TechOverflow Logo
TechOverflow

How to compute RC discharge time in Python using UliEngineering

You can easily compute the RC discharge time to reach a target voltage using the UliEngineering Python library:

rc_discharge_time.py
from UliEngineering.Electronics.RC import rc_discharge_time
from UliEngineering.EngineerIO import *

# Compute time to discharge to 10% of initial voltage
time = rc_discharge_time("10k", "100nF", 0.10)
print(f"Time to 10% discharge (10k, 100nF): {format_value(time, 's')}")

# Compute time to discharge to 1% of initial voltage
time = rc_discharge_time("1k", "1uF", 0.01)
print(f"Time to 1% discharge (1k, 1µF): {format_value(time, 's')}")

Example output

rc_discharge_time_output.txt
Time to 10% discharge (10k, 100nF): 2.30 ms
Time to 1% discharge (1k, 1µF): 4.61 ms

The RC discharge time represents the time required for a capacitor to discharge to a specific percentage of its initial voltage through a resistor. This calculation is essential for timing circuits, power-off discharge safety, and understanding the transient response of RC networks. The discharging follows an exponential decay curve, with the capacitor never truly reaching zero voltage in finite time.

The discharge time is computed using the formula: $t = -\tau \ln(\text{ratio})$, where $\tau = RC$ is the time constant and the ratio is the target voltage as a fraction of the initial voltage (e.g., 0.10 for 10%). For example, discharging to 10% takes approximately 2.3 time constants, while discharging to 1% takes approximately 4.6 time constants.

Check out similar posts by category: Electronics, Python