Fig. 1 - Electronic Resistive Load - 50A Power Supply Test with PCB

You know that moment when you have a power supply to fix, you do the service and the supply works, but you don't know if it will support a large load?

I came across a problem like this, and I decided to make my own resistive electronic load, and share it with our subscribers, and for you who visit us, welcome!

Transistor Description

The Circuit

The schematic diagram of the Electronic Resistive Load - Power Supply Test!, is shown in Figure 2 below, it is a simple circuit to assemble, there are few external components to solder, however it is a circuit of great quality and stability.

Fig. 2 - Electronic Resistive Load - 50A Power Supply Test

Component List

• Semiconductors
• Q1, Q2 .... IRL44N Mosfet Transistor
• D1 ........... 1N4731 1W Zener Diode
  
  
• Resistors
• R1 ........ 1.8KΩ resistor (brown, grey, red, gold)
• R2 ........ 0.22Ω resistor (red, red, silver, gold)
• POT1 ... 220KΩ Potentiometer
  
  

• Miscellaneous
• P1 .... Screw Terminal Type 5mm 2-Pin Connector
• Others .... PCB, Heat Sink, tin, wires, etc.
  
  

The PCB - Files to Download

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 Electronic Resistive Load - 50A Power Supply Test

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!

Fig. 1 - How to Wire LEDs in 110V or 220 Volts - 6 Different Circuits! Formulas & Calculations!

Today we will show you 6 different ways to wire 3mm or 5mm LEDs, which are low voltage DC components, into a 110V or 220V AC voltage grid!

We can use LEDs in several ways connected to 110V or 220V power grid, knowing that some types of connections bring advantages over others, and that each type has its characteristics that best fit each specification. 

We will use some basic formulas to calculate the components in our circuit, for this we will use the capacitive reactance formula, and the Ohms Law formula.

So let's start by showing the basic formulas that we will use with the models we made in this post. 

We'll apply the basic formulas as needed, so we'll start first by determining the supply voltage. 

CAUTION! 

The working voltage

It is necessary to know that our grid voltage has peak voltages, as showing in Figure 2 below, and for our safety we will use the peak to peak voltage (VPP) in our calculations.

Fig. 2 - Peak to Peak 110Vac Calculation - VPP

The calculation is determined by the mathematical equation:

• VP = VAC * √(2)

As our power grid is 110VAC:

• VP = 110 *1.414
• VP = 155.54VAC

If you use the 220VAC power grid:

• VP = 220V * 1.414
• VP = 311,08VAC
  
  

The LED

Determine the resistor resistance:

Determine the Resistor's Power:

• P = R * I²

Determine Capacitive Reactance:

This model is the simplest we have, and it is very often used in cheap electrical extensions of those Chinese products, and also as a Pilot lamp in equipment,... 

The circuit presented has only one resistor R1, which limits the current that passes through the LED, and is connected in series with the LED, as we can see in Figure 3 below.

Fig. 3 - Wire LED in 110v or 220V Circuit 1 - ELC

2° Circuit:

This model is still quite simple, it is a circuit widely used also in cheaper electrical extensions of those Chinese products... 

The circuit presented has a resistor R1, which limits the current that passes through the LED, and a Diode, which polarizes the AC voltage coming from the power grid, which is connected in series with the LED, as we can see in Circuit 2.1 in Figure 4 below. .

We also have Circuit 2.2, which is the same circuit, but we have added a 2.2uF capacitor that serves to minimize the ripple voltage in the circuit. 

Fig. 4 - Wire LED in 110v or 220V Circuit 2 - ELC

Designing the Circuit

Just like the previous circuit, the calculations are the same, we already calculated the resistance, after all the process, it was 12K with 5W of power.

Project Finished - Circuit 2

Here we finish the development of our circuit 2, the calculated values are

• LED1 ....... Light Emitting Diode 3.2V / 20mA
• D1 ............ 1N4007 Diode
• C1 ............ 2.2uF / 25V Electrolytic Capacitor (Optional)
• R1 ............ 12K / 5W resistor for 110V. (27K at 220V).

Advantages:

• It is a simple and easy circuit to assemble
• Only 3 or 4 components
• Safer circuit for LED lifetime

Disadvantages:

• Voltage dissipation will be on the resistor (Joule effect)
• Consumption higher than necessary
• Circuit operating in half wave, LED half off
• Low Efficiency
  
  

3° Circuit

This model, different from the previous one, adopts a rectifier bridge, this implies that the energy that comes to the LED, is no longer a half wave, but a full wave, which gives more brightness to the LED.

The circuit presented has a resistor R1, current limiter, and a bridge of diodes, which polarize the AC voltage that comes from the grid, and feeds the LED, as we can see in Circuit 2.1 in Figure 5 below.

We also have Circuit 2.2, which is the same circuit, but we add a 2.2uF capacitor that serves to minimize the ripple voltage in the circuit. 

Fig. 5 - Wire LED in 110v or 220V Circuit 3 - ELC

Designing the Circuit

Just like the previous circuit, the calculations are the same, we already calculated the resistance, after all the process, it was 12K with 5W of power.

