Controlling Voltage and Current

[Plmrguest]

I am trying to control voltage range from 1.5 to 34 V using LM338 voltage regulator with 1000u capacitor at the input 430u capacitor ; at the output with potentiometer @ the adjustment terminal.

I have 37v and around 5 Amps current at the Vout but when i try to reduce the voltage using potentiometer,resistor 120 ohms burns out. Please suggest me how to control and get constant Voltage & Current.

[Relayer]

[quote]Please suggest me how to control and get constant Voltage & Current.[/quote]
[b]Hello Plmrguest,
Can you please put up a picture of [u]YOUR[/u] schematic and how you wired it up.
Regards,
Relayer[/b]

[bwetman]

Hello,
Using voltage regulating device like (BJT & FET) we can control the voltage and current.

[pebe]

[quote="Plmrguest"]I am trying to control voltage range from 1.5 to 34 V using LM338 voltage regulator with 1000u capacitor at the input 430u capacitor ; at the output with potentiometer @ the adjustment terminal.

I have 37v and around 5 Amps current at the Vout but when i try to reduce the voltage using potentiometer,resistor 120 ohms burns out. Please suggest me how to control and get constant Voltage & Current.[/quote]
Forget the LM338 series regulator. What you need is a switched mode buck converter like this one. It's easier to use and much more efficient.
http://www.ebay.co.uk/itm/DC-Buck-Step- ... XQ3kNTgqYl