Capacitor with LED

167

03:16:54

Why after the capacitor discharges the current flow? A software bug?

published 1 year ago

xanquilty

1 year ago

I think it is due to the LED. Click into the settings of the LED, and look at it’s default voltage (2V). This correlates with the voltage the capacitor is held at after it discharges.

AntonioArts

1 year ago

Thanks for the finding xanquilty. But I still can't get my head around how to fix this. I've tried play with voltage and junction capacitance parameters but it didn't help

AntonioArts

1 year ago

It also has a strange phantom current behavior after a short delay 🤔

592azy2circuitdude

1 year ago

Are you wondering why current continues to flow through the LED after it turns OFF?

AntonioArts

1 year ago

Yes, and not only that. I can't get why there is some phantom behavior before I apply current to the scheme it appears around 10 sec after starting the simulation

592azy2circuitdude

1 year ago

Ok, good questions. I'll try my best to help answer them. The jittery phantom current, as you call it, is probably accumulated rounding errors from the solver or purposely injected noise. I've seen the same thing happen several times in circuits, especially with capacitors at a steady state.

592azy2circuitdude

1 year ago

As for the first question, I think the diode in the discharge path of the capacitor really changes the discharge characteristics from a regular RC circuit. It looks like the capacitor discharges very fast, and then it suddenly slows down. I may try some circuit transient analysis on it to find a more accurate solution. Does this help?

AntonioArts

1 year ago

592azy2circuitdude, I really appreciate your efforts to help me figure out what is happening here. I've tried to remove the diode and it solved the noise issue prior the button push, but the current still continue to flow after button release

592azy2circuitdude

1 year ago

I'm sorry, I should have said LED instead of diode. You're right. The capacitor will discharge and cause current to flow through the LED after the button is released. That is normal. Current will keep flowing through the LED even if the current is not enough to turn the LED ON until the capacitor FULLY discharges.

AntonioArts

1 year ago

592azy2circuitdude i got what you’ve meant 😉 thanks for your time with me and this circuit

592azy2circuitdude

1 year ago

Great 👍. I also learned quite a bit as I thought about your questions. Keep it up.

592azy2circuitdude

1 year ago

Hey, I just discovered an interesting workaround (if that's the right word...). Adjust the voltage setting on the LED as low as it can go. Then, increase the current setting on the LED. It helps the capacitor discharge more completely.

AntonioArts

1 year ago

Interesting idea💡Let me play around with it

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