Need help in controlling Voltage and Current

Thread Starter

plmrguest

Joined Nov 20, 2015
2
I am trying to control voltage range from 1.5 to 34 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.
 

crutschow

Joined Mar 14, 2008
24,093
You can get constant voltage or constant current, pick one, you can't control both at the same time.

Post the schematic of what you have.
 

Thread Starter

plmrguest

Joined Nov 20, 2015
2
Here is my schematic for you reference i have both voltage and current , since we can't control both voltage & current
so i need to keep the voltage constant 32V and current should be adjustable.
 

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bertus

Joined Apr 5, 2008
20,228
Hello,

You can never have a higher voltage on the output of the regulator.
There will be a dropout voltage of 1.5 to almost 3 volts depening on the drawn current:

LM338_dropout_voltage.png

Bertus
 

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