Thread: DC to AC View Single Post
 P: 692 A tank circuit will not convert a direct current to AC. If you connected a tank circuit to a DC source, the inductor, if no resistor was in series with it, would short the DC source. If you did have a resistor to limit the current through the coil, then you would simply have a direct current flowing through the coil. No current would flow through the capacitive branch when the capacitor is fully charged. Effectively, with direct current, an inductor has 0 reactance and a capacitor has infinite reactance. Inductive Reactance $$X_l=2\pi fl$$ Capacitive Reactance $$X_c=\frac{1}{2 \pi fc}$$ Both of these are measured in ohms. When dealing with RCL circuits, the total impedance is given by: $$Z=\sqrt{R^2+X_t^2}$$ $$X_t=X_l-X_c$$ At the resonant frequency, $$f_r=\frac{1}{2\pi\sqrt{LC}}$$ the total reactance is 0 and this means in a series RCL circuit that the total impedance is at it's lowest. A parallel RCL circuit operating at the resonant frequency will have maximum impedance. The frequency of a DC signal is 0 Hz so reactance doesn't come into play. Now if you're talking about pulsating DC, that's a different matter all together.