Image Number 3 for United States Patent #4335412.
A safety circuit prevents shocks, and is particularly useful with a television camera head and processing unit that are connected by a triaxial cable. The circuit applies power to the triax at the processing unit. If the current is interrupted, the power is no longer applied and a selected impedance is applied to the triax at the camera. If said impedance can be detected at the processing unit, power is reapplied to the triax. The impedance can comprise a diode, which has different effects upon different alternating signal polarities.