This circuit was found in a Radio Electronics of July 1984. It consists of the traditional 1 A source version, with the negative regulator 7912. Transformer may have 12 or 15 V of secondary and the integrated circuit must be equipped with heat radiator. Note that the output is negative voltage. This source and set with the former result in a symmetrical source if they have a common ground. Note that in the 7912 terminal 2 (middle) is not the ground. See datasheet before mounting.
