Electronic Circuits: power supply

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Saturday, February 26, 2022

4A Low-Noise High-Frequency Step-Up DC-DC Converter using MAX1709 with PCB

Electronic Circuits Circuits to Assemble , Electronic Circuits

Fig. 1 - 4A Low-Noise High-Frequency Step-Up DC-DC Converter using MAX1709 with PCB

This is a DC-DC converter circuit that uses a MAX1709 series Integrated Circuit as the main component, it works with a Step-Up conversion system.

This powerful microcircuit is able to work with very few external components and deliver a fixed 3.3V or 5V or adjustable 2.5V to 5.5V voltage, with 4 Amperes of output current.

Integrated Circuit General Description

The MAX1709 sets a new standard of space savings for high-power, step-up DC-DC conversion. It delivers up to 20W at a fixed (3.3V or 5V) or adjustable (2.5V to5.5V) output, using an on-chip power MOSFET from a +0.7V to +5V supply.

Fixed-frequency PWM operation ensures that the switching noise spectrum is constrained to the 600kHz fundamental and its harmonics, allowing easy post filtering for noise reduction.

External clock synchronization capability allows for even tighter noise spectrum control. Quiescent power consumption is less than 1mW to extend operating time in battery-powered systems.

Two control inputs (ONA, ONB) allow simple push-on, push-off control through a single momentary push button switch, as well as conventional on/off logic control.

The MAX1709 also features programmable soft-start and current limit for design flexibility and optimum performance with batteries.

The maximum RMS switch cur-rent rating is 10A. For a device with a lower current rating, smaller size, and lower cost, refer to the MAX1708 datasheet.

The Circuit Schematic

In Figure 2, below, we can see the schematic diagram of 4A Low-Noise High-Frequency Step-Up DC-DC Converter using MAX1709.

The circuit is simple to assemble, there are few external components, and there is no need for adjustment, once assembled, it is ready to work, if everything is correct, of course!

The PCB tracks are bent, the main ones have their tracks at the bottom and at the top of the PCB, because the current is 4 amperes.

The capacitors are tantalum, however if you can't find them, electrolytic capacitors can be used, however for more sensitive circuits, the performance may not be as expected, but in most circuits they work very well.

The DC-DC converter supports input from 0.7V up to 5V, and at the output it maintains the stabilized voltage of 5V, however to get the promised 4 Amps, it is necessary to have at least 3.3V at the input.

Fig. 2 - Schematic Circuit 4A Low-Noise High-Frequency Step-Up DC-DC Converter using MAX1709

Components List

Semiconductors

U1 ...... MAX1709 SMD Integrated Circuit
D1 ..... B520C SMD Schottky Diode 5A

Resistor

R1 ..... 312KΩ SMD resistor (orange, brown, red, orange, gold)
R2 ..... 2Ω SMD resistor (red, black, black, gold)

Capacitor

C1, C2, C6, C7 ... 150uF SMD Tantalum Capacitor
C3 ....................... 10nF SMD Ceramic Capacitor
C4 ....................... 220nF SMD Ceramic Capacitor
C5 ....................... 100nF SMD Ceramic Capacitor

Miscellaneous

L1 .......... 1uH 5A SMD Inductor
P1, P2 .... 2-pin PCB soldering terminal blocks (Optional)
Others .... Printed Circuit Board, wires, etc.

Printed Circuit Board

In Figure 3, we provide the PCB - Printed Circuit Board, in GERBER, PDF and PNG files. These files are available for free download, on the MEGA server, in a direct link, without any bypass.

All to make it easier for you to do a more optimized assembly, either at home, or with a company that prints the board. You can download the files in the Download option below.

Fig. 3 - PCB - 4A Low-Noise High-Frequency Step-Up DC-DC Converter Using MAX1709

Files to download, Direct Link:

Click on the link beside: GERBER, PDF and PNG files

If you have any questions, suggestions or corrections, please leave them in the comments and we will answer them soon.

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USB 5V 4A Car Charger using 78S05 with PCB

Electronic Circuits Battery Charger , Circuits to Assemble

Fig. 1 - USB 5V 4A Car Charger using 78S05

This is a simple USB 5V 4A Car Charger circuit to charge a cell phone, tablet, or any other gadget that requires a voltage of 5V with a current of 2 Amperes via USB.

The circuit is a DC converter that takes power from a cigarette lighter socket in your vehicle, and converts the 12V battery voltage to a stabilized 5V voltage.

There are several models of USB chargers on the market, the problem is the high price, and the supply current is quite low, around 400mA to 600mA, smartphones currently have chargers with 1000mA, 1500mA, 2000mA...

The circuit is based on the LM78S05 IC, it is extremely easy to build, using very few components.

L78S00 Description

The L78S00 series of three-terminal positive regulators is available in TO-220 and TO-3 package sand with several fixed output voltages, making it useful in a wide range of applications.

