Joystick 2 button mod questions

[idrougge]

I'm no electronics expert either, but I surmise that there are online calculators for the correct resistor value.

[xArtx]

470R would be a good start.

[DesktopDynamite]

Originally Posted by xArtx

470R would be a good start.

Yes or 360r

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[Daedalus]

As a rule of thumb, I always use either 330 or 470 ohm resistors on LEDs driven by 5V, depending on the type of LED - low current types (e.g. red) get a 470, higher current types (e.g. white or high brightness red) get a 330.

However, to properly calculate the resistor required, you need to know the forward voltage drop across the LED. The resistor value is then calculated from the remaining voltage and the desired current using Ohm's Law. Your LEDs are rated for 20mA, but that's probably a maximum, and you would usually not run them quite that high. A typical forward voltage drop is 2.2V, so that leaves 2.8V to drop across the resistor. To run 10mA through the LED, your resistance is 2.8/0.01, which is 280 ohms. For this I would pick a 330 ohm resistor as the next commonly available value.

You can easily adjust this based on your actual requirements once you know them, for example if you really do want 20mA, and your LEDs have a drop of 2.4V, the calculation is adjusted for 2.6V/0.02A, which is 130 ohms. 150 is the nearest higher common value (though you can get 130 if you search for them). Hope that makes sense!

[Juz400]

Back in the day I modded my competion pro for a second fire button, was just a case of replacing the lead with one from a mouse that had more wires inside it.
It also worked on a MSX (nemesis 1 and 2 ftw!)

To give your Idea a more profesional look, why not just get a 9 pin serial lead and lop of the end you dont need, then check the pin out with the wires with multimeter beep test so you got your connections right.

http://www.ebay.com/itm/Durable-DB9-...AAAOSwXeJYLWjF

Only problem I found was you are holding the joystick in your left hand with thumb over the fire button or reversed if you that way. Its quite difficult to hit that second button with any meaning!