Circuit lm317 voltage regulator circuit adjustable power supply. Circuit regulated power supply, adjustable from 1.2 to 30V/1.5A with the ic regulator lm317T use to substitute eliminator of piles and batteries in your circuits.

This power supply uses the LM317T integrated circuit, which allows the output voltage to be varied between 1.2 and 30V with currents up to 1.5 Amps. To be used as a battery and battery eliminator in most applications.

Unlike complicated transistor sources, this is an excellent choice for anyone who wants an adjustable power supply with a current capacity of up to 1.5 amperes. The CI lm317 is low cost and can be found with facilities in electronics stores.
In the AC connectors, you must connect a 24 volt transformer with a current capacity of at least 1.5 amperes.
The transformer that will determine the maximum voltage obtained at the output of the power supply, in this way you must choose a transformer that meets your needs.
To find out which transformer you need, make a simple account:
Tt = (Tm / 1.4142) + 2
Tt: Voltage in the Transformer
Tm: Maximum voltage
Example, I need an adjustable power supply up to 24V
Tf = (24 / 1.4142) +2 = 18.97
Then we will use a transformer with commercial value of 20VAC.

For other calculations, see this calculator for Windows

The bridge rectifier bridge accepts equivalents from 2A / 200V, such as RS207, KBL404, KBL405, KBL406, KBL407, MDA970A5, FBU4D, FBU4F, FBU4G, KBP304, KBP305, KBP306, KBP307, Ts4b05g, Kbu808.

Schematic Lm317 adjustable voltage regulator

Modifications to the power supply circuit with lm317t
To fine voltage adjustment, uses a 220 Ω potentiometer in series with the potentiometer of 4.7k.
Connect a voltmeter to the output to determine the voltage. Or use the multimeter.
You can use this source with fixed voltage, to power certain equipment, example 17.8 volts per 1 Ampere.
You can use 2 or 3 LM317 to increase current capacity up to 4 amps, use resistors of 0.22 Ω 10 W at the output of each lm317.

Suggestion for printed circuit board for power supply lm317

About LM317

The LM317 device is an adjustable three-terminal positive-voltage regulator capable of supplying more than 1.5 A over an output-voltage range of 1.25 V to 37 V. It requires only two external resistors to set the output voltage. The device features a typical line regulation of 0.01% and typical load regulation of 0.1%. It includes current limiting, thermal overload protection, and safe operating area protection. Overload protection remains functional even if the ADJUST terminal is disconnected.

About LM317HV

The LMx117HV is an adjustable 3-terminal positive voltage regulator capable of supplying 1.5 A or more currents over a 1.25-V to 57-V output voltage range. It requires only two external resistors to set the output voltage. The LMx17HV is packaged in standard transistor packages that are easily mounted and handled.

The LM317HV offers overload protection like current limit, thermal overload protection and safe area protection, which make the device blowout proof. The overload protection circuitry remains fully functional even if the adjustment terminal is disconnected.

Typically, no capacitors are needed unless the device is situated more than 6 inches from the input filter capacitors, in which case an input bypass is needed. An optional output capacitor can be added to improve transient response. The adjustment terminal can be bypassed to achieve very high ripple rejection ratios which are difficult to achieve with standard 3-terminal regulators.

Since the regulator is floating and sees only the input-to-output differential voltage, supplies of several hundred volts can be regulated as long as the maximum input to output differential is not exceeded, or in other words, do not short the output to ground.

By connecting a fixed resistor between the adjustment and output, the LM317HV can also be used as a precision current regulator. Supplies with electronic shutdown can be achieved by clamping the adjustment terminal to ground, which programs the output to 1.25 V, where most loads draw little current.

BOM  for assembling an adjustable power supply.

Last Update: 21/11/2021 20:29

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