The next figure shows a simplified diagram of the Tracker’s core circuit. The sine wave generator is the test signal source and is connected to a resistor voltage divider made up of Rs and RL. The load impedance, RL, is the impedance of the component under test. RL is in series with the Tracker 2800's internal or source impedance Rs. Because Rs is constant, both the voltage across the component under test and the current through it is a sole function of RL.