TELEVISION CAMERA COMPRISING A CONTROL CIRCUIT FOR CONTROLLING THE INTENSITY OF THE ELECTRON BEAM CURRENT IN AT LEAST ONE PICK-UP TUBE

摘要

PHN 9874 8 A television camera comprises a control circuit for controlling the electron beam current intensity in at least one pick-up tube. To prevent oscillations in a positive feedback control loop a picture signal amplifier in the control loop is provided with a multistep signal limiter. To this end, for a two-step signal limitation, a diode and a Zener diode have been provided the junction of which is connected to the base of a biased signal amplifier transistor via a resistor, a second resistor being arranged between the other terminals of the diode and the Zener diode. The junction of the first diode and the second resistor is connected via at least a second diode to the collector of the signal amplifier transistor and the base of an emitter follower transistor connected thereto. The junction of the first Zener diode and the second resistor is connected via a second Zener diode to a voltage terminal.