Peter Stein
New Member
I have been trying to use an ebay style LM2596 module to scale the input voltage rather than regulate to a fixed voltage. I have been unable to find a way to do this without adding additional op amps and associated cctry. What I am trying to achieve is a scaled step down converter, with say a 3 to 1 step down, so feeding 30 volts in will result in 10 volts out, 10 volts in would result in 3.333V out etc.
My first thoughts were that should be easy - just remove the pot, and feed a voltage divider (two resistors) connected to input voltage to FB pin on the module. In hindsight that can't work as there is no feedback to maintain that ratio - I need a mechanism to compare the voltage divider output with the LM2596 output and feed a correction to the FB pin. And as far as I can see only extra opamps and or comparator cctry would give me that functionality - has anyone an idea that would avoid that complexity - the output only needs to drive a lamp or motor so super smoothed output not required?
My first thoughts were that should be easy - just remove the pot, and feed a voltage divider (two resistors) connected to input voltage to FB pin on the module. In hindsight that can't work as there is no feedback to maintain that ratio - I need a mechanism to compare the voltage divider output with the LM2596 output and feed a correction to the FB pin. And as far as I can see only extra opamps and or comparator cctry would give me that functionality - has anyone an idea that would avoid that complexity - the output only needs to drive a lamp or motor so super smoothed output not required?