I think the device you need is a DC-to-DC converter. Any with a maximum input voltage of 72V or more, an output voltage of 5V and an output current over, say, 200mA. DigiKey.com has a bunch to choose from starting at about $12.
I think the device you need is a DC-to-DC converter. Any with a maximum input voltage of 72V or more, an output voltage of 5V and an output current over, say, 200mA. DigiKey.com has a bunch to choose from starting at about $12.