Now look at the "mix-out" 50K pot. It is  connected from the op-amp output to the stick pot output. If the mix-out pot is in its center position we will always get 2.5 volts out. Why? because when the stick is centered 2.5 volts is applied to both end of the 50k pot, and the average of 2.5 volts is 2.5 volts. Now as we move the stick to the minus side, lets say to 2.0 volts, the inverted output of the op-amp goes equally as much to the plus side, 3.0 volts, or vice versa. The average of the 2.0 volts on the low side and the 3.0 volts on the high side, would still be 2.5 volts at the center of the mix-out pot.

The amount of mix, and the direction of mix, is then determined by moving the mix pot off center in one direction or the other. This mix output would then be applied to mix-in on another channel (like aileron to rudder if you wanted your rudder to move when you moved your ailerons). Mix in is

shown in Figure 8 on the Stick pot input leg to the op-amp.

Mode I vs Mode II - What is a Mode I and Mode II radio and why do we have them?

Well the answer goes back to the days of reed radios. In a reed radio you did not have a 2 axis stick or fully proportional channels.

Each control had its own self centering switch which you manually pulsed to operate the control. Your two primary switches were rudder (or aileron) on the right side of the transmitter (right hand thumb operated), and elevator on the left side of the transmitter (left hand thumb operated).

Looking at the right switch it moved horizontally. When you moved the switch to the left, the servo went to full left and stayed there. When you