These regulators can provide local on card regulation, eliminating the distribution problems associated with single point regulation. Each type employs internal current limiting, thermal shut-down and safe area protection, making it essentially indestructible.

If adequate heat sinking is provided, they can deliver over 2A output current. Although designed primarily as fixed voltage regulators, these devices can be used with external components to obtain adjustable voltage sand currents.

Feature

Output Current to 2A.
Output Voltage of: 5 ; 7.5 ; 9 ; 10 ; 12 ; 15 ;18 ; 24V.
Thermal Overload Protection.
Short Circuit Protection.
Output Transistor SOA Protection

Circuit Operation

In Figure 2, below, we can see the schematic diagram of USB 5V 4A Car Charger using 78S05, the Circuit's operation is pretty basic, what happens is that when you plug your USB converter into the cigarette socket of your car, it converts this 12V battery voltage to a regulated 5V voltage.

Fig. 2 - Schematic circuit USB 5V 4A Car Charger using 78S05

The total output current of the circuit is 4 Amps, 2A for each USB port, this is enough current to charge any USB device today.

The circuit has overload protection, which means that if there is a short circuit on the output, or if a device with higher current is connected to the USB converter, it will shut down, until that current is reduced to a maximum of 2A.

Components List

Semiconductors

U1, U2 ...... 78S05 Integrated Circuit Voltage regulator
LED1 .... Light Emitter Diodo, general purpose

Resistor

R1 ..... 4.7KΩ (yellow, violet, orange, gold)
RP1 ......... 10KΩ Trimpot

Capacitor

C1 .......... 47nF Ceramic Capacitor
C2 .......... 100nF Ceramic Capacitor
C3 .......... 4.700uF / 35V Electrolytic Capacitor

Miscellaneous

F1 .......... 20A - 250V soldering Fuse
P1 .......... 2-pin PCB soldering terminal blocks
P2 .......... 3-pin PCB soldering terminal blocks
Others .... Printed Circuit Board, heat sink, wires, etc.

Printed Circuit Board

All to make it easier for you to do a more optimized assembly, either at home, or with a company that prints the board. You can download the files in the Download option below.

Fig. 3 - PCB - USB 5V 4A Car Charger using 78S05

Files to Download, Direct Link:

Click on the link beside: GERBER, PDF and PNG files

If you have any questions, suggestions or corrections, please leave them in the comments and we will answer them soon.

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My Best Regards!!!

Adjustable Switching Power Supply 5.1 to 40V, 2.5 Amp using L4960 + PCB

Electronic Circuits Circuits to Assemble , Electronic Circuits

Fig. 1 - Adjustable Switching Power Supply 5.1 to 40V, 2.5 Amp using L4960

In this article, we present an adjustable power supply with a stabilized output that varies from 5.1 to 40V, with a current of 2.5 amps.

This one can also have its stabilized voltage fixed, everything will depend on the type of project you are going to use.

The adjustable power supply is based on IC L4960 which is a monolithic power switching regulator IC, delivering 2.5A at a voltage variable from 5V to 40V in step down configuration.

Features of the device include current limiting, soft start, thermal protection and 0 to 100% duty cycle for continuous operation mode.

The complete schematic diagram of the power supply is shown below in Figure 2, it is a simple but complete power supply.

Fig. 2 - Schematic Adjustable Switching Power Supply 5.1 to 40V, 2.5 Amp using L4960

CIRCUIT OPERATION

The L4960 is a monolithic step down switching regulator providing output voltages from 5.1V to 40V and delivering 2.5A.

The regulation loop consists of a sawtooth oscillator, error amplifier, comparator and the output stage. An error signal is produced by comparing the output voltage with a precise 5.1V on-chip reference (zener zap trimmed to ± 2%).

This error signal is then compared with the sawtooth signal to generate the fixed frequency pulse width modulated pulses which drive the output stage.

The gain and frequency stability of the loop can be adjusted by an external RC network connected to pin 3.

Closing the loop directly gives an output voltage of 5.1V. Higher voltages are obtained by inserting a voltage divider.

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Output overcurrent at switch on are prevented by the soft start function. The error amplifier output is initially clamped by the external capacitor Css and allowed to rise, linearly, as this capacitor is charged by a constant current source. Output overload protection is provided in the form of a current limiter.

The load current is sensed by an internal metal resistor connected to a comparator. When the load current exceeds a preset threshold this comparator sets a flip flop which disables the output stage and discharges the soft start capacitor.

A second comparator resets the flip flop when the voltage across the soft start capacitor has fallen to 0.4V.

The output stage is thus re-enabled and the output voltage rises under control of the soft start network.

If the overload condition is still present the limiter will trigger again when the threshold current is reached. The average short circuit current is limited to a safe value by the dead time introduced by the soft start network.

The thermal overload circuit disables circuit operation when the junction temperature reaches about 150°C and has hysteresis to prevent unstable conditions.

Efficient operation at switching frequencies up to 150KHz allows a reduction in the size and cost of external filter components.