Project Finished - Circuit 3

Here we finish the development of our circuit 2, the calculated values are

• LED1 ....... Light Emitting Diode 3.2V / 20mA
• D1 ............ 4 x 1N4007 Diode, or a diode bridge any model
• C1 ............ 2.2uF / 25V Electrolytic Capacitor (Optional)
• R1 ............ 12K / 5W resistor for 110V. (27K at 220V).

Advantages:

• It is a simple circuit to assemble
• Only 3 or 4 components
• Full wave, which gives more brightness to the LED.
• Safer circuit for LED lifetime

Disadvantages:

• Voltage dissipation will be on the resistor (Joule effect)
• Consumption higher than necessary
• Low Efficiency
  
  

4° Circuit:

This model is simple, but works in a more efficient way, since the heat dissipation is no longer tied to the Current Limiting Resistor, which dissipated all the voltage in the previous circuits.

This circuit is widely used in Mosquito Bats, rechargeable flashlights, i.e. cheaper Chinese products. 

In this circuit we replaced the current limiting resistor with a capacitor. When a capacitor is connected to an AC source, it allows current to flow in a circuit.

With the process of successive charge and discharge of a capacitor, it gives rise to a resistance, in the passage of current in the circuit, and this resistance is called capacitive reactance. With these properties, we can use the capacitor in our circuit as a resistor.

In the case of the capacitor, all of this energy is used, because the capacitor needs to charge and discharge, it "holds" the energy and therefore does not consume it, making the circuit much more efficient. 

We also have Circuit 4.2, which is the same circuit, but we have added a 2.2uF capacitor that serves to minimize the ripple voltage in the circuit. The complete circuits are in Figure 6 below.

Fig. 6 - Wire LED in 110v or 220V Circuit 4 - ELC

5° Circuit:

This model is a more complete and improved circuit, because it brings with it a diode bridge, improving efficiency even more, since the LED will no longer work for half a wave period, but for a full wave period.

This circuit is widely used in small luminaires, even in LED lamps, rechargeable flashlights, or in commercial products. 

This circuit is the junction of circuits 3 and 4, thus forming an efficient circuit, with good LED brightness, with full wave, it is almost the perfect circuit. 

The circuit presented has a diode bridge, which polarizes the AC voltage coming from the mains, which is connected in series with the LED, as we can see in Circuit 5.1 in Figure 7 below.

We also have Circuit 5.2, which is the same circuit, but we add a 2.2uF capacitor that serves to minimize the ripple voltage in the circuit.

Fig. 7 - Wire LED in 110v or 220V Circuit 5 - ELC

Designing the Circuit

First you need to determine the capacitive reactance, which was already done in the previous circuit, the capacitance is 5.340Ω or 5.3K.

Project Finished - Circuit 5

We finish here the development of our circuit 5, the calculated values we will have:

• LED1 ....... Light Emitting Diode 3.2V / 20mA
• D1 ........... 4 x 1N4007 Diode, or a diode bridge, any model
• C1 ........... 560nF / 250V Polyester Capacitor
• C2 ........... 2.2uF / 25V Electrolytic Capacitor (Optional)

Advantages:

• It is a simple circuit to assemble
• Only 3 or 4 components
• Safer circuit for LED lifetime
• No consumption of excess heat energy (Joule effect)
• High Efficiency
• Circuit operating in full wave, LED always on

Disadvantages:

• High current in the initial steady state of the capacitor, causing those "pops" and sparks in the socket.
  
  

6° Circuit:

This model is more complete and, like the previous circuit, is more efficient. This circuit is widely used in small light fixtures, some LED lamps, rechargeable flashlights, and in some commercial products. 

The circuit presented is identical to circuit 5, with the only difference that we put a resistor R1, that serve to limit the capacitor inrush current. A diode bridge, which polarizes the AC voltage coming from the mains, which is connected in series with the LED, as we can see in Circuit 6.1 in Figure 8 below.

We also have Circuit 6.2, which is the same circuit, but we have added a 2.2uF capacitor that serves to minimize the ripple voltage in the circuit.

Fig. 8 - Wire LED in 110v or 220V Circuit 6 - ELC

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

This is a power supply designed to be used in a technical bench, based on the LT1083 integrated circuit, which is an adjustable 3-terminal positive voltage regulator. 

Which provides a current of 7.5A in a variable output voltage range of 1.5 to 28V, and even has short circuit and over temperature protection.

 

The Circuit provides a symmetrical output, which pleases all of us engineers, technicians and designers, this type of power supply, as it brings us great efficiency for application in technical benches, mainly for testing audio amplifiers.

LT1083 IC Description

The  LT1083  positive  adjustable  regulator  is designed to provide  7.5A with higher efficiency than currently  available  devices.  

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

Fig. 2 - Pinout LT1083

All  internal  circuitry  is designed to operate down to 1V input to output differential, and the dropout voltage is fully specified as a function of load current. 

Dropout is guaranteed at a maximum of 1.5V at  maximum  output  current,  decreasing  at  lower  load currents. 

On-chip trimming adjusts the output voltage to 1%. The current limit is also trimmed, minimizing the stress on both the regulator and power source circuitry under overload conditions.

