Ni-Cd and Ni-MH Adjustable Constant Current Project

Simple Ni-Cd and Ni-MH Adjustable Constant Current Project.This is a battery charger circuit with adjustable current for Ni-MH or Ni-Cd. It can be used for a constant current power, which can be set to any value from a few milliamps to about 500 mA. The maximum current is 500 mA, because that is the limit of transistor BC140. The input voltage must be above 5.25V output voltage, this is due to losses as 1.25V current limit and approximately 4V regulator.

 Battery Charger Ni-Cd and Ni-MH Adjustable constant current Circuit Diagram

The LM317 regulator is used, it should have a sink.

Components
R1 100Ω resistor
VR1 trimpot or potentiometer 500Ω
Capacitor C1 0.1μF
C2 Capacitor 0.01μF
Diode D1 1N4001
Q1 Transistor BC140
IC1 Voltage Regulator LM317