Guitar Hero Modification Help

[xtraman122]

Hi, I'm new to these forums and electronics in general with only a basic understanding of some simple circuits. I've been following a diagram from a Guitar Hero forum but ran in to some problems and couldn't seem to get any help. The main point of the circuit is to create a square wave mimmicking a potentiometer on the whammy bar on the guitar going from high to low. The 10k pot in the diagram is to change the frequency of the wave. My main problem is figuring out how to go from the dran up diagram to how it should be laid out on a piece breadboard, and which 2 leads on the pot I'm supposed to use. So if anybody could draw out how it would be laid out on breadboard or make a diagram in Eagle so I could make the board using the inkjet method I would be forever debted to you.

Thanks in advance for any help,
-Pete

 

[dknguyen]

All pots are really variable resistor dividers. Usually, the two outter pins are the ends of the divider and the middle pin is the wiper that goes up and down. To use it as a variable resistor, you only need one resistor in the variable resistive divider- you pick any one of the outer two pins and use the middle wiper pin, completely ignoring the other end pin.

It takes a lot of work to lay out a PCB- something that no one is going to do for you unless they're paid a heft sum. Best just to download the software and learn to use it yourself. ANd on a breadboard? Well, stick the parts on a breadboard and wire them together...there's way more than one way to do it and everyone does it differently, just like laying out a PCB.

 

[kchriste]

Your diagram is almost a pictorial itself! There is an error in that diagram and the 555 won't oscillate. I've fixed it. Just lay it out something like this x-ray view from the top:

 

[xtraman122]

I figured laying out the PCB would be a pretty big job, wasn't sure if it was just me being bad with the program. I was a little confused on how certain things should be wired on a piece of board as opposed to just drawn up. That wire switch makes me confused because the person who made the diagram had it wired with the schematic I posted and it worked fine(he had a video fo it).
Thanks for the help
-Pete

 

[kchriste]

The way it was wired would have caused the output of the 555 to pulse once when the switch was pressed and then do nothing until the switch was turned off and on again.

 

[davidbball13]

why is the switch on the positive when i do a 555 and need a switch i do a switch between pin one and ground...... just a thought

 

[xtraman122]

I don't know. I didn't make the schematic, a person from ScoreHero did.

 

[kchriste]

why is the switch on the positive when i do a 555 and need a switch i do a switch between pin one and ground...... just a thought

Switching the positive lead of the battery is the "normal" way of doing it. You can be unconventional and switch the negative lead of the battery. It's up to you. It'll work just the same in this case. I wouldn't recommend putting a switch on pin 1 of the 555 though.