# Separating DC & AC components

Objective

Separating AC and DC components of a voltage waveform using a capacitor.

Procedure

- Set SQR1 to 500 Hz

- Enable A1 and A2

- Adjust the horizontal scale to see several cycles.

Discussion

The observed waveforms with and without the series capacitor are shown in figure. The voltage is swinging between 0 and 5 volts. After passing through the capacitor the voltage swings from -2.5 volts to +2.5 volts.

What will you get if you subtract a 2.5 from the y-coordinate of every point of the first graph? That is what the capacitor did. It did not allow the DC part to pass through. This original square wave can be considered as a 2.5V AC superimposed on a 2.5V DC.

You may need to connect a resistor from A2 to GND to see a waveform swinging between -2.5 to +2.5 volts. Remove the resistor and observe the result.