Adjustable stabilizer 3 27v 20a. Voltage stabilizer on a field-effect transistor

A simple circuit for regulating and stabilizing voltage is shown in the picture above; even a novice in electronics can assemble it. For example, 50 volts are supplied to the input, and at the output we get 15.7 volts or another value up to 27V.

The main radio component of this device is a field-effect (MOSFET) transistor, which can be used as IRLZ24/32/44 and others like it. They are most commonly produced by IRF and Vishay in TO-220 and D2Pak packages. It costs about $0.58 UAH at retail; on ebay 10psc can be purchased for $3 ($0.3 per piece). Such a powerful transistor has three terminals: drain, source and gate; it has the following structure: metal-dielectric (silicon dioxide SiO2)-semiconductor. The TL431 stabilizer chip in the TO-92 package provides the ability to adjust the value of the output electrical voltage. I left the transistor itself on the radiator and soldered it to the board using wires.

The input voltage for this circuit can be from 6 to 50 volts. At the output we get 3-27V with the ability to regulate with a 33k substring resistor. The output current is quite large, up to 10 Amps, depending on the radiator.

Smoothing capacitors C1, C2 can have a capacity of 10-22 μF, C3 4.7 μF. Without them, the circuit will still work, but not as well as it should. Do not forget about the voltage of electrolytic capacitors at the input and output; I took all of them designed for 50 Volts.

The power that can be dissipated by this cannot be more than 50 watts. The field-effect transistor must be installed on a radiator, the recommended surface area of ​​which is at least 200 square centimeters (0.02 m2). Don’t forget about thermal paste or rubber backing so that the heat transfers better.

It is possible to use a 33k substring resistor like WH06-1, WH06-2; they have fairly precise resistance adjustment, this is what they look like, imported and Soviet.

For convenience, it is better to solder two pads onto the board rather than wires, which are easily torn off.

Discuss the article VOLTAGE STABILIZER ON A FIELD TRANSISTOR

Printed circuit board with components and instructions in the package. In amateur radio practice, a power source is often needed that is simple in design, small in size, and has a high load capacity. This kit will allow you to assemble an adjustable voltage stabilizer with a wide range of output voltage (3...27V) and output current up to 10 A.

Printed circuit board with components and instructions in the package.
In amateur radio practice, a power source is often needed that is simple in design, small in size, and has a high load capacity. This kit will allow you to assemble an adjustable voltage stabilizer with a wide range of output voltage (3...27V) and output current up to 10 A.

The circuit consists of a powerful field-effect transistor Q1, connected as a drain follower, and a reference voltage source assembled on a TL431 chip, which has high thermal stability over the entire temperature range. The output voltage is set by a divider consisting of R2, R3 and R4. If the device needs to be used as a stabilizer with a fixed output voltage, then R3 must be replaced with a jumper. Then, the output voltage is calculated by the formula:

Where: U REF- reference voltage TL431 - 2.5 V;
UGS- gate-source threshold voltage (1…2 V).

The transistor must be installed on a radiator with a surface area comparable to the power dissipation, which can be calculated using the formula:

Where: Pq- power dissipation of the transistor;
U IN, U OUT- input and output voltages, respectively;
I NAGR- load current.

Characteristics:

Supply voltage: 6...50 V;
. Output voltage: 3...27 V;
. Maximum output current: 10 A.

Contents of delivery:

Printed circuit board;
. A set of radio components;
. User manual.

Notes:

In the case where the load is inductive in nature, it is additionally necessary to install a diode parallel to the load that dampens the reverse emissions of the EMF. The capacity of additional capacitors is selected at the rate of 1000 μF per 1 A of load current;
The maximum power dissipated by the transistor should not exceed 50 W. The device does not have short circuit protection, and if the load current or power dissipation value is exceeded, transistor Q1 may fail.

The LM317 is more suitable than ever for the design of simple, regulated sources and electronics with a variety of output characteristics, both variable output voltage and fixed voltage output. electric shock loads.

To facilitate the calculation of the required output parameters, there is a specialized LM317 calculator, which can be downloaded from the link at the end of the article along with the LM317 datasheet.

Technical characteristics of the stabilizer LM317:

• Providing output voltage from 1.2 to 37 V.
• Load current up to 1.5 A.
• Availability of protection against possible short circuit.
• Reliable protection of the microcircuit from overheating.
• Output voltage error 0.1%.

This inexpensive integrated circuit is available in TO-220, ISOWATT220, TO-3, and also D2PAK packages.

Purpose of the microcircuit pins:

Online calculator LM317

Below is an online calculator for calculating a voltage stabilizer based on LM317. In the first case, based on the required output voltage and the resistance of resistor R1, resistor R2 is calculated. In the second case, knowing the resistances of both resistors (R1 and R2), you can calculate the voltage at the output of the stabilizer.

For a calculator for calculating the current stabilizer on LM317, see.

Examples of application of the LM317 stabilizer (connection circuits)

Current stabilizer

The current stabilizer can be used in circuits of various battery chargers or regulated power supplies. The standard charger circuit is shown below.

This connection circuit uses a direct current charging method. As can be seen from the diagram, the charge current depends on the resistance of resistor R1. The value of this resistance ranges from 0.8 Ohm to 120 Ohm, which corresponds to a charging current from 10 mA to 1.56 A:

5 Volt power supply with electronic switching

Below is a diagram of a 15 volt power supply with soft start. The required smoothness of switching on the stabilizer is set by the capacitance of capacitor C2:

Switching circuit with adjustable output voltage