between pins 6 and 7 of IC1A. The most important thing to understand here is that, the
more resistance between pins 6 and 7, the more output IC1A will produce. The less
resistance between pins 6 and 7, the less output IC1A will produce.
Now let's bring the functions of the LDR and the op amp together.
We know that when the LDR is in an at rest state , it is at maximum resistance. So when
no voltage is being applied to the LED portion of the opto-coupler, and thus no light is
being applied to the LDR, this means that the op amp is amplifying the guitar signal to the
circuit's fullest potential. And when a voltage is applied to the LED portion of the
opto-coupler, and thus applying light to the LDR, this means that the op amp is not
amplifying the guitar signal to it's fullest potential, and perhaps even diminishing it.
So what we can assume at this point is this: The more voltage applied to the LED portion
of the opto-coupler, the less signal output we get. And the less voltage applied to the
LED portion of the opto-coupler, the more signal output we get.
So what controls the voltage that is applied to the LED portion of the opto-coupler? The
envelope trigger.
This circuit actually has two envelope triggers or envelope followers that work in parallel.
The second trigger is preceeded by IC1B, so it does not receive the same amount of signal
as the first. Having two triggers in parallel helps to smooth out the compression, and
having two triggers with uneven input signals adjusts the taper of the transistion. None
the less, the two transistor based envelope triggers are identical and the way they work is
very simple. You can better understand the relationship between the envelope triggers
and the LED portion of the opto-coupler better by looking at the LED status light and
R11 on the schematic.
The cathode of the LED status light is connected to +V. R11 is connected to ground on
one end when the footswitch is in an engaged state, and the other end is connected to
the anode of the LED status light R11 is there to make sure the LED doesn't get too
much current and burn out. But if you increase the resistance of R11, the LED status light
will get dimmer. And if you decrease the resistance of R11, the LED status light will get
brighter.
Like op amps, transistors can be used for many different things. But in this case, they are
acting as variable resistors. The LED of the opto-coupler and the transistors in the
envelope triggers are basically do the same thing here as R11 and the LED status light.
The cathode of the LED is connected directly to +V. The anode is connected to the
collectors of the two transistors(if we ignore R10 and C6). The emitters of the transistors
are connected to ground. When an input signal is applied to the base of the transistors,
the resistance between their collectors and emitters decreases and the LED becomes
brighter.
So....
1. The harder you strum the guitar, the stronger the signal being applied to the base of the