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Jungletronics

# HowTo (Dis)Charging A Capacitor Using NI Multisim

## How To Use NI Multisim To Simulate a (Dis)Charge of A Capacitor — #basicTronic #Episode 11

In this post we see how a 1000uF Capacitor C charges up through the R 3,3kΩ resistor until it reaches an amount of time equal to 5 time constants known as 5T, and then remains fully charged as long as a constant supply is applied to it (12 V).

`5*τ 5*R*C = 5 * (3.300) * (1000 * 10^-6) = 16.5 seconds`

Then we will open a SPDT Switch to discharge the capacitor and measuring same time to fully discharge the capacitor.

Tool:

Multisim Live Online Circuit Simulator

https://www.multisim.com/content/ixoFBDnsEUxi9MShB5pwQm/_02_handon_charging_discharging_cap/open

Components:

`DC = 12v C = 1000uF R = 3.3k ohms Single Pole Double Throw (SPDT) `

## How to run the experiment:

To make it run both activities, run and pause the process before you switch the SPDT. Click on the graphics and you are good to go! this vid may help, I hope so…

## Theory:

During the process of charging the capacitor, the current flows towards the positive plate (and positive charge gets added to that plate) and away from the negative plate. While during the discharging of the capacitor, current flows away from the positive and towards the negative plate, in the opposite direction. A capacitor (1000 uF) is charged by connecting it to a DC voltage source using a resistor R = 3300 Ohms. Our DC power supply is rated to 12 V. Once the capacitor is connected to the DC voltage source, it will charge up to the voltage that the DC voltage source is outputting. The capacitor takes 5-time constants to charge to its maximum rating. The time constant formula is Resistance* capacitance. So to discharge, it takes too 5 times constant, 5τ, or, `5*R*C = 5 * (3.300) * (1000 * 10^-6) = 16.5 seconds` pass for the capacitor to fully discharge itself.

If a resistor is connected in series with the capacitor forming an RC circuit,
the capacitor will charge up gradually through the resistor until
the voltage across it reaches that of the supply voltage.

The time required for the capacitor to be fully charge is equivalent to about 5 time constants or 5T.

Thus, the transient response or a series RC circuit is equivalent to 5 time constants.

Notice that the charging curve for a RC charging circuit is exponential and not linear. This means that in reality the capacitor never reaches 100% fully charged. So for all practical purposes,
after five time constants (5T) it reaches 99.3% charge, so at this point the capacitor is considered to be fully charged.

And that’s how it’s done! Thank you! Bye!

## Credits & References

`NI Multisim (Software) Description NI Multisim is an electronic schematic capture and simulation program which is part of a suite of circuit design programs, along with NI Ultiboard. Multisim is one of the few circuit design programs to employ the original Berkeley SPICE based software simulation. Wikipedia`

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11#basicTronic — HowTo (Dis)Charging A Capacitor Using NI Multisim — How To Use NI Multisim To Simulate a (Dis)Charge of An Capacitor (this one:)

https://www.multisim.com/content/xNGu9JkA2saepqcLRnHpmb/02_handson_charging_discharging_cap/open

https://www.multisim.com/content/SxjwE66qtXRiPqP5SDB48b/03_handson_activity_discharging_capacitor/open/

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## J3

Hi, Guys o/ I am J3! I am just a hobby-dev, playing around with Python, Django, Lego, Arduino, Raspy, PIC, AI… Welcome! Join us!