Simple Variable Power Supply 1.5 – 30V, 5A

1,5-to-30V-5A-power-supplyThe power supply is based on two chips and in addition they contain only a few discrete components. In this regard, it is easy to manufacture and configuration. At the same time, the power supply provides a high level indicators, such as the smooth adjustment of the voltage in the large range, low coefficient of fluctuation, the output current up to 5A with the ability to stabilize the current, high reliability. Also, the power supply has short circuit protection.

The transformer uses the secondary winding of 25-35 volts and at a current of 5 A the output voltage is reduced not by much. Two capacitors connected in parallel 4700mkf provide a low ripple factor before the integral voltage regulator on the LM338. Potentiometer P1 can change the power supply from 1.5V to 25V. It is convenient to establish two potentiometers for coarse and consistently smooth adjustment of the tension. Double switch SW2 connects or disconnects a current executed on the chip LM317. Current regulator can limit the output current power supply in the range 0 … 1.5 A.

LM 317 pin outThe potentiometer P2 is best to use the switch to 8-10 as a fixed value potentiometer is difficult to establish the desired current. The following table shows the approximate maximum value of the output current as a function of the resistor connected between pins and Out Adj chip LM317.



20 mA

62 Ohm

30 mA

43 Ohm

40 mA

33 Ohm

80 mA

16 Ohm

350 mA

3.9 Ohm

750 mA

1.8 Ohm

1000 mA

1.3 Ohm

Power supply current stabilization mode is useful for charging batteries up to 15AH.
The instrument used a voltmeter to 30V and the ammeter to 5A.
Both devices are equipped with a heatsink that tend to heat up, especially for large values ​​of output current, it is desirable to use thernal grease. Using a different heatsink and no contact with each other. Good Thermal ensure reliable operation. Boards, transformers and all the controls and displays are placed in a large case and has holes for air circulation.

Variable power supply

Author: Andrey Veselov

Power supply is an electronic device that supplies electric energy to an electrical load. The primary function of a power supply is to convert one form of electrical energy to another and, as a result, power supplies are sometimes referred to as electric power converters. Some power supplies are discrete, stand-alone devices, whereas others are built into larger devices along with their loads. Examples of the latter include power supplies found in desktop computers and consumer electronics devices.

Tags: 12v power supply 24v power supply 5 A power supply 5v power supply 9v power supply variable power supply

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  1. author

    Alfred7 years ago

    Good design, but can you get rid of the pop up add on the ciricuit diagram link, it does not close properly