The L4960 is mounted in a plastic Heptawatt power pack, and the pinouts are shown in Figure 3 below.

Fig. 3 - L4960 IC Heptawatt Pinout

Download

We provide the files with the PCB, the schematic, the PDF, GERBER and JPG, PNG and provide a direct link for free download and a direct link, "MEGA".

Click on the direct link to download the files: Layout PCB, PDF, GERBER, JPG

Fig. 4 - Adjustable Switching Power Supply 5.1 to 40V, 2.5 Amp using L4960

If you have any questions, suggestions or corrections, please leave them in the comments and we will answer them soon.

Subscribe to our blog!!! Click Here - elcircuits.com!!!

My Best Regards!!!

High Precision 5 Volts 3 Amp Voltage Regulator Circuit using TL431 + PCB

Electronic Circuits Circuits to Assemble , Electronic Circuits

Circuits with a high level of sensitivity require a stable supply, they are generally difficult to be powered by power supplies, due to the high level of sensitivity needed to provide stable voltage in the circuit.

However, we are introducing a stabilized power supply with an accurate output to power any sensitive circuit, such as microcontroller circuits, microprocessor circuits, RF transmission, PICs, and so on.

Today we are going to build a very precise circuit, which uses a very well-known component that is widely used in SMPS power supplies, especially ATX PC power supplies, “which looks more like a transistor”.

The 3-Pin TL431 Integrated Circuit, It offers better stability, less temperature deviation (VI (dev)) and less reference current (Iref) for greater system accuracy.

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The TL431 device is an adjustable tap regulator with thermal stability specified in the applicable automotive, commercial, and military temperature ranges.

The output voltage can be set to any value between Vref (approximately 2.5V) to 36V, with two external resistors. These devices have a typical output impedance of 0.2 Ω.

The active output circuitry provides a very crisp activation characteristic, making these devices excellent replacements for Zener diodes in many applications such as integrated regulation, tunable power supplies and switched power supplies.

Characteristics

Reference voltage tolerance at 25°C
0.5% (class B)
1% (class A)
2% (standard class)
Adjustable output voltage: Vref to 36V
Operation from -40 °C to 125 °C
Typical temperature deviation (TL43xB)
6 mV (temperature C)
14 mV (I Temp, Q Temp)
Low output noise
0.2 Ω typical output impedance
Sink current capacity: 1 mA to 100 mA
Application
Adjustable voltage and current reference
Secondary lateral adjustment in Flyback SMPSs
Zener Replacement
voltage monitoring
Comparator with integrated reference

In Figure 2 below, we have the schematic diagram of the High Precision Voltage Regulator Circuit with TL431 IC, the LM350 IC, provides a current of up to 3 Amps.

Fig. 1 - High Precision 5 Volts 3 Amp Voltage Regulator Circuit - TL431

With the TL431 IC, they provide a precise 5V output, which is often necessary for precision microcontrollers, sensitive equipment, that require a stabilized voltage, this circuit is ideal for that.

The power supply must provide a current of at least 3 Amps. Its input voltage must be greater than 7 Volts, to avoid overheating the LM350 IC, voltages no greater than 15V must be used.

Components List

CI 1 ......... Voltage Regulator Circuit LM350
CI 2 ......... Adjustable Regulator Circuit TL431
R1 ........... 8K2Ω Resistor (grey, red, red)
R2, R3 ..... Precision resistor 243Ω 1% (red, yellow, orange, black, brown)
P1, P2 ..... Soldering terminals on 2-pin PCI
Others ..... Printed Circuit Board, tin, wires, etc.

Download

We provide the files with the PCB, the schematic, the PDF, GERBER and JPG, PNG and provide a direct link for free download and a direct link, "MEGA".
Fig. 2 - High Precision 5 Volts 3 Amp Voltage Regulator Circuit - TL431

Click on the direct link to download the files: Layout PCB, PDF, GERBER, JPG
If you have any questions, suggestions or corrections, please leave them in the comments and we will answer them soon.
Subscribe to our blog!!! Click here - elcircuits.com!!!
My Best Regards!!!

Symmetrical Power Supply for Power Amplifiers using Calculation + PCB

Electronic Circuits Circuits to Assemble , Electronic Circuits

Fig. 1 - Symmetrical Power Supply for Power Amplifiers

For power amplifier lovers, who build their own audio power amplifiers, here is a good full wave rectifier linear symmetric power supply that will meet the power demand without leaving anything to be desired in terms of stability.

This power supply is designed for amplifiers with power up to 2500W, it will work without any problems with great stability.

Most power amplifier circuits require a symmetrical power supply, and what differs from each other is always the power required from the supply.

As we know, a good power supply with good filtering will determine the quality and final power of your amplifier.

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The complete schematic diagram of the power supply is shown below in Figure 2, it is a simple but complete power supply.

