The schematic mentioned here is a regulated 9V dual power supply circuit using ICs LM7809 and LM7909. LM7809 is a positive voltage regulator while lm7909 is a negative voltage regulator IC. Both the ICs are build to perform step down DC to DC converter tasks in electronic circuits and
provide regulated output. Use a suitable heatsink with the IC because it will get hot during operation. If heatsink will not suffciant then the ICs will shutdown for few minutes due to auto shutdown system build in the ICs. Use 110V or 230V to 12-0-12V 1A step down transformer.