I want to find how long a capacitor takes to discharge from 12 volts to 2 volts using Qucs. I can use a voltmeter to measure the voltage across it when it charges up, but I cannot turn the power source off during simulation.

Suggestions? Thanks

  • \$\begingroup\$ I'm not very familiar with Qucs, but there ought to be a way to add a time- or voltage-controlled switch to your simulation, which can disconnect the capacitor from the power source. \$\endgroup\$ – uint128_t Jan 23 '17 at 6:02

One of the really cool lumped components in Qucs is a time controlled switch. You can specify the initial value as open or closed (see below), as well as a list of times when the switch should change state. Example of how it's used.

Qucs time controlled switch

Actually, the time-controlled switch is really a time-controlled two-state resistor with default values [Ron=0 Ω; Roff=1e12 Ω].

You can choose any value for Ron and Roff. Combined with the list of times when the state changes, this a powerful and easy-to-use time-controlled element in simulations.


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