I would like to use a 50A 28v alternator to power a 14v 70amp electrical circuit. Does anyone know if there is a voltage regulator, or voltage converter that might be able to do the job?
Many thanks!

 

You should be able to regulate the alternator voltage to give 14V with the proper regulator, but the current would be limited to 50A due to the winding size.

Is the alternator regulator internal or external?

 

Is this alternator providing AC output or is an automotive type. If AC output, a 2:1 transformer would work.

 

The voltage regulator is external to the alternator.
The 12v power is for an aircraft.
Thanks for responding!

 

The voltage regulator is external to the alternator.
The 12v power is for an aircraft.
Thanks for responding!

I would definitely not recommend you do anything like that for an aircraft. Failure is not an option when you are doing modifications to an aircraft. And I'm sure the FAA would not approve either.