Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <FutureT-at-aol-dot-com> Lance, Sounds like maybe a 12000uF, 40V DC electrolytic cap. If so, it's absolutely worthless for a Tesla coil. Tesla coils need HV AC high frequency low loss, or pulse rated caps with fractional uF ratings to give resonance in operation. Cheers, John