Patent ID: 7556726

Claim:
A circuit to clamping the voltages in the electrodes of the Contour Clamped Homogeneous Electric Field system chambers of Pulsed Field Gel Electrophoresis and for generating two identical strength but different orientation homogeneous electric fields said circuit comprises, a power supply with positive and negative outputs, an alternator with two positive and two negative outputs and an electrophoresis chamber filled with buffer solution, said electrophoresis chamber comprises an electrode array placed on the ‘m’ sides of a regular polygon having ‘k’ electrodes per side, where one side is arbitrarily selected as the L 1 side and it is made to coincide with the ‘X’ axis of a Cartesian plane, the side L m/2+1 is parallel to the L 1 side and the others sides, named ‘C’ and ‘D’ sides, are located to the left and to the right of the sides L 1 and L m/2+1 respectively being the E iC -E iD electrodes equally spaced on each side of the polygon thus existing ‘n’ E iC -E iD electrode pairs P i formed by electrodes located at the same distance from the L 1 side, where ‘n’ is equal to k·(m−2)/2 and ‘i’ is a natural number between 1 and ‘n’, said circuit further is being formed by two identical clamping circuits and each circuit alone set independently one of the two possible electric field orientations by setting potentials at electrodes of the regular polygon that homogenize the electric field, where zero volts is applied to the electrodes placed on the L 1 side, L 1 side that is another side of the regular polygon when the electric field is switched; and diodes are provided to connect the electrodes placed on the L 1 and the L m/2+1 sides to the negative and positive outputs of the power supply, respectively in each electric field orientation; and resistors and diodes are provided to generate voltage references inside each clamping circuit to polarize the E iC -E iD electrodes of each P i electrode pair transistors are provided to make stable the potentials at the E iC -E iD electrodes of each P i electrode pair against the buffer solution conductivity changes but the two E iC -E iD electrodes from each P i electrode pair are driven by one single transistor; and pairs of diodes are provided to permanently connect the two E iC -E iD electrodes of each P i electrode pair to the same node of the voltage reference through said single transistors and to polarize these two E iC -E iD electrodes at the same potential in one electric field orientation but to electrically isolate said two E iC -E iD electrodes in the other field orientation; and diodes are provided to compensate errors in the voltage pattern; and diodes are provided in order to permanently connect the two independent circuits to the same array of electrodes.