The pipe forms with the jet a feedback loop. This is an instance of a positive feedback loop. This is an example of a negative feedback loop. This is an example of a positive feedback loop. Barkhausen's criterion applies to linear circuits with a feedback loop. Instability is thus avoided without modifying the feedback loop. It serves as part of a negative feedback loop in signal transduction. Noise shaping works by putting the quantization error in a feedback loop. This provides a good example of a negative feedback loop. CDC25 resulting in a positive feedback loop. The linearity is improved by using a second optocoupler within a feedback loop. The cycle then repeats in a negative feedback loop. The CLOCK-BMAL dimer acts as a positive limb of a feedback loop. Ca activate PLA2, AA and cPKC creating a positive feedback loop. With this feedback loop the player can create a continuous string vibration.