Monitoring circuit for a high-intensity glow discharge for metallurgical processes

Claim 1

Means for monitoring the electrical behavior of a highintensity glow discharge apparatus having an input circuit means, comprising: a PNP transistor and a Schmitt trigger, a first resistor in series in said input circuit, the input to said Schmitt trigger and the collector of said transistor being connected to one end of said first resistor through a second resistor; a voltage divider across said input circuit having a point therein connected to the base of said transistor; second circuit means including a source of bias voltage for applying a potential between the emitter and base of said transistor, said input circuit means and second circuit means cooperating to produce a signal in response to the voltage across said first resistor and a counter voltage dependent on the current through the collector of said transistor and said second resistor, said signal being applied to the trigger input, said voltage divider including means for varying said collector current whereby the response voltage at the trigger input is exceeded only for values of the discharge current and the discharge voltage within the range of values of the voltage-current characteristic family of the glow discharge.