Lit: the pickups of the drawbars that are out, and with the key down, the path from each to its drawbarGear pairs from the 1200 rpm main shaft: 85/104 for C, 98/80 for G, 103/100 for ENine leads, nine key contacts on nine busbars, nine drawbars: one pull per harmonicOne key's share of a tonewheel organ. A synchronous motor turns the main shaft at 1200 rpm, a gear pair gives each short shaft its own speed, and a toothed steel wheel passing a magnet makes a current at teeth times turns per second: wheel 37, sixteen teeth, gives 261.5 Hz, middle C. Every key borrows nine wheels, one per drawbar, from the sub-octave at 130.8 Hz to the 1' wheel at 2092 Hz. A drawbar pulled all the way out passes its wheel at full level, each step in is a little quieter, and the scope shows the sum. The keys 1 to 7 set classic registrations, from jazz 888000000 to the full organ 888888888. Only A at 440 Hz is exactly in tune. The integer gears put every other wheel within a few cents.