Improve Basic Electronic Trigger Circuit

I have a basic electronic circuit design to trigger a LOW-HIGH-LOW signal from a PIR device. The trigger is not enough to to activate the required integrated chip. The circuit is standard, I need the correct component values to ensure the trigger is high enough to activate the chip. Circuit power is 3.3v (not 5v) (PIR runs fine on 3.3v)
NOTE: I have a several recommendations of "guessing" which haven't worked, looking for an answer based on best practice.
Thanks