Leakage Currents and Electrolytic Capacitors

Purpose:

We will construct a circuit like picture below:

The polarity of the electrolytic capacitor is important, it is not symmetric like other capacitors. When we change the polarity, the behavior of capacitor can be changed as such. The longer lead will be anode(+), and the shorter lead will be cathode(-). 

We also use R=100Ω, C=10μF connected in series, and power supply will be 5V. We will "disconnect" and "reconnect" the power supply to observe the behavior of capacitor when charging and uncharging. 

Tau = RC= 100 * 10 * 10^(-6) = 0.001s

In order to fully charged, it will take 5T = 0.005s. In our experiment, time for capacitor to be fully charged happened quickly as well.

But when it comes to discharging, our experiment result was completely off. The reason for that would be the huge internal resistance in the circuit. Since we learned that the leakage happen when value of resistor should be around 500MΩ while we only have 100Ω. 

Here is the picture of our circuit.

Capacitor Voltage-Current Relations

Purpose: In this lab, we will measure the voltage and current across a capacitor to see the relationship between them.

Pre-lab:
By measuring the voltage across the capacitor, we can easily calculate the current across it by using: Ic=Vr/R since resistor and capacitor are connected in series, so they have the same current pass through.

 Triangular of Vr and Vc

 Sinusoidal of Vr and Vc

 Picture of our circuit.

Triangular of Vr and Vc

Summing Amplifier

Purpose:

Pre-lab: Calculate Vout based on 2 Vins (Va and Vb) with Vb=1, Va=-4,-2,-1,0,1,2,3 and 5V.

R1=1.77kΩ, R2=1.19kΩ, R3=1.29kΩ

At 5V, it reaches saturation because value of Vexp vs Vtheo is off. 

Inverting Voltage Amplifier

Purpose:

Pre-lab: Based on the circuit constructed below:

We changed the value of Vin from -3V to 4V with the increment of 0.5V, and find Vout. Since this is an inverting voltage amplifier, we have value voltages from -3V to 3V symmetrical with. Vout on the left column is Vout eperimental, and on the right column is Vout theoretical. 

When it reaches saturation, we will not get the Vout experimental the same as Vout theoretical. Vcc+ and Vcc- are controlling the max value of V output in Op-amp.

Here are pictures of out circuit.

Graph of Vout vs Vin

In this graph also represents exactly the saturation and linear region as we discussed in class.