Hello,
here i have the problem with same circuit
LM317 / LM338 / LM350 CURRENT REGULATOR CALCULATOR | Circuit Project Electronic
I need to adjust in the range of 1mA to 500mA with the precise of 1mA difference.
The output voltage should be 12V.
- Am trying to adjsut with 10 K digital potentiometer near 10 ohms resistor
- the precise current must 1mA difference
Please suggest any ideas or theoritical expressions for the circuit.
Best Regards.
The circuit you linked is not a
Current Regulator circuit, it is a
Voltage Regulator circuit. There is a big difference between the two.
In a voltage regulator, you turn a pot to adjust the output voltage E, and the impedance of the load R (what the supply is connected to) determines what the current I is (Ohms Law: I=E/R, the supply sets E, R determines the current I).
In a current regulator, you turn a pot to adjust the output current I, and the impedance of the loadR (what the supply is connected to) determines what the voltage is (Ohms Law: E=IR, the supply sets I, R determines the voltage).
I think you need a pot adjustable current regulator that starts with an unregulated input voltage of 12Vdc (wall-wart plug-in power supply or battery?), creates an adjustable constant-currentbetween 1mA and 500mA with a resolution of 1mA. Such a regulator would put out nearly 12V if the output is left open.
If set to 500mA , this regulator could keep the current constant as the load resistance varies from 0 Ohms (a short) up to R=12/0.5= 24 Ohms.
The circuit in post#9 is how a theoretical current regulator would work. Make the sense resistor 2 Ohms instead of 1. The control voltage source can be replaced with a reference voltage and a digital pot.