I have this circuit. The goal is that it going to control the current loop by using the NPN-transistor. My problem here is that 0V results that the output from the Op-amp is near 24V. Why?
If I'm increasing the voltage a little bit, then I got this.
And even better, If I implement a schottky diode, then I got this.
So why does the output goes to near 24V when the non inverting input is 0V?