Fig.2 - Electrical schematic Symmetrical Power Supply for Power Amplifiers

However, it is worth remembering that for each amplifier power range, we can assemble a type of power supply according to the power of your amplifier.

We are presenting 3 different configurations to exemplify the different types of power amplifiers.

There are 3 examples of simplified formulas for you to calculate the power supply Current and Voltage according to the power of your amplifier.

Remembering that the PCB printed circuit board is the same for all configurations.

Configuration 1:

In this configuration, we can use amplifiers that have a total power up to 400W

We need to calculate the maximum power supply current, considering 45V supply, and the maximum power of 400W. Calculating ohms Law: P = V * I

I = P / V
I = 400/45
I = 8.88A

Now you need to stipulate the maximum ripple allowed in your design, in this case: If you set the maximum ripple voltage to 5%!

V_ripple = V_ps * 5%
V_ripple = 45V * 5%
V_ripple = 2.25V

Once the maximum ripple voltage has been stipulated, we need to calculate the capacitor for that ripple at 5% of the source, "You may be calculating the percentage that best suits your design."

Capacitor Calculation Formula : C = I / F * V_ripple

C = 8.88 / 120 * 2.25
C = 8.88 / 270
C = 0.032888 = > C = 32.888X10^-6 = 32.888uF

As our board was designed to support 6 capacitors. We can divide the entire value into uF and divide by 6 Capacitors.

C_individual = 32.888 / 6
C_individual = 5.481uF

For a closer commercial capacitors value, we have:

C_individual = 6.800uF / 63V

6 x 6.800uF Capacitor
15A rectifier bridge

Configuration 2:

In this configuration, we can use amplifiers that have a total power up to 1200W

We need to calculate the maximum power supply current, considering 75V supply, and the maximum power of 1200W. Calculating ohms Law: P = V * I

I = P / V
I = 1200/75
I = 16A

Now you need to stipulate the maximum ripple allowed in your design, in this case: If you set the maximum ripple voltage to 5%!

V_ripple = V_ps * 5%
V_ripple = 75V * 5%
V_ripple = 3.75V

Once the maximum ripple voltage has been stipulated, we need to calculate the capacitor for that ripple at 5% of the source, "You may be calculating the percentage that best suits your design."

Capacitor Calculation Formula : V_ripple = I / F * C

C = I / F * V_ripple
C = 16 / 120 * 3.75
C = 16 / 450
C = 0.035555 = > C = 35.555X10^-6 = 35.555uF

As our board was designed to support 6 capacitors. We can divide the entire value into uF and divide by 6 Capacitors.

C_individual = 35.555 / 6
C_individual = 5.925uF

For a closer commercial capacitors value, we have:

C_individual = 6.800uF / 100V

6 x 6.800uF Capacitor
25A rectifier bridge

Configuration 3:

In this configuration, we can use amplifiers that have a total power up to 2500W

We need to calculate the maximum power supply current, considering 95V supply, and the maximum power of 2500W. Calculating ohms Law: P = V * I

I = P / V
I = 2500/95
I = 26A

Now you need to stipulate the maximum ripple allowed in your design, in this case: If you set the maximum ripple voltage to 5%!

V_ripple = V_ps * 5%
V_ripple = 95V * 5%
V_ripple = 4.75V

Once the maximum ripple voltage has been stipulated, we need to calculate the capacitor for that ripple at 5% of the source, "You may be calculating the percentage that best suits your design."

Capacitor Calculation Formula : C = I / F * V_ripple

C = 26 / 120 * 4.75
C = 26 / 570
C = 0.045614 = > C = 45.614X10^-6 = 45.614uF

As our board was designed to support 6 capacitors. We can divide the entire value into uF and divide by 6 Capacitors.

C_individual = 45.614 / 6
C_individual = 7.602uF

For a closer commercial capacitors value, we have:

C_individual = 10.000uF / 200V

6 x 10.000uF Capacitor
40A rectifier bridge

Download

We provide the files with the PCB, the schematic, the PDF, GERBER and JPG, PNG and provide a direct link for free download and a direct link, "MEGA".

Click on the direct link to download the files: Layout PCB, PDF, GERBER, JPG

If you have any questions, suggestions or corrections, please leave them in the comments and we will answer them soon.

Subscribe to our blog!!! Click here - elcircuits.com!!!

My Best Regards!!!

Adjustable Power Supply 1.5V to 28V, 7.5 Amps using LT1083 IC + PCB

Electronic Circuits Circuits to Assemble , Electronic Circuits

Fig. 1 - PCB Adjustable Power Supply 1.5V to 28V, 7.5 Amps With IC LT1083

Para versão em Português, Clique Aqui!

Today we present an adjustable bench power supply from 1.5V to 28V with 7.5 amps of current, very easy to assemble, with few external components, but very functional and robust.

The circuit is based on the LT1083 integrated circuit, a 3-terminal adjustable positive voltage regulator that delivers 7.5A of current over a variable output voltage range of 1.5 to 28V with higher efficiency than currently available devices.

