# Best DC power supply 3Amp to adjust 1.2V-20V & 3V-6V-9V-12V

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This is the high quality power supply to provide high current 3A. And still adjust voltage in steps from 3V, 6V, 9V, 12V. adjust voltage is continuous 1.25V to 20V. Using LM317T and 2N3055 are main parts so easy to made and cheap.

Friends would known the power supply as well. Because you must use in various circuit experiment. It originally had a small supply current, when found projects that uses lot of current. Such as an audio amplifier circuit so provide current is not enough.
This project can help you. Because of provide high current 3A. And still adjust voltage in steps from 3V, 6V, 9V, 12V. adjust voltage is continuous. And you do not have to worry. This creates a simple and economical. If interested, please read on.

How it works
In the circuit below can be seen that, when opening switch S1 is current through the transformer. To convert from 220V AC to 18V, then through diode bridge rectifier BD1. But is a DC supply that still not smooth. Then, a filter capacitor C1 serves electricity, out of BD1 to be more smooth with the LED1 to show that power is supplied to already.
When the filter current is smooth on one order. The current will through the regulator circuit that the main components are IC1(LM317T) and Q1(2N3055).
-IC1 is the regulator IC number : LM317T.
-Q1 is power transistor NPN type number : 2N3055.

– Before the DC volt through IC1 would have C2 served filter noise off. When we adjust the variable resistor VR1 or rotary switches S3 twist choose it. Will cause changes the voltage at the ADJ pin and OUT pin of IC1. Which will be resulting the voltage drop across the base pin and the emitter pin of transistor Q1 changes. Makes the voltage on the connector is changed accordingly. And before the voltage is applied to current C3 filter to smooth again.
Detail see in circuit image.

power supply regulator 1_2V-20V and 3V-6V-9V-12V 3Amp With LM317T and 2N3055

How to build
This project is not much equipment. I soldered components onto the perforated board. Place position equipment according to the circuit. Q1 should be hold on a large heat sink. It is very hot during use. Switches are connected correctly. If you are a beginner must sedation. Before entering power should review several times. To prevent damage, do not happen. In particular, Position pin diode, Capacitor electrolytic, transistors, IC1.
If something goes wrong, you will have the full power and 3A, which are talented enough to, show you how. “I make with myself, have a proud and active needs, in save “.