Blocking a Dc-current while passing an Ac-current with a capacitor in a circuit.

This project is one of the important features of a capacitor and will let you uses a capacitor to allow the flow of an alternating current but block the flow of a dc current. This circuit simply places a capacitor in series with a LED and uses a DPDT switch to connect the LED/capacitor to either a 9VDC or 9VAC. Notes: 1.The capacitor must be fully discharged before you place it in the circuit, otherwise it won't work as expected. It can be a polarized or a non-polarized capacitor, it doesn't matter! 2.For this to work effectively, you must make sure that you choose a capacitor that will fully charge and discharged withing the alternating current cycle. (this means, the capacitor must charge and discharged with the same frequency of the alternating current at 60Hz) The time constant of the capacitor is RC. but the time constant of the Ac current source is = 0.016s at 60Hz. T = 1/60 = 0.016s

published 2 years ago