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Help with Controller Mod. Help with circuit

I recently started to play a game on my xbox. It requires me to pull the left trigger very very fast. The trigger is ran off a potentiometer.  The controller "fires" at a certain point. I need to make a circuit that can do a pretend pull repeadatly. So it has to be an ajustable voltage that can repeadtly go when I press a button for a couple seconds. So it can be sometime of resonator or something. I am not sure how I could make something that fire the potentiometer to fake a couple "fires". I will get more information later when i open up the controller. IF anyone has question i can try to explain more.





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I kind of understand the 555 timer but i am not sure how i will set the the output voltage pulse. I think this might work but just incase I have another idea. There is a specific voltage that the chip reads from the potietiometer. It is .45 -.49 v if i can recreate this it will always keep firing. what i had in mind was a pos supply running to a momentary switch then to a potentiometer that i can set at .45 -.49 volts.
 I cant seem the figure out what the input voltage is. the highest the voltage goes is about 1.09. so i am going to link two potentiometers together and have the one set so its output is always .45-.49 and just press a button and trick out the chip. Anyone know if this will work or not ?

I was picturing a 555 timer than had an adjustable RC circuit and a button that would only turn the circuit on when it wass pressed and then reset it when it was not pressed. I also would need to be able to dial in the right voltache with another variable resistor because we are tricking out a potentiometer on a game controller. So if anyone could help me design a circuit like this i would love you guys.


Thanks dencohe 

Check out http://www.uoguelph.ca/~antoon/gadgets/555/555.html for a lot of info on the 555 timer. There is a circuit on that page, which is described as a 555 tester. Start with that as a basis, eventually leaving out R3+R4+the two leds. Use them in the beginning to check if your circuit is working. In the bottom there are some example circuits. If you want faster/slower pulses, google for "555 calculator". Hope it helps. If not, feel free to ask again

Hmm. Maybe you want to look at a digital potentiometer, like the AD5220. It acts just like a regular potentiometer, except you can "dial it up" or "dial it down" by setting I/O lines high or low. One line tells it whether to go up or down -- high means increment, low means decrement -- and another line acts like a trigger -- for every pulse it sees on that line, it increments (or decrements) one step (out of 127, I think). So to go from zero resistance to full resistance, assuming you had the up/down line wired to I/O pin 1 and the clock (trigger) line wired to I/O pin 2, you'd do something like:


#set up/down line high


#send 127 pulses on clock line

for i = 1 to 127

   HIGH 2

   LOW 2



Just an idea.


think he is looking for something like all in one ic, to put incide of the remote controle, and close it, to look like a normal controler, but moded..