These 1.5V white LED flasher circuit uses a handful of electronic parts to make a white LED blink on and off repeatedly.
It is a simple project that is perfect for beginners in electronics, letting you have fun with flashing lights without needing a complicated setup.
Circuit Working:
Parts List:
| Category | Description | Quantity |
|---|---|---|
| Resistors | 2.7k, 330Ω, 47Ω (1/4 watt each) | 1 each |
| Capacitors | Ceramic 10nF | 1 |
| Electrolytic 100µF 25V | 1 | |
| Semiconductors | Transistors BC338, BC547 | 1 each |
| Diode 1N4148 | 1 | |
| White LED 5mm 20mA | 1 | |
| Ferrite Coils | 2.6mm wide, 6mm long, 60 turns | 1 |
| 2.6mm wide, 6mm long, 40 turns | 1 | |
| Other Components | ON/OFF Switch | 1 |
| Power Source | Battery 1.5V | 1 |
The circuit above is a 1.5V white LED flasher circuit that uses a transistor to create a blinking effect.
Here is the circuit working process:
When the switch is turned on, current flows from the battery through resistor R1 and into the base of transistor Q1.
This turns on transistor Q1, which allow current to flow through the collector and emitter of Q1 and through the inductor.
As the current flows through the inductor it build up a magnetic field.
A tiny ferrite core 2.6mm wide and 6mm long is used to wind the transformer coil.
When the switch is turned off the current flow through the inductor is interrupted.
However, the inductor tries to resist this change in current by inducing a voltage spike.
This voltage spike is applied to the base of transistor Q2 through capacitor C1 and diode 1N4148.
The voltage spike turns on transistor Q2 which allows current to flow through the LED causing it to flash.
Capacitor C2 helps to control the timing of the flashing LED.
The value of the components in the circuit will determine the frequency of the flashing LED.
You can experiment with different values to change the flash rate.
Please note the following information while experimenting with this circuit.
- Make sure that the transistors and LED are rated for the voltage and current that will be flowing through them.
- Pay attention to the polarity of the components especially the LED and the diode.
- Use a breadboard to prototype the circuit before soldering the components together.
Formulas:
This circuit is energy efficient and runs at a low voltage of 1.5V, making it appropriate for battery powered applications.
Below is a general formula for a LED flasher circuit.
The frequency oscillator f:
The time constant of the RC network made up of R1 and C1 mostly controls the oscillation frequency in the circuit.
The following is the approximate formula for oscillation frequency:
f = 1 / 2.2* R1 * C1
where,
- In ohms, R1 represents resistance, and
- In farads F, C1 represents capacitance.
Reactive Capacitivity:
The feedback loop and, consequently, the oscillation stability are impacted by the reactance XC of capacitor C2 at the oscillation frequency.
It is provided by:
XC = 1 / 2πfC2
where,
- C2 is the capacitance in farads and f is the oscillation frequency.
Gaining a grasp of these crucial connections and factors will help you create and modify the 1.5V white LED flasher circuit efficiently.
The oscillator must be configured appropriately, the transistor must function properly, and the feedback must be balanced using capacitive and inductive components for the circuit to function.
How to Build:
To build a Simple 1.5V White LED Flasher Circuit follow the below mentioned steps for connections:
- Connect the collector of transistor Q1 to positive supply.
- Connect the base of transistor Q1 ferrite coil and resistor R1.
- Connect the emitter of transistor Q1 to ground.
- Connect the collector of transistor Q2 to ground through white LED and resistor R3.
- The base of transistor Q2 is left unconnected.
- Connect emitter of transistor Q2 to positive supply through a resistor R2.
- Connect capacitor C2 through emitter of transistor Q2 to ground.
- Connect diode 1N4148 through ferrite coil to positive supply.
- Connect ON/OFF switch to positive supply of 1.5V battery.
Note:
- Be careful when working with electronic circuits, as there is a risk of shock.
Conclusion:
To conclude, a 1.5V white LED flasher circuit is a fun and educational project that allows you to create a blinking LED using a single AA battery.
While it requires overcoming voltage limitations for the LED and implementing a flashing mechanism, these circuits are relatively simple to build and offer a low power solution for blinking lights in various application.