This circuit shows how to get 5 V under low current from an operating amplifier 741. I got this circuit in a 1978 English publication making changes to make its assembly feasible even today. The zener diode determines the output voltage and the maximum output current is of the order of a few milliamps. Other operational amplifiers may be employed. The divider formed by the 390 ohm resistor with the 5k6 resistor together with the zener determine the output voltage.
