Diagram Plus guide

This is the simple 1-Ma Current Sink Circuit Diagram. A fixed current flows through any load that is connected between the positive supply and Ql`s collector. The non inverting terminal of the op amp is grounded, and negative feedback flows between the output of the circuit (Ql`s emitter) and the inverting terminal. The voltage across Rl is thus equal to the voltage at the inverting terminal (approximately 0.55 V), so a fixed current of about 1 mA flows through the load, Ql`s emitter, and Rl.