A modified version of 1 and 2: use a Zener diode in place of one of the resistors to limit the voltage for the regulator and reduce the power consumption under load.

A better solution would be to use a resistor and a low-power Zener Diode co create a 5.7 V reference and an emitter follower with a high-voltage BJT, which are not hard to find.

The 50 mA solutions would be the same, except you'd be wasting (and dissipating) about 12 Watts.

Another solution would be to find or build a switch-mode power supply, of course.

A modified version of 1 and 2: use a Zener diode in place of one of the resistors to limit the voltage for the regulator and reduce the power consumption under load.

A better solution would be to use a resistor and a low-power Zener diode co create a 5.7 V reference and an emitter follower with a high-voltage BJT, which are not hard to find.

The 50 mA solutions would be the same, except you'd be wasting (and dissipating) about 12 Watts.

Another solution would be to find or build a switch-mode power supply, of course.

A modified version of 1 and 2: use a Zener diode in place of one of the resistors to limit the voltage for the regulator and reduce the power consumption under load.

The 50 mA solution would be the same, except you'd be wasting (and dissipating) about 12 Watts.

Another solution would be to find or build a switch-mode power supply, of course.

A modified version of 1 and 2: use a Zener diode in place of one of the resistors to limit the voltage for the regulator and reduce the power consumption under load.

A better solution would be to use a resistor and a low-power Zener Diode co create a 5.7 V reference and an emitter follower with a high-voltage BJT, which are not hard to find.

The 50 mA solutions would be the same, except you'd be wasting (and dissipating) about 12 Watts.

Another solution would be to find or build a switch-mode power supply, of course.