Recreating the circuit that just vanished.... Here, a Zener diode allows one to detach the OpAmp output voltage level from zero. Like this, an opamp which cannot swing the output rail-to-rail can be used for current control. Flip the switch near Zener to see its effect.
In reply to the comment on vanished circuit: The purpose of this circuit is to measure the current in the load (100 Ohm on the right) by using a shunt resistor (1 Ohm on the right). The small voltage on the shunt is amplified to a level of about 1.2 V. The reference voltage on the inverting input can be adjusted with a pot. The 18 V source is assumed regulated, while the 38 V can be obtained from 18 V by a cheap DC-DC converter such as XL6009. Basically, this circuit should be inserted in the control FB loop of this DC-DC converter, with the 1.2 V output connected to the FB input of XL6009, for example. Like this, this circuit will be able to maintain a fixed current in the load.
