Capacitor charge and discharge

[Hassss]

Hello 

I have some work regarding capacitors charge and discharge, and I need to apply them to multi sim and compare results from mathematical calculations, to calculations from multisim. However im new to Multisim and really unsure how to use it, and which instruments I acquire. Id sincerly appreciate your help if you do not mind.

I have to calculate and show the RC time constant in multisim along with voltage, then calculating the time it takes the voltage on the capactior to equal n Value, and then for 3CR, and then after a certain time period what is the remaining voltage and current across a capacitor. 

Its just 4 steps but ive described them quiet briefly.

If you can point me in the right direction id sincerly appreciate it

Hass

[Chen_T]

Hi Hass,

I created a simple RC circuirt as an example. 

I choose the PULSE_VOLTAGE as the source to see the charging and discharging process, the parameters are shown below:

Initial Value = 0V

Pulsed Value = 5V

Pulse Width = 500ns

Period = 1000ns

When simulating the circuit, please select Analyses: Transient Analysis from the simulate menu. This opens the Transient Analysis parameters window.

In the Analysis Parameters tab, set the start time at 0 and the end time to 1e-006.

In the Output tab, add V(1) and V(2) to the selected variable list so that you can plot both the source voltage and the capacitor voltage.

Click the Simulate button and  a Grapher View window will appear showing your plot. 

If you want see the current add I(R1) to the output tab and it will show a similar plot like the one below

When you have the output results, you can add cursors on the figures to see some cirtain values at cirtain time.

By the way, we usually say voltage across sth and current through sth. The saying "current across a capacitor" is not an appropriate one in Electrical Engineering.

If you have any other questions feel free to post them.

Hope this helps! 🙂

[Doc.]

Hi,

 I am building a series/parallel capacitive circuit for my Physics Class - having been sent on-line to teach. I set up this circuit with my 5 capacitors (in lab I usually use 100+ microfarad caps with a 1200 ohm resistor, so the student can see the charging/discharging in real time and for the PASCO/Capstone equipment we use, the student collect to current as a function of time and then integrate the current to get the charge) and the students measure the total capacitance and individual capacitance using an LRC meter. They vary the voltage and then measure the total current. Then, for an exercise, they pick one of their voltages and then measure the charge on each capacitor and compare it using the series/parallel rules for capacitors. My question is how can I make your set up here work in real time. I set the square wave power supply period for 20 seconds, since I would like them to see the discharging and the charging but when I run the simulation is is completed instantly.

Also, can the current data going to each capacitor be integrated to get the charge on the capacitors?

Thanks for your help.

Tom McCarthy

GCU, Phoenix