Control signal and isolation circuits

Claim 1

In a system for controlling the excitation of an electrical load over a range of intensity levels wherein a controlled generating means adapted to be located remotely from the electrical load establishes the level of load energization, comprising: (a) said controlled generating means comprising means for generating a pulse width modulated waveform having a variable duty cycle and load setting means for setting the duty cycle as a function of the desired level of load excitation; (b) load control means, d-c isolation means and detection means all adapted to be positioned remotely from said controlled generating means; (c) said d-c isolation means comprising input means for electrical connection to said controlled waveform generator and output means capable of providing a pulse width modulated waveform responsive to the waveform from said controlled generating means; (d) said detection means being connected in circuit between the output means of said d-c isolation means and the load control means to provide to said load control means an analog input signal of magnitude representative of the duty cycle of said pulse width modulated waveform; (e) said controlled generating means being adapted to generate the pulse width modulated waveform having a desired duty cycle independent of any feedback from the output of said d-c isolation means; (f) said load control means being constructed to vary the excitation of an electrical load over a range of intensity levels and to establish the level of excitation as a function of the duty cycle of the pulse width modulated signal generated by said controlled generating means.