I'm no expert but it sounds like the 555 timer chip. This chip uses capacitors and resistors as a reference time constant, then from this creates a pulse signal. By the way the output of the 555 timer is not strictly A/C sinsoidal but sawtooth.So almost like using a rapid on/off switch with C &...
Well, asking the current (I) with no resistance is like asking how long is a piece of string to find the total Resistance in a parralel circuit then =
R1 X R2 / R1 + R2
And the current can be worked out by I = V/R