Can anyone out there tell how to reduce voltage in a DC circuit without also reducing the amperage.

Thanks

 

The goal is to keep the current the same, regardless of what the voltage is.

That is normally called a "constant current circuit" or "constant current driver".

A google search (or search this forum) would give a lot of examples.

Normally it is done very simply with two transistors and some resistors, or with a transistor, some diodes and resistors.