Electronic Circuits

Wednesday, March 16, 2022

How To Make Rechargeable Emergency LED Light Using LM350 IC with PCB

Electronic Circuits Battery Charger , Circuits to Assemble

Fig. 1 - How To Make Rechargeable Emergency LED Light Using LM350 IC with PCB

Crafting a Rechargeable Emergency LED Light with LM350 IC: Step-by-Step Guide with PCB Implementation

You know that night when the power grid collapses and the power goes out, so we need a light to illuminate the darkness.

That's when we realized that we would need some equipment that could light up that darkness...

In this article, we are going to assemble a Rechargeable Automatic Emergency LED Light circuit that when the power goes out, it activates the set of LED lamps automatically using a rechargeable 12V battery.

How the Circuit works

The Automatic Illuminator circuit is divided into three distinct parts:

The first part:

It's pretty obvious, we have the 220Vac or 110Vac voltage coming from the mains, and we need to convert it to 12Vac. For this, we use a 220V/12Vac transformer. The output of the 12Vac transformer, it is connected to a diode bridge to rectify the AC voltage to DC, and the 2200uF capacitor to filter this voltage.

The second part:

It is a 12V battery charging stage, it works simply as a charger, it has a status LED that when charging it stays on, and when charged the LED goes off.

The circuit uses the LM350T voltage regulator. The output current of the LM350 is 3 amps, it is necessary to adjust the output voltage through the trimpot of 4.7K, this voltage must be adjusted according to the battery used.

In some batteries this voltage is 13.8V, in others it is 14.4V, this is always described together in the general battery information.

For those who follow us here on our site, you may have already noticed that the 12V battery charger circuit is very similar to an article that we have already done here on our site, you can check it out by clicking on this link.

12 Volts Automatic Lead Acid Battery Charger Using LM350 IC with PCB

The Third part:

It is a control circuit composed of a BD140 PNP transistor, which works as a drive circuit, when there is power on the grid.

The voltage from the source passes through the 1K base current limiting resistor, and causes the transistor to stay open, keeping the light off, as soon as the voltage is cut off.

The transistor as a switch closes the circuit, slinging the battery to the set of 20 LEDs, turning the light on.

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. 2 - Schematic Diagram Rechargeable Emergency LED Light Using LM350 IC

The Power Transformer

The transformer should have as primary according to your local network, 110Vac or 220Vac. The secondary should be 12V, since when we pass through the rectification, this 12Vac voltage is transformed more or less into 16.9Vdc.

The transformer should have a current of 3 amps, in case you are going to use it with large batteries, such as 7A, 9A, etc…

If you are going to work with smaller batteries, it is up to you to place a transformer proportional to the total power of the LEDs and the battery used. The transformer configuration diagram is shown in Figure 4 below.

Fig. 3 - Schematic Diagram Transformer 110/220Vac to 12Vac 3Amps

Component List

Semiconductors

U1 ........................ LM350 Voltage Regulator
Q1 ........................ BC548 NPN Transistor
Q2 ........................ BD140 PNP Transistor
D1 ........................ KBU4A - 4A Rectifier Bridge
D2 ........................ 1N5408 Diode Rectifier
LED1 to LED20 ... Light Emitter Diode 5mm High Light
LED1 .................... Light Emitter Diode 3mm (general use)

Resistors

R1 ............... 100Ω 1/8w Resistor (brown, black, brown, gold)
R2 ............... 0.5Ω 5W Resistor (green, black, silver, gold)
R3 ............... 470Ω 1/8w Resistor (yellow, violet, brown, gold)
R4 ............... 120Ω 1/8w Resistor (brown, red, brown, gold)
R5 ............... 1kΩ 1/8w Resistor (brown, black, red, gold)
R6 to R10 ... 1Ω 3W Resistor (brown, black, black, gold)
RP1 ............. 4K7Ω Trimmer

Capacitors

C1 ...... 2.200uF - 25V Electrolytic capacitor
C2 ...... 0.33uF - 25V Electrolytic capacitor

Miscellanies

P1, P2 ....... Connector 2 screw terminal 5mm 2 Pins
T1 ............. Transformer Reduction 110/220ac to 12Vac (See Text)
Others ....... Wires, Solders, pcb, heat sink, etc.

PCB - 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. 4 - PCB - Rechargeable Emergency LED Light Using LM350 IC

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

I hope you enjoyed it!!!

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!!!

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

Electronic Circuits Circuits to Assemble , Electronic Circuits

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

Versatile Power at Your Fingertips: Build an Adjustable 1.5V to 28V, 7.5 Amps Symmetric Power Supply with IC LT1083 and 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:

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.