You may be interested in: 

• Switched Power Supply SMPS 13.8V 10A using IR2153 IC and IRF840, with PCB
• Adjustable Power Supply 1.2V to 37V, 6A, Short Circuit Protection with LM317 and TIP36 + PCB
• Symmetrical Adjustable Power Supply 1.25V to 47V 10 Amps with Short Circuit Protection + PCB
• Adjustable Power Supply 1.2 to 37V High Current 20A with LM317 and TIP35C + PCB
• Adjustable Power Supply 1.25v to 57V, 6 Amps with TIP36C + LM317HV + PCB
• Adjustable Power Supply 1.25v to 33V, 3 Amps with LM350 + PCB
• Stabilized Power Supply 13.8V High Current 10 Amps with PCB

The LT1083  series  devices  are  pin  compatible  with  older three terminal  regulators. A 10μF  output  capacitor  is required on these new devices; however, this is usually included in most regulator designs.

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

Features

• Three-Terminal 3.3V, 3.6V, 5V, 12V or Adjustable
• Output Current of 3A, 5A or 7.5A
• Operates Down to 1V Dropout
• Guaranteed Dropout Voltage at Multiple Current Levels
• Line Regulation: 0.015%
• Load Regulation: 0.1%
• 100% Thermal Limit Functional Test
• Adjustable Versions Available
  
  

How the Circuit Work

The circuit operation is quite simple, and its operation is applied with an artifice that we did to join two adjustable power sources into one.

Since we don't have "as far as I know", a regulator of the same negative line, like what happens with the regulators LM317, LM7812 and etc.

The bridges of diodes KBPC5010 D1 and D4, are responsible for rectifying the circuit, this diode bridge is able to support currents up to 50A. 

I know it's an exaggeration, but it was what I had here, you can be putting with lower current, as the KBPC1510, for 15A, or the KBPC1010 for 10A.

The capacitors C1 and C3, are electrolytic capacitors responsible for filtering the circuit, we use them of 10,000uF, but if you don't have one you can put one of 8,000uF. Remembering that they have to be able to avoid Ripple in the power supply.

The resistors R1 and R3 are the limiters for LED1 and LED2, which are used as voltage signaling for the two sources.

The voltage that comes already rectified and filtered enters the Positive Voltage Regulators, as we can see in the circuit, they are identical circuits, and through the double potentiometer the output voltage regulation is done, ranging from 1.5V to 28V.

The diodes D2, D3, D5, and D6, are for reverse voltage protection that can arise from the circuit and damage the Regulators, and the diodes protect these voltages in the regulators.

The resistors R2 and R4, are responsible for the Feedback voltage, or feedback, they keep the output voltage stable, they are resistors that if you have conditions, put the ones with low error percentage, such as precision resistors with 1%.

And finally, the capacitors C2 and C4, are for spurious filter, if you can afford it, it is preferable tantalum capacitors. 

The Circuit Diagram

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

Fig. 3 - Schematic Diagram 1.5V to 28V, 7.5 Amps Adjustable Symmetric Power Supply using IC LT1083

The Power Transformer

The transformer must be symmetrical with center tape open, this means that it will to have two independent winding: "2 Wire + 2 Wire", as illustrated in Figure 4 below. 

Fig. 4 - Symmetrical Transformer with Independent secondary winding

The transformer must be able to supply 8A at the symmetrical output. The primary voltage, “input voltage”, must correspond to the voltage in your area; 110V or 220Vac. 

The secondary voltage, “output voltage”, should be 21Vac in each coil, because after rectification it will supply the circuit with 30Vdc.

Component List

• Semiconductors
• U1, U2 .................. LT1083 Voltage Regulator  
• D1, D4 .................. KBPC5010 - 50A Rectifier Bridge *See Text
• D2, D3, D5, D6 .... 1N4007 Diode Rectifier 
• LED1, LED2 ........ Light Emitter Diode (General Use)
  
  
• Resistors
• R1, R3 ....... 2K7Ω 1/8w Resistor (red, violet, red, gold) 
• R2, R4 ....... 120Ω 1/8w Resistor (brown, red, brown, gold) 
• RP1 ........... 5KΩ Double Potentiometer 
  
  
• Capacitors
• C1, C3 ........ 10.000uF - 45V Electrolytic capacitor 
• C2, C4 ........ 10uF - 45V Electrolytic capacitor 
  
  
• Miscellanies
• P1, P2 ........ Connector 2 screw terminal 5mm 2 Pins
• P3 .............. Connector 3 screw terminal 5mm 3 Pins
• Others ....... Wires, Power Transformer, Solders, pcb, heat sink, 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. 5 - PCB - 1.5V to 28V, 7.5 Amps Adjustable Symmetric Power Supply using IC LT1083

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!!!

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.

You may be interested in: 

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!!!

Fig. 1 - Symmetrical Power Supply for Power Amplifiers

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.

You may be interested in: 

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:

• 6 x 6.800uF Capacitor
• 15A rectifier bridge
  
  

Configuration 2:

• 6 x 6.800uF Capacitor
• 25A rectifier bridge
  
  

Configuration 3: