The SOT is for the Adjustment of the "dead band" Depending on the usage of this circuit. Dead band is a feedback loop for sampling and making the "return" state a bit less. I asked for this because I didnt want to "osciallate" the circuit at the trigger point. I think Eric determined that a .2v deadband was all I was going to get out of this circuit. But that is good enough since that represents a few psi on the MAP sensor.
BTW, I have tested the circuit, got all of the Gerber files, and am close to get proto's made. If your interested, LMK. It can work an any MAP sensor, and all GM 3 bar and 2 bar sensors. Or any 0-5v sensors. There all real linear.
For me, 10psi = 4V and 17psi = 4.8v...so a high precision 10 turn pot is really needed. My test uses two full 360 degree rotations for only .8v range. Pretty cool~!
Stu