Each internal circuit is designed to operate with a difference of up to 1V between input and output. The guaranteed voltage drop is set to a maximum of 1.5V at maximum output current.

The internal control system adjusts the output voltage by plus or minus 1%.

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In Figure 2 - you will find the description of the input, output and ground pins. There are also other types of encapsulation, as this TO - 3P is the most common.

Fig. 2 - Pinout LT1083

The schematic shown in Figure 3 is quite simple and similar to the schematics we have shown here on our website before, such as LM350, LM338, LM317 and others, always following the line of simplicity and ease of assembly.

Fig. 3 - Schematic diagram of adjustable power supply LT1083

All LT1083 series voltage regulators are pin-compatible with the more familiar three-terminal voltage regulators, as mentioned above. These devices require a 10 μF output capacitor, which is usually included in most regulator designs.

Unlike PNP regulators where up to 10% of the production current is wasted as quiescent current, the LT1083 flows quiescent current to the load, increasing efficiency.

Features

7.5A output current
Three terminals pin-compatible
Operates down to 1V loss
Guaranteed cut-off voltage at various current levels
Line regulation: 0.015%
Load regulation: 0.1%
100% Thermal Limit Functional Test

Applications

High Efficiency Linear Regulators
Adjustable voltage regulators Constant current regulators
Battery Chargers
Desktop power supplies

Component List

IC .......... LT1083Voltage Regulator Integrated Circuit
D1 ......... KBPC1510 Bridge Rectifier diodes for 15 Amps or more as KBPC5010 for 50A
C1 ......... 4.700uF - 50V Electrolytic capacitor
C2 ......... 10uF - 50V Electrolytic capacitor
R1 ......... 120 ohm -1/4W Resistor - (brown, red, brown, gold)
R1 ......... 1.5K ohm -1/4W Resistor - (brown, green, red, gold)
P1 ......... 5K ohms potentiometer
P1, P2 ... Screw Terminal Type 5mm 2-Pin Connector
Others ... Wires, solders, printed circuit board, etc.

Download

We provide the files with the PCB, the schematic, the PDF, GERBER and JPG, PNG and provide a direct link for free download and a direct link, "MEGA".

Click on the direct link to download the files: Layout PCB, PDF, GERBER, JPG

If you have any questions, suggestions or corrections, please leave them in the comments and we will answer them soon.

Subscribe to our blog!!! Click here - elcircuits.com!!!

My Best Regards!!!

Adjustable Power Supply 1.2V to 37V, 6A, Short Circuit Protection using LM317 and TIP36 + PCB

Electronic Circuits Circuits to Assemble , Electronic Circuits

Fig. 1 - Schematic diagram Adjustable power supply circuit with short circuit protection

Para Versão Original em Português, Clique Aqui!

This is an adjustable power supply circuit from 1.2V to 37V and 6 amps of current, with short circuit protection, equipped with adjustable positive voltage stabilization circuits of three terminals LM317, plus a booster circuit, using the TIP36C, which is an inexpensive power transistor.

What makes this power supply special is the implementation of a short-circuit protection circuit, for which a BD140 PNP transistor is used.

How the circuit works

Resistor R1, which is a load sensing resistor, receives a small current flowing through it. As long as the current in the output circuit does not reach a certain current calculated through R1, the circuit behaves like a normal voltage regulator, because at small "calculated" currents there is no voltage drop in the load sensing resistor, so the Boosters TIP36C transistor does not trip.

As the current in the circuit increases, the voltage across resistor R1 increases. When this voltage reaches about 0.6 V, the "transistor cut-off voltage", the power transistors turn on and current flows through them, with the threshold determined by the maximum current supported by the power transistors.

However, we have implemented a current protection circuit that consists of a circuit equipped with a BD140 transistor with a resistor that acts as a current sensing resistor that serves to polarize the transistor and, depending on the value detected, limit the output current of the entire circuit according to a simple Ohm's Law formula that serves to set this threshold current.

Formula 1st Ohm's Law

The 1st Ohm's Law states that the potential difference between two points of a resistor is proportional to the electric current flowing in it, and that the ratio of electric potential to electric current is always constant for ohmic resistors. The formula is as follows: V = R * I

V - Voltage or electric potential
R - Electrical resistance
I - Electrical current

Knowing Ohm's Law, we can now calculate the values of the load sense resistors that activate the power stage and the bias resistors of the protection transistors that form the short circuit protection circuit.

Calculating the load resistors

First, we need to know the current of the LM317 voltage regulator, which is 1.5 amps according to the datasheet.

LM317 = 1.5A

Let us calculate R1. We know that using Ohm's law, we get the following expression:

V = R * I
V = The cut-off voltage of transistors Q2 and Q3 TIP36C is 0.6V. This is the cut-off range of the transistor. Let us call Q2 and Q3 of Qeq

I = This is the current of the regulator IC1. Let us set the operating current of IC1 to 600mA, which is 0.6A. This current is enough for the IC to work unhindered.

