QCW Tesla coil: Quasi-continuous wave

Quasi-continuous wave

QCW ramps the supply instead of switching it on flat, so the arc grows instead of appearing at once, and comes out straight and smooth instead of branching. It is a drive mode, not a topology. It usually goes on a DRSSTC, where the tank is tuned and the timing has to be tracked all the way up the ramp. It also goes on single resonant coils, where it is called ramped SSTC or QCW SSTC. That is the simpler machine and the easier place to start. There is no tank capacitor, so nothing stores a bang and nothing runs away, and the bridge current is only ever the current the bridge made. What it gives up is length, and a lot of it, because the part left out is most of what makes a DRSSTC's arc long. Loneoceans' ramped SSTC gets twelve inches off a five inch secondary. The QCW DRSSTC beside it gets seventy off five and a half: nearly the same coil, and nearly six times the arc. They are two different machines, though. They differ in the bus and the bridge as well as the tank, so read the gap as the difference between two real builds, not as the cost of removing one capacitor. On either machine the ramp brings the same problem: nothing stays still. The frequency falls as the arc loads the secondary, the current climbs, and every timing figure that was a single number on a flat burst becomes a curve across the ramp.