# Simulating charge-discharge of a capacitor in TINKERCAD

I have been using TINKERCAD circuits for a while now, and I have been able to simulate almost every basic thing in circuits. But when it comes to simulating the charging and discharging times of a capacitor with the oscilloscope, then I can not show the charge-discharge phases... Any help here?

Is it true TINKERCAD is not good simulating capacitors?

Thanks

• What do you imagine is the impedance of the faux oscilloscope? If your capacitance value is large enough (I've no idea its value right now) and if Tinkercad waits until things have stabilized before displaying things for you, then it's no shock. The "oscilloscope" would just see a square wave centered over 0 V. (The capacitor would just block DC, in short, after enough time has occurred that the capacitor itself holds a relatively fixed voltage across it and the resistors [scope resistance + circuit resistor] are neither charging nor discharging it much anymore.)
– jonk
Apr 21, 2021 at 2:33
• The capacitor is shorted by the metal strip in the breadboard.
– tim
Apr 21, 2021 at 7:30

As the other answer explained well (scope connection / ground wrong, and capacitor shorted by solderless breadboard), your schematic should look more like this:

simulate this circuit – Schematic created using CircuitLab

If you run the simulation above, you'll get this plot:

As pictured, the circuit shown has time constant $$\\tau\$$:

$$\tau = R C = (100 \ \Omega) (1 \ \mu \text{F}) = 100 \ \mu \text{s}$$

The $$\V_\text{in}\$$ input switching interval, i.e. the half-period of the square wave function generator, is $$\t_\text{hp}\$$:

$$t_\text{hp} = \frac {1} {2 f} = 500 \ \mu \text{s}$$

The characteristic shape of this RC charging-discharging is determined the number of time constants of settling $$\n\$$:

$$n = \frac {t_\text{hp}} {\tau}$$

If $$\n\$$ is large, then the output will look more like the input, with only a brief analog edge. If $$\n\$$ is small, then the output will look more like relatively small ripple around the long-term average.

With $$\n = 5\$$, the plot shown here is somewhere in the middle of behaviors. After 5 time constants, the output of the first-order system has settled to within $$\e^{-5} = 0.7\%\$$ of its final value.

• you can not imagine how grateful I am with your help. I finally could simulate the capacitor charge-discharge phases using TINKERCAD. Thank you very much Apr 22, 2021 at 14:25

Your scope connection is wrong. If you want to see the voltage of the cap, you need to connect the scope to both terminals of the cap.

Also note that you shorted the cap on the board (vertical holes are connected).

You can not imagine how grateful I am with your help. I finally could simulate the capacitor charge-discharge phases using TINKERCAD. Thank you very much.