Then:

R1 = Vbe_Qeq / I_CI1
R1 = 0.6V / 0.6A
R1 = 1 Ohm

Calculation of the protection circuit resistance

Similarly, we need to know the total current of the selected power supply so that there is an interruption in this range. Our power supply for 6 amps.

Power supply = 6A

Let us calculate R2. We know that Ohm's law gives us the following expression:

V = R * I
V = The cut-off voltage of the transistor Q1 is 0.6 V. "This is the cut-off range of the transistor".
I = The total current of the power supply, which is 6A.

Then:

R1 = Vbe_Q1 / I_ps
R1 = 0.6V / 6A
R1 = 0.1 Ohm

Current of the power transistors

Q2 + Q3 = 25A + 25A = 50A

However, the total power of the TIP36C transistor is 125W, which means it operates at a current of 25A to 5V. Remember the above formula, P = V * I;

P = 5V * 25A = 125W.

For this circuit with a maximum voltage of 37V and transistors with a maximum power of 125W, we look as follows:

Pmax = V * I:
Imax = P / V = > Imax = 125W / 37V = > Imax = 3.37A
How are two transistors together Imax = 6,74A

Therefore, our circuit works with two TIP36C transistors to get 6 amps at the output.

Figure 2 shows the schematic of the adjustable power supply circuit with short circuit protection. Those who follow us already know this circuit very well, the difference is exactly in the implementation of the protection circuit, as we can see below.

Fig. 2 - Schematic diagram Adjustable power supply circuit with short circuit protection

Components List

CI1 ................ Voltage Regulator LM317
Q1 ................. PNP Transistor BD140
Q2, Q3 .......... Power Transistor PNP TIP36C
D1 ................. Bridge Rectifier 50A - KBPC5010
D2, D3 .......... Rectifier Diode 1N4007
R1 ................. Resistor 2W / 1Ω
R2, R4, R5 ... Resistor 5W / 0.1Ω
R3 ................ Resistor 1/4W / 220Ω
C1 ................ Electrolytic Capacitor 5600uF - 50V
C2, C3 .......... Polyester/Ceramic Capacitor 0.1uF or 100nF
RV1 .............. Potentiometer 5KΩ
P1, P2 ........... Screw Terminal Type 5mm 2-Pin Connector
Others .......... Wires, solders, printed circuit board, etc.

Source: fvml.com.br

Download

We provide the files with the PCB, the schematic, the PDF, GERBER and JPG, PNG and provide a direct link for free download and a direct link, "MEGA".

Click on the direct link to download the files: Layout PCB, PDF, GERBER, JPG

If you have any questions, suggestions or corrections, please leave them in the comments and we will answer them soon.

Subscribe to our blog!!! Click here - elcircuits.com!!!

My Best Regards!!!

Symmetrical Adjustable Power Supply 1.25V to 47V 10 Amps with Short Circuit Protection + PCB

Electronic Circuits Circuits to Assemble , Electronic Circuits

Fig. 1 - Symmetrical Adjustable Power Supply 1.25V to 47V 10 Amps with Short Circuit Protection

For Portuguese version, Click Here!

This is a Symmetrical Adjustable Power Supply can vary its output voltage from 1.25V to 47V, based on the LM317HV Linear Voltage Regulator Integrated Circuit for positive voltage and the LM337HV for negative voltage, which together with the NPN transistors TIP 35C and the PNP transistor TIP36C provide a current of 10 amps.

This schematic was taken from our partner fvml.com.br, what we did was a small change in the supported current capacitance, you can check the original circuit here Click Here!

High Voltage Adjustable Regulator

The LM317HV and LM337HV voltage regulators are adjustable 3-terminal voltage regulators capable of delivering currents of 1.5A or more over an output voltage range of 1.25V to 50V.

The LM317HV and LM337HV offer overload protection such as current limiting, thermal overload protection, and safe-area protection, that make the device breakdown-proof. The overload protection circuit remains fully functional even if the setting terminal is disconnected.

Remember, we limit the maximum output voltage of the power supply to 47V, because the LM337HV negative voltage regulator supports a maximum of 50V, unlike the LM317HV which supports up to 60V.

How the Circuit Works

After rectification and filtering, which are the first basic operations of the circuit, the total voltage coming from the transformer and rectified enters the first output block, the voltage regulator, which is controlled by the LMs Integrated Circuit and mirror image "Same function, just in a negative way".

R1 and R2 are 10 ohm resistors that have the function of Load Sensor, they receive the current flowing through the circuit, and while this current does not reach the current calculated across the resistors R1 and R2, the circuit behaves like a normal voltage regulator, because for small "calculated" currents there is no voltage drop across the Load Sensing resistor, so the Boosters Transistors TIP36C and TIP35C are not activated.

