistor will be used. One will be connected to pin 7 of TLC555 and the other will be connected to the 100k Ω resistor. It does not matter which goes to which. 

Next, attach a red wire to pin 8 and a black wire to pin 1 of  TLC555. These will supply power to the whole circuit. Connect the other end of the red wire to positive power of the controller and the black to the negative. 

Step 15: Reassembly

Now that the circuit is completed, reassemble the controller. You are most likely only be able to fit one of the vibrator motors back into the controller. I chose to put the one with the larger mass on its drive-shaft back in and leave out the one with the smaller mass. Use hot glue to attach the buttons and the variable resistor. After gluing everything in, make sure they do not interfere with other moving parts and that everything fits back in the controller. The spots that I chose to put my buttons are right next to the levers connected to the triggers; if too much glue is used, it would interfere with those levers. 

Step 16: Usage and Adjustments

First, make sure that the controller actually works. Put in two AA batteries and turn on your Xbox 360. Make sure that all original buttons and joysticks work. Press on the new rapid-fire buttons. They should work like the original triggers(except that holding them down will rapidly trigger). They are most likely going to need  adjustments to work at their best. For adjustments, start by turning the variable resistor all the way counter-clockwise with a flat head screwdriver. Then, turn it clockwise about half-way. Turn it a little each time, barely moving, clockwise or counter-clockwise to gauge in to the perfect rate of triggering. 

Step 17: Thanks for Reading

Well, that's it. Questions or comments? Please post below.

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