When Multisim simulates a circuit, it first finds the DC operating point. Once Multisim has evaluated this value, it uses it as the starting point. This is why the capacitor is fully charged at time zero. To see the capacitor charge, you must set the initial condition to zero volts rather than the DC operating point. Complete the following steps to set the initial condition to zero volts:
- Select Simulate » Interactive Simulation Settings.
- Under Initial conditions, click on the drop down menu to select Set to Zero.
RC circuits are generally quite simple to simulate with default settings, Multisim may output the results too quickly on your screen. To slow down the simulation, increase the sampling rate. Complete the following steps to increase the sample rate:
- Select Simulate » Interactive Simulation Settings.
- Click on the Maximum Time Step (TMAX) radio button.
- Change the value from 1e-5 seconds to 1e-7 seconds to reduce the simulation speed.