Abstract: A plurality of controlled avalanche semiconductor elements, are connected in series and are irradiated with a controllable quantity of light to form circuits which in principle can switch an unlimited high voltage or can control such a voltage. Dissipating auxiliary means to obtain a uniform voltage distribution cross the circuit are not required. As a light source, light-emitting diodes can be used so that the elements can be controlled at a low-voltage level and with DC separation the circuit can be used in high-voltage amplifiers, high-voltage regulators or high-voltage stabilizers, deflection voltage generators, high-voltage switches in X-ray apparatus, lasers, ignition systems in combustion engines etc.