An AC constant current generator for electrostatic copying machines

A tuned collector, resonant feedback, saturated current oscillator circuit is described and analyzed for powering AC corona generators in electrostatic copying machines. The oscillator circuit is modeled as a nonlinear feedback control system and then linearized by the method of Harmonic Linearization. The resulting transfer function is utilized to establish design equations and to show the sensitivity of the constant current regulation characteristic to variations in circuit parameters. Waveforms and emperical data from a working example are included to show the regulation and adjust features of the circuit.