LED flashlight circuit or LED torch with 1.5V battery

Let’s create an LED flashlight circuit or what some people called an LED torch circuit diagram. This high power LED flashlight circuit look like a torch by use on 1.5V battery only so it can be used. Since small so Easy to carry in various places. And also very bright as well.

Simplest High Power LED Flashlight

We should start with the easy things first. This is the simplest high-power LED flashlight circuit. My son made it on March 17, 2017. It has 24 super bright LEDs for display, 3 AA batteries, and a resistor to limit current. So, this circuit is easy and cheap.

How does it work

We use the white super bright LED. This type of LED is a very bright, direct beam, suitable for building a flashlight. It requires the voltage about 3.3V at 20mA current We test it as simple circuit diagram below.

one LED flashlight with 3.6V batt
Simple one LED flashlight circuit with 3.6V battery

We use 24 white super bright LEDs to make flashlight as the circuit diagram below. They are connected together in parallel. The each led need to use the voltage about 3.3V at 20mA current. It makes LEDs uniform high brightness, but use all current are 0.4A to 0.6A.

Simple High Power LED Flashlight circuit
Simple High power LED flashlight circuit diagram with 3.6V battery

The 1 ohms resistor is used for limiting safe current to LEDs. In this circuit, we use a 3x AA 1.2V Ni-HM (Nickel-metal hydride) battery. So, their total voltage is 3.6V.

In the circuit above, my daughter (beginner) said it looked hard to understand. Some people might think like this. So we added an illustration that is easier to understand.

easier 24 high power LED flashlight diagram
Look at the 24 high power LED flashlight that is easier to understand.

Recycling free white SMD LED from e-waste

Let’s build this project

We assemble the LEDs and resistor on universal PCB Board. We use a 3 x AA battery holder with a built-in on-off switch. So, making this circuit easier.

testing simple high power flashlight

Finally, solder all parts on PCB and wiring.
We measure all current active approximately 0.5A but very very bright.

Simple High power LED flashlight finished

The end, We made a Simple High power LED flashlight successfully.

Recommended: 1.5V 4 LEDs Flasher circuit using transistors

Simple 1.5V LED flashlight circuit

At present, my daughter will come to modify the same circuit that my brother used to create. By she said the circuit that my brother built, it uses high current and use up to 3 batteries.

In the past, it was appropriate Because the battery is 700mAh. But at present we use a battery that has a capacity of 2400mAh. Because 700mAh batteries are rare. So we modified this circuit to use less current. And it’s better to use a single battery.

My daughter wants to build the simplest circuit or use fewer components but it works.

Read also: DIY Flashing Bicycle LED Taillight Circuit

High Power LED flashlight circuit

The technical information

Power supply : one 1.5V AA battery.
Maximum current used 200mA
Uses 6 white LED.
Small size PCB.

How it works

As usual, the LED light when a voltage is 1.8V or 2V,
We need a way to increase the voltage to rise, by the switching supply mode in step-up DC to DC converter circuit.

High power LED flashlight circuit, 6 LED for 1.5V AA battery

Figure 1 Circuit diagram of High power 6 LED Flashlight for 1.5V AA battery.

As Figure 1 is Circuit diagram of this project. By operation of the circuit is determined by Coil and C2. Which will serve as the production cycle frequency. The LC Frequency circuit with capacitors and capacitor alternately, cause frequency.

When we apply power supply voltage to circuit, the transistor TR1 will working. Then TR2 will work as well. In the meantime, C2 will charge store current. So all LEDs will go out. But when fully charging, TR1 will stop working result C2 discharge to all LEDs glow.

Learn: How to use 555 timer circuits

Since the charging and discharging very fast, cause we see them same still brightness. The capacitor-C1 will be filter the current to smooth.

How to builds.

Real PCB of high power 6 led flashlight for aa battery

This project is small and a few part so we can use a perforated board. Or use real PCB as Figure 2. Then assemple all parts on PCB and wiring as Figure 3.

Figure 2 the real PCB of this project.

Components layout and circuit assembling

Figure 3 the components layout.

Coil is about 100uH

The L1-inductor is 100uH as Figure 4 I measure it show you. And you can use any type that look like it.

Figure 4 Coil is about 100uH.

High power 6 LED Flashlight for 1.5V AA battery

Figure 5 The High power 6 LED Flashlight projects for 1.5V AA battery.

When completed circuit assembly Supply voltage range of 1.5V to the circuit.
Then slide the switch to position ON. The All LEDs will lit, the circuit is ready for use.
As Video below.

I want to see wavefrom across LEDs (all in parallel) through an oscilloscope panel.
We will see that high amplitupe about 3Vp-p it cause LEDs glow.

Note: AA battery we should is kind of alkali house. Because high performance

The parts list
Resistors 0.25watts
R1: 10K
R2: 6.8K
R3: 100 ohms

Electrolytic capacitors
C1: 220uF 16V

Ceramic Capacitors
C2: 680pF 50V

Inductors coil
L1: 100uH Please how to build it here
Q1: CS9012, 0.8A 40V PNP Transistors.
Q2-Q4: CS9013, 0.8A 40V NPN Transistors.

PCB, 1.5V AA Battery, etc.

Other led flashlight circuits

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38 thoughts on “LED flashlight circuit or LED torch with 1.5V battery”

  1. Thanks for reply sir. The link you give me that I can Modify the toroidal coil.
    But In order to make any inductor accurately then formula is needed. If you have please share.

  2. hello sir,
    how many coli of wire need to make 100uh inductor..i mean how many times i rotate the wire to the coli because i don’t the meter to mesure it..

  3. @sk sahabaj.
    I am sorry to you. Please check all parts and wiring circuits again.
    This circuit works.
    And voltage output is 1.5V same you read on meter but I look at scope is dc pulse 3Vp-p.

  4. i wake up in early morning and start doing the circuit from start i made this on a breadbord i made a new inductor with new wire and ferrite core and then recreate the circuit again and NOW THE CIRCUIT WAS WORKING.Yes i have done misstake but now its working now am so happy..

  5. Hello Mr:

    i really faced a problem, i am designning one project

    useing one 18650 battery to support one resistance, so the resistance would heating

    i am try to up the output wattage to 30wattage or 100wattage__the resistence wattage ,

    need to converter the output voltage to 10V or 12V ? the output mA current need to converter 5A ?

    if you can give some advice or i need to choose some ic ?


  6. Dear sirs, hello,

    I am trying to buy components for the high power 6 LED flash light,
    and I never have the good part number.

    Con somebody send to me the complete board ?

    Many thanks, best regards,
    Paul Baroud

  7. Hi I’ve just finished building 6 led torch +1AA battery on a breadboard . Brilliant circuit I will be soldering this one.
    Thanks again for an excellent resource.

  8. #Simple high power LED flashlight circuit

    Nice Job On This Project!!! Many Thanks(For The 1000th Time) From MROHM1970

  9. Very Fine Circuits and Material. As a non-Electrical/Electronics Candidate i have a simple question of “How to find the Voltage Requirement of a/any load(May be a LED/Fan/Motor etc)”?

  10. Hello sir….
    i want to make a simple torch using an 18650 battery cell with 3v 3watt flash led.
    i put thermal paste between heatsink and led but still it becpmes too hot that it burns what should i do

    • The easiest way is to install a large heatsink as it draws about 1A of current.

      Or a more difficult method is to try using a pulse generator, resulting in a lower average power to the LED.

      But the brightness of the LED is also reduced, which my daughter and I have tried.

      or there may be other methods which we will try in the future.


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