A circuit assembly is provided for producing a test voltage for testing a test object, comprising two high voltage sources for producing a positive and negative high voltage of variable amplitude at respective outputs thereof and a high voltage switch assembly, which is arranged between the outputs of the two high voltage sources and the test object and which can be switched suitably in order to successively charge and discharge the test object, wherein furthermore a closed-loop controller is provided, which measures the present test voltage on the test object and acts on the high-voltage switch assembly in order to charge and discharge the test object in a defined manner in dependence on the measured test voltage.