1A Power Supply with 0 to 15 Volts Adjustable Output

The objective of the circuit is to create a power supply that would produce an output of 0 V to 15 V at 1 A current.
Terminology

• 2N3055 – a complementary Silicon Epitaxial-Base planar NPN transistor mounted in Jedec TO-3 metal case for use as power transistor
• Bridge Diode – also known as bridge rectifier which has four diodes arranged in a bridge configuration where the output voltage has the same polarity with either polarity of the input voltage

Circuit Explanation

The construction of this power supply circuit is very simple in such a way that the components used are easy to be located while the cost is very cheap. With the biggest provided current at 1 A, the output voltage is adjusted for minimal ripple effect and stabilized in the range of 0 V to 15 V DC. This is made possible by the standard transformer output of 1.5 A with a primary winding voltage of 220 V and secondary voltage of 18 V. The current is being limited by the Zener diode D1 with a rating of 18 V and 1.5 W. The linear potentiometer R2 is responsible for the regulation of current.
The power transistor Q1 is a classic type that would require to be placed in a suitable heatsink to suppress the high heat dissipation during the operation of the circuit. The heat dissipation will be continuous during the presence of the highest current. The bridge diode GR1 will provide full wave rectification from the AC input which will also convert the incoming alternating current (AC) input into direct current (DC) output. One good feature of the bridge diode is maintaining the same polarity of the output regardless of the polarity of the input.

Part List

R1= 56ohm 2W R2= 330ohm Lin. pot. C1= 2200uF 35V C2= 100uF 35V

C3= 10uF 25V C4= 220uF 25V C5= 100nF 100V GR1= 4 X 1N4007

Q1= 2N3055 T1=220V@18V 1.5A D1= 18V 1.5W  zener

Application

The 15V/1 A power supply may be used to handle home automation control system which can be powered by 12 Vdc. They can be made into power adapter models to support a wide variety of applications such as TFT monitors, broadcasting, laptops, digital cameras, telecommunications, PSP’s, routers, notebooks, guitar effects pedals, KVM extenders, iPod’s, scanners, CCTV’s, printers, cassette players, radios, and other portable applications.
Source:users.otenet.gr/~athsam/power_supply_0_15v_1a.htm