There 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.
