Time Constant This feature is a RC Time Constant (Resistor and Capacitor Time Constant). This will calculate the time of charge in capacitor, voltage rate in every each time constant, and percentage of voltage in every each in 5 time constant and will show the graph and the graph will response accordingly to the output result of time constant.

555 Timer Circuits - Flashing LED - RC Time Constant

*1*

#BLDC motor is used and the speed of the motor can be controlled by using an RC time constant by changing the resistance using a preset which is adjustable.

RC time constant illustrated. When charging a capacitor (C) through a resistor (R) it gains about 63% of the applied voltage quickly, and then takes that amount of time to charge to 86.5% and on it goes. The time per time constant depends on the resistor and capacitor value.

RC time constant - Wikipedia

Demonstration and explanation of the RC time constant using a light bulb. Video by James Dann.

*1*