This project is a solution to power up most of devices or projects requiring dual (+/-) adjustable power supply. Description The circuit is based on LM317 positive and LM337 negative voltage regulators. LM317 series of adjustable 3 terminal regulator is capable of supplying in excess of 1.5A over a 1.2V to 30V DC output range, due to TO3 package of IC and large heat sink the power supply can handle maximum load current. Output: +/- 1.2 to 30V DC Output Current: 1.5Amps Supply Input: 24V-0-24V AC, 2Amps Center tape Transformer CN1: Transformer Connections CN3: +/- Dual Supply Outputs P1: Positive Voltage Adjust P2: Negative Voltage Adjust D1: Positive Power Indicator D2: Negative Power Indicator From:http://www.electronics-lab.com/project/dual-adjustable-power-supply/