Adjustable Current Source – 0 to 1A

This voltage-to-current (V-I) converter delivers a well-regulated current to a load. The circuit accepts an adjustable input voltage from Trimmer potentiometer PR1 and converts it to an output current from  0A to 1A. The current is regulated by feeding the voltage across a low-side, current-sense resistor R9 back to the OPAMP. The output Darlington pair allows for higher current gain. Feedback components R8 and C6 provide frequency compensation to ensure the stability of the circuit during transients. They also help reduce noise. R8 provides a DC feedback path directly at the current setting resistor, R9, and C1 provide a high-frequency feedback path that bypasses the NPN pair.