How does one go about triggering a switch (i.e. relay) via a resistive load in an AC circuit? For instance, if I have an AC relay (high impedance) and put the coil in series with the resistive load, it won't work: the resistive load will stop working. How does one go about triggering a relay (i.e. a switch in a different branch of the same AC circuit) via a resistive load without affecting the resistive load in any significant way? Am I missing something obvious perhaps? Dumb question? I hope this didn't belong in homework section!