When the current in the circuit increases, the voltage across resistor R1 increases, when this voltage reaches about 0.6V "transistor turn-off voltage", the power stage is activated and current flows through it.

The Protection Circuit

The output short circuit protection circuit is formed by transistors; Q1 BD140 PNP and Q2 BD139 NPN, each for an output bias voltage.

They regulate the maximum current "Calculated", which is fixed at 10 amps, and work together with 0.06ohm resistors R3 and R4 as a current sensing resistor, which is used to polarize transistors Q1 and Q2, so that, depending on the determined value, they limit the output current of the entire circuit according to a simple formula from Ohms Law, which is used to set this limiting current.

Formula 1st Ohm's Law

The First Ohm's Law states that the potential difference between two points of a resistor is proportional to the electrical current established in it, and the ratio of electrical potential to electrical current is always constant for ohmic resistors. The formula is given by: V = R * I

V - Voltage or Electrical Potential

R - Electrical Resistance

I - Electrical Current

Armed with the knowledge of the ohms law, we can now calculate the values of the Load Sense resistors, which activates the power step, and the bias resistors of the protection transistors, which is the Short Circuit protection circuit.

Load Resistor Calculation

First, we have to know the current of the LM317hv Voltage Regulator, which according to the datasheet is 1.5 amps.

LM317HV & LM337HV = 1.5A

Let's calculate R1, knowing that the same calculation is done for R2. We know that Ohm's Law gives us the following expression:

V = R * I

V = The cutoff voltage of transistors Q3, Q4 & Q5, which follows the same principle for set Q6, Q7 & Q8, is 0.6V "Which is the Transistor cutoff region". Let's call Q3, Q4 & Q5 as a Qeq.

I = It is the current of the regulator CI1, let's put the working current of the CI1 at 300mA, which is equal to 0.3A, with this current we won't need to put a heatsink on it.

Then:

R1 = Vbe_Qeq / I_CI1

R1 = 0.6V / 0.3A

R1 = 2 ohms

Protection Circuit Resistor Calculation

Likewise, we have to know the total current of the chosen source so that there is a cut in this region. Our source is for 10 Amps.

Power Supply = 10A

Let's calculate R3, knowing that the same calculation is done for R4. We know that Ohm's Law gives us the following expression:

V = R * I

V = The cutoff voltage of transistor Q1, which follows the same principle as for transistor Q2, is 0.6V "Which is the Transistor cutoff region".

I = It is the total current of PS, which is 10A.

Then:

R1 = Vbe_Q1 / I_ps

R1 = 0.6V / 10A

R1 = 0.06 ohms

Power Transistors Current

Q3 + Q4 + Q5 = 25A + 25A + 25 = 75A

NOTE: Remembering that the power of TIP36C transistors is 125W, this means that it works with current from 25A to 5V, remember the formula above, P=V*I;

P = 5V * 25A = 125W.

For this circuit with a maximum voltage of 47V, and transistors with a maximum power of 125W, we look like this:

Pmax = V * I:

Imax = P / V => Imax = 125W / 47V => Imax = 2.66A

How are three transistors together Imax = 7.98A

And that's why our circuit uses three TIP36C transistors to achieve 10 amps at the output.

In Figure 2 we have the schematic diagram of the adjustable power supply circuit with short circuit protection, so those who accompany us already know this circuit very well, the difference is exactly the implantation of the symmetry of the circuit and the protection circuit, as we can see below.

Fig. 2 - Symmetrical Adjustable Power Supply 1.25V to 47V 10 Amps with Short Circuit Protection

The Power Transformer

The transformer must be symmetrical, i.e.: "3 wires". The transformer must be able to supply at least 10A at the output. The primary, "input voltage", must match the voltage in your area; 110V or 220Vac. The secondary, "output voltage" should be 36 - 0V - 36Vac.

Component List

Semiconductors

U1 ....................... LM317HV Voltage Regulator
U2 ....................... LM337HV Voltage Regulator
Q1 ....................... PNP BD140 Transistor
Q2 ....................... NPN BD139 Transistor
Q3, Q4, Q5 ......... PNP TIP36C Power Transistor
Q6, Q7, Q8 ......... NPN TIP35C Power Transistor
D1 ...................... KBPC5010 - 50A Rectifier Bridge
D2, D3 ............... 1N4007 Diode Rectifier

Resistors

R1, R2 ................ 2Ω / 2W Resistor
R3, R4 ................ 0.06Ω / 5W Resistor
R5, R6 ................ 5KΩ / 1/8W Resistor
R7, R8 ................ 120Ω / 1/8W Resistor
R9, R10, R11 ...... 0.1Ω / 5W Resistor
R12, R13, R14 .... 0.1Ω / 5W Resistor
RV1 .................... 5KΩ Potentiometer

Capacitors

C1, C2 ................ 5600uF - 63V Electrolytic capacitor
C3, C4 ................ 10uF - 63V Electrolytic capacitor
C5, C6 ................ 1000uF - 63V Electrolytic Capacitor

Others

P1, P2 ................. Connector 3 screw terminal 5mm 3 Pins
Others ................. Wires, Solders, pcb, etc.

