This is a dual regulated and stabilized power supply, usually used to supply amplifier circuit. There are 3 output that are (+) voltage, (0) Ground (normal), and (-) voltage. The current output max about 0.3-0.5 A.
Please take a note that this circuit require center tap transformer. for example, if you need 12v output, you should connect J1 to 15v transformer output, J2 connected to 0v and J3 connected to another 15V.
The IC works ac stabilizer and regulator. There are 2 types of IC that are:
78xx > for positive voltage
79xx > for negative voltage
“xx” is the voltage output from IC. example, use 7809 if you need +9VDC output and 7909 for -9VDC output. The IC input voltage should be at least 12V.