Take a resistor and LED, connect them together with one end at the voltage source, let’s say 5v. Leave the other end disconnected. Let’s assume the voltage drop from the LED is 3v, which is about right for some blue and white LEDs. Standard color LEDs like green red and yellow are about 1.5v, but you’ll see that still can cause a problem in a sec.
Take your multimeter and measure the voltage at the resistor on the side opposite the power source. There’s no current flowing, so there is no voltage drop across the resistor, so the voltage between the resistor and LED is 5v, same as the power source. Now check the voltage at the other end of the LED. Even though there is no current flowing, the fact its a diode means that there is a drop in voltage, in this example 3v. So the voltage at the far leg is 2v. You can check this with a multimeter.
Now, the signal lines of the pcb’s are connected to inputs of logic gates. Those inputs check the voltage at the signal line to determine if they’re high or low. You just connected a wire to it that is at 2v, even with no current flowing through it, when the input is expecting around 5v when not pressed. I hope you can see why some inputs may treat that as meaning the button is pressed. Sure, the LED won’t light up, but the stick won’t be very usable on a console.
There are different ways the inputs can be made on the pcb, which is why it will work on some pcb’s just fine, and not on others. So, go ahead and try it out with the pcb(s) you’re planning on using, but it’s not as bulletproof as using the inverter.
I’ve been almost intentionally neglecting to mention that the inverter acts as a choke of some sort. The pins on the 74HCT04 and 74ACT04 can source at most about 25mA of current, so even if there isn’t a resistor, 25mA is all that can be gotten. This helps protect things so too much current doesn’t get pulled, a protection that isn’t there by wiring it directly.
Are you sure about your explanations Toodles ?
Between +5V and ground, there are the LED and resistor in series (in the case where the button is depressed). Assuming current flows in this “branch”, the voltage across the LED would be around 3V and the resistor would take the rest (=2 V). So according to me, the PCB would detect a 0V at the signal side. Please correct me if I’m wrong (electricity is not my subject) but that’s how I see things…
If your explanation assumes the button is pressed, then yes, your description is 100% accurate. The 0 voltage at the signal would indeed be seen as a button press, and everything works as it should.
I thought that a pull-up resistor inside the PCB would bring the voltage of the signal pin back to Vcc internally (?).
Since both pins of the LEDs are connected to Vcc when the button is not pressed, the pcb shouldn’t detect a button press.
That’s how I understand it anyway.
The reference you take is a comment from TingBoy. He said there that he’s using no resistor. If the led resistor has an additional pull-up task (which I don’t know at this point because the led diode is in series), then this could explain why it don’t work on his PS2 (?) PCB?
speedsterharry :
Same way I understood it. I’ve made so far two sticks with this wiring, both xbox360 mad catz and no problems or odd behaviour so far
But using the inverter includes an additional choke, that’s a nice feature.
Like I said before: Yes this is not a stick, this a 2 player panel for my built-from scratch cab. The cab in itself is functional but there are areas that need some more work, mainly decorative. I will post some photos in another thread when the project’s over. Will add comments in due time.
I have exactly the same point of view regarding Tingboy’s findings. Glad I’m not the only one
+1 for CMOS chip protecting the diodes “downward” (don’t know what’s the right word)
hey i am wanting to implement this with Toodles Cthulhu PC/PS3 Board, and i spoke to toodles about this and has recommended i speak to kaytrim having only posted a few times i cannot pm you directly, would it be possible to build a custom mod to allow me to have leds working in 12 button layout also having the stick to activate when a direction is pressed,
i am a noob on the forum and have a ruff idea on what i wanted to build, is it possible for you (kaytrim to design something that would require the minimum of soldering on my behalf) but ready to be implemented with toodles board.
as i am not experienced with electronics but with clear instructions i may be able to get one going, but i do not even understand the diagrams.
You can’t PM? Is that one of the new SRK rules? I thought new members were only restricted from the trading forums until certain requirements are met.
Anyways, Kaytrim isn’t the OP of this thread, but he does chime in every now and then. AFAIK, he’s the only person on these forums that sells the mod as a kit. Perhaps you can make a deal with him via email or something
For all you XB360 modders or whomever wants a custom Arcade Stick with lights.
