In this video we will see how to assemble an adjustable power supply, with the lm317 integrated circuit, and other electronic components. This project is ideal, if you want to put together an economical source, easy to make, and perfect to insert into our protoboard. Included is the printed circuit.
The LM317t is a monolithic integrated circuit in TO-220, intended to be used as a positive adjustable voltage regulator.
It is designed to supply more than 1.5 A of charging current with an adjustable output
voltage in a range of 1.2 to 37 V. The rated output voltage is selected by a resistive divider, which makes device exceptionally easy to use.
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Pinout
Specifications
- : Adjustable
- Number of outputs: 1
- Minimum input voltage: 4.2 V
- Maximum input voltage: 40 V
- Minimum adjustable output voltage 1.2 V
- Maximum adjustable output voltage: 37 V
- Output current: 1.5 A
- Minimum operating temperature: 0oC
- Maximum operating temperature: 125oC
- Encapsulated: TO-220
- 3 pins
WHAT IS A VOLTAGE SOURCE
A voltage source is a circuit like the one that can provide constant voltage and current. For this purpose the LM317 circuit requires an input voltage source. For example, the difference between the input and output of the LM317 controller should be at least 4.2V and a maximum of 40V.
The LM317 voltage regulator has the characteristic of having a variable configuration. This adjustable source is controlled via variable resistance.
CIRCUIT LM317
The LM317 circuit has different configurations to regulate voltage. For example, the most commonly used configuration is that of variable controller from 1.2V to 37V. To achieve this adjustable power supply, it is required to connect the next circuit. This source requires a resistance of 470 Ohm and a potentiometer of 10k. Then, two of the potentiometer terminals will connect to each other (one in the center and one edge). These connections will be attached to the resistor terminal and the controller adjustment pin. Also the other terminal of the potentiometer is grounded as well as the ground of the input source. The regulated voltage output (the center pin) is connected to the 1k resistor terminal. Finally, the positive of the input source is connected to pin 3. The following figure shows the resulting circuit.
Circuit
Materials:
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