Installed and tested the air mixing system today. The servo that controls the air mixture jumped and did not seem to work properly. I changed the servo to a new one and this one just oscillated between two extreme angels. So I wet and got my big box with capacitors and began to try them on the circuit. After a while I found a capacitor that seemed to work. When I connected it, the servo stopped oscillating and when I moved the knob, the servo moved precise.
The controlling circuit consists of three parts. The first one is a comparator that compares the voltage from the lambda censor and tells if itís too high or too low. It has two potentiometers that you can set the high and low voltage value with. The second part is a counter and resistor that increases or decreases a resistance when it gets a signal from the comparator. It has two potentiometers to set how fast it should change the resistance, one in each direction.
The resistance is a value for the third part, which is the RC controlling circuit. It takes the resistance value and makes it into a pulse code that the servo understands. It also contains a power supply that makes 5 V for the servo.
I have drilled holes in the big control panel for buttons and gauges. Before I install them permanently, the panel is going to be painted black.