I updated the schematic to be complete and has 11 buttons which is more than you could possibly need. I didn’t put in the
joystick because I figured it was elementary enough. I did include an LED for the joystick if you so wish.
I also changed the resistance to be a little more forgiving for a brighter light and upped the watt rating just to be safe. The
resistance is much lower for the reasons stated above and because of the diodes I use to regulate the current before the
resistor. They have a small voltage drop of about 0.7V that drops the voltage to about 4.3V. So the resistance needs to be less
to account for this.
This image helps if you want to do a perf board because it illustrates an approximate association space wise. All you have
to do is jump a wire where you see the half circles and where the wires cross or intersect they are connected.
I also saw that some people were talking about uneven light distribution and I added a little explanation of how to kinda fix it.
If you put two LEDs in the button on either side of the switch it will mostly help. All you have to do is connect them in parallel
to each other and lower the resistance to 27 Ohms. The image illustrates this.
Ill post a schematic of what the perf board I intend to build will look like as well as pictures as soon as I do it.
I also intend to write a complete instructible or something on all the steps necessary to create a custom Arcade Stick from
scratch for use with an xbox 360 including the light mod since the controls for SSF2THDR are so horrendous and by
association I assume the ones for SFIV will be as well.
I can’t do any examples yet because I am still waiting on some components to come in the mail. What I will do though is when
I get them I am going to solder up a complete perf board with the lights attached to it so I can demonstrate the way I have
it set up and will organize it.
I think thats it.
Just send me a message if you have any questions or comments.
There is only one switch and it is used used to change the Light mode.
The buttons are wired exactly the same as TingBoy’s, there are just more.
The particular switch I am using is called a Double-Pole Double-Throw Center Off switch it has six prongs and only four are connected at a time or none are connected. Ill illustrate.
The top left prong is connected to the power for the Hex inverter.
The top middle prong is connected to the power source.
The top right prong is connected to the LEDs.
The bottom left prong is connected to the ground coming from the Hex inverter.
The bottom middle prong is connected to the ground.
The bottom right prong isnt connected to anything.
The Middle picture illustrates the “off” position where the lights are completely off. Nothing is connected so no power flows through the HEX inverter or LEDs.
This Left picture illustrates the Light on Press or Right position. In this position the Top Left-Top Middle prongs are connected and the Bottom Left-Bottom Middle prongs are connected.
What this does is send power to the hex inverters and connects them to ground. So the Light on Press works like in the other diagrams. The signal from the inverter passes through a diode before it gets to the resistor and then the LED because if it didnt then there might be a problem of reverse overload when the Light Always On mode was enabled.
The right picture illustrates the Lights Always On or Left position. In this position the Top Right-Top Middle prongs are connected and the Bottom Right-Bottom Middle prongs are connected.
What this does is routes power to the button LEDs. The power is cut off from the HEX inverters and so is the ground so current can’t flow that way, the current has to go strait to the LEDs. It has to pass through a diode and then a resistor to get there because if it didn’t then when the hex inverters were enabled all the LEDs would be connected together and all the buttons would light up when one was pressed.
coolm thanks for the quick answer. Much clearer now! This switch and the idea of connecting could also help to change colors with with built-in RGB leds. When using common anode RGB LEDs it possible to switch between specific color cathodes to GND. Just an idea… thumbsup keep me informed about the project!
This is what I intend the perf board to look like. I designed it on a grid and I tried to design it so that I wouldn’t
have any wires crossing on the same side as each other. The Dark Red lines are wires on the bottom and the Dark
Green lines are wires on the top.
The row of 24 rectangles are the diodes for regulating current, the row of 12 rectangles are the resistors, and the big rectangles are the connectors for ribbon cables I intend to use.
I did this trying to cut down on the invariable mess that would arise from just soldering wires all over the place as well as trying to add ribbon cable connectors to make attaching the other parts more organized and neater looking. The way I have designed it it wouldn’t be much more work to making and actual PCB.
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