We offer for download the necessary materials for those who want to assemble with PCI - Printed Circuit Board, the files in PNG, PDF and GERBER files for those who want to send for printing.

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Direct Link: PNG, PDF, GERBER files

If you have any questions, suggestions or corrections, please leave them in the comments and we will answer them soon.

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Adjustable Power Supply 1.2 to 37V High Current 20A using LM317 and TIP35C + PCB

Electronic Circuits Circuits to Assemble , Electronic Circuits

Fig. 1 - PCB Adjustable Power Supply 1.2V to 37V - 20A

For Portuguese version, click here!

This is a High Current Variable Power Supply circuit, which works smoothly *With 20 Amps. And we will use the old, wonderful, and well-known LM317, which is an Integrated Circuit regulating positive variable voltage with a range of 1.25 to 37V, and 1.5 Amps.

We obtained this circuit from our partner FVM Learning, which made it available to us, we made few changes, such as increasing the transistors that they speak of in the Original Post, and we made the PCB that was not available until now, the rest is exactly the same.

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To make an appropriate Power Supply, it is necessary to have a current well greater than 1.5A, so that’s where the power transistors come in, they’re going to increase the current without varying the voltage.

Because this variation function is up to the LM317, and the current factor is up to the transistors that in this circuit we’re going to use TIP35C.

Circuit Operation

The LM317 is a variable positive voltage regulator, which is responsible for varying the output voltage and delivering the base of the power transistors to this variable voltage.

Which together with the other transistors form a high current booster, and which depending on the amount of transistor and the sum of the currents of each transistor, we form a high current variable power supply.

The voltage that comes from the power supply enters directly into the TIP35C collector, and is controlled by varying the input voltage at the base.

And in turn the voltage that will come out of the emitter, will be directly related to the control of the output voltage of the LM317, it is necessary to use a heat sink, as this holding energy is converted into heat.

The TIP35C is a High Power Mospec transistor, with a 25A continuous collector current capacity, thus making it the perfect transistor for this project.

* It is worth remembering that this transistor has a total power of 125W, that means that following the Ohms Law, the current was calculated by the manufacturer for this transistor at 5V, let's check:

Ohms Law Formula: P = V * I

P = Power: V = Voltage: I = Current:

I = P / V ==> I = 125/5 ==> I = 25A

In our case where the power supply will go up to 37V, we can consider that:

I = P / V ==> I = 125/37 ==> I = 3.38A

Did you see the difference? We put two transistors for this work, but if you are going to use this source continuously with the maximum voltage and total current, you will need to add two more pairs in this circuit.

We can use this power supply with these parameters; Voltage, Current, maximum, but for continuous use, it will overheat the transistors and burn.

The TIP35C has 100V of Vce and Vbe, Emitter Collector Voltage, and Base Collector Voltage. Remember this, these settings refer to the TIP35C, there are other variants such as: TIP35 = 40V, TIP35A = 60V, TIP35B = 80V and TIP35C = 100V, so for this project you can use the TIP35C for greater efficiency.

The Adjustable Power Supply schematic diagram is shown in Figure 2, which shows the arrangement of the components and their connections to proceed with the assembly, which in the general context, is quite simple to assemble, and demonstrates a great effectiveness.

Fig. 2 - Schematic Diagram Adjustable Circuit - 1.25V ~ 37V, 20A CI LM317 and TIP35C

Components List

U1 ............................ LM317 voltage regulator integrated circuit
Q1 to Q6 .................. TIP35C Power Transistor
D1, D2, D3, D4 ....... 1N4007 Silicon rectifier diodes
C1 ............................ 4700uF - 63V Electrolytic capacitor
C2, C3 ..................... 0.1uF Ceramic / Polyester Capacitor
R1 ............................ 220 ohms 1 / 4W Resistor - (red, red, brown, gold)
R2 ............................ 10K ohms - 1/4 W Resistor - (brown, black, orange, gold)
R3 to R8 .................. 0.22 ohms - 5W Resistor - (red, red, silver, gold)
P1 ............................ 5k ohms Potentiometer
J1, J2 ....................... PCB Terminal Blocks - EK500V-XXP 20A - or equivalent
F1 ............................ PCB Fuse Clip Cartridge 250V 30A With Fuse 20A
Others ..................... Wires, Welds, Posts, PCB, Etc.

For those who want to download materials such as the schematic diagram in PDF, PCB Layout, GERBER and JPG, we are providing a direct link to download all the material.

Direct link to download

Click in the link to download the Files: PCB Layout, PDF, GERBER, JPG

If you have any questions, suggestions or corrections, please leave them in the comments and we will answer them soon.

Subscribe to our blog!!! Click here - elcircuits.com!!!

My Best Regards!!!

Saturday, February 26, 2022

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