Making Adjustable DC Power Supply with LM317

DC power supplies are a must for our desks, easy to use and functional makes our lives easier, we can make our own DC power supply in the 2V-20V range at low costs even though the prices on the market are cliff, I move on to our content without extension.

What is LM317K Transistor

The LM317K transistor is an adjustable voltage regulator. Output Voltage values between 1.25V and 37V this value is determined according to the input voltage, the maximum output current is maximum 1.5A, so it is necessary not to use it in projects that attract high current. The maximum difference between input and output voltages is 40V. The resistance connected to the adjustment pin is relative to the output voltage. power supply

Elements Used in The Circuit

  • LM317K / Cooling Block
  • 220:24 20W Transformer
  • 1A Insurance
  • 1N4001 Diode x4
  • 100pF x2 & 2200uF Capacitor
  • 10k Ponsiometer
  • Preferably DC Volt and Current Indicator

Circuit Diagram

power supply

Schema Description

On the left side of the circuit, 220V AC (city line) is reduced to the desired voltage with the help of transformer, where I used a transformer that reduced to 220Vu 24V, based on the LM317K regulator. The voltage at the transformer outlet was converted to DC voltage using the bridge rectifier, i.e. 4 1N4001 diodes. With the added C1 capacitor, we have brought the waveform a little more stable. In the second part of the DC Power supply circuit, we used the LM 317 regulator to adjust and regulate the output voltage, so that the output current of the DC Power supply performed is not affected by the load resistance and output voltage changes that will be connected to the output of the power supply. LM 317 has performed the circuit section, which provides the change of output voltage and the regulation process. The output voltage in the power supply circuit is adjusted with the 10K ohm Pot connected to the 2 legs of the LM 317. You also need to make a few calculations for the LM317 for different voltage values. power supply

Posiometer Tests

power supply

Ponsiometer Output Voltage around 8%:5V

power supply

Ponsiometer Output Voltage around 100%:23V