1. In order to half the amplitude of the signal, you would have to use a voltage divider. By putting two resistors in series connected to ground and taking the output between the two resistors.
2.Capacitors changed the signal pattern by acting as filters. When you put a capacitor in series with the circuit, it acts as a high-pass filter, killing the low frequencies. When you hook it up as a bypass to ground, it acts as a low-pass filter, killing the high frequencies. When you use different values of capacitors, it will have an effect on the cutoff frequency. For example, when you are creating a high-pass filter, a higher value of capacitor will bring the cutoff frequency down.
3.The diode drastically affects the timbre of the sound by adding quite a bit of distortion. To put it into the circuit, I simply replaced the capacitors with the diodes.
1. I would like to further discuss my second idea from last week, the photoresistor-controlled onboard guitar effect. Ideally, this would work in any ambient light situation, so in reality would use proximity sensors instead of photocells. The final product would be inset into the pick-guard with cells about the size of a finger (1/2" radius). I would have a few effects, filters, distortion, etc. that would have their controls manipulated by the sensors on the guitar. Most interesting would be to have a pitch bend or vibrato connected. Ideally, you would be able to switch between the different effects you are controlling easily on the guitar. With this, you can use a finger or two to control the effects and still play with your thumb and leftover fingers. The added expression from the effects makes up for the lack of notes available to play due to the lack of fingers available to pluck the strings.
2. Realistically, I will probably have to end up using photocells as proximity sensors are very expensive. To get around this, I could calibrate it so that sensitivity is low and when the cells are picking up the most light, the effect parameters are all the way at zero, so they aren't fluctuating full-out otherwise. Also, it would be very difficult and time-consuming to create a switching system that would allow you to control many different effects and aspects, this would probably require digital to be truly efficient. I will probably end up settling with one or two filters and manipulating two things on each. The easiest way to hook it up would to have the effects not on the guitar, but on a separate box. I can put together a guitar cable and the other wires necessary into a single cable and run it all through the input jack area on the guitar (using 1/4'' and multi-pin plugs). It would be easiest to take professional pedals and simply hotwire the pots to my photocells, but I will probably end up building my own to see how small I can get them to have the possibility of putting them on the guitar itself. Also, otherwise, the project seems a little too simple.