An 1.5V white LED driver circuit acts like a translator for electricity.
It takes raw power from your source i.e battery and converts it to the exact current and voltage an LED needs to shine safely and brightly.
Without which the LED could be dim or burnt out.
Circuit Working:
Parts List:
| Category | Description | Quantity |
|---|---|---|
| Resistors | 33k, 470Ω (1/4 watt each) | 1 each |
| Capacitor | Ceramic 1nF | 1 |
| Semiconductors | Transistors BC557, BC338 | 1 each |
| LED | White LED 5mm, 20mA | 1 |
| Inductor | Iron core coil slug (2.6mm diameter, 6mm long, 0.25mm wire) | 1 |
| Other Components | ON/OFF Switch | 1 |
| Power Source | 1.5V Battery | 1 |
The circuit here is a simple 1.5V white LED driver circuit that uses a transistor to regulate the current to the LED.
This circuit takes a step beyond the basic 1.5V LED drivers by using a unique design to power a super bright white LED.
When the switch is turned on, current flows from the battery positive terminal through resistor R1, biasing the base of transistor Q1 BC557 on.
As Q1 turns on, it allows current to flow from the collector to the emitter through the coil and the white LED.
The 1nF capacitor creates a positive feedback loop.
As the voltage increases the transistors turn on more further amplifying the signal until it reaches its peak.
Then the loop reverses and the transistors turn off completely.
This cycle create the oscillation needed to drive the LED.
This circuit utilizes a 60 turn coil wrapped around a tiny ferrite core having 2.6mm diameter and 6mm long with 0.25mm wire.
This core material helps improve efficiency.
The coil core stores energy when current flows through it.
When the switch is turned off the energy stored in the coil core releases a burst of current to the LED which helps to maintain brightness for a short period.
This design achieves oscillation through a more complex method.
Instead of relying solely on the core coil it uses a 1nF capacitor to provide feedback to a two transistor amplifier.
Note:
If you do not have a ferrite core, the circuit offers alternative option for building the inductor using readily available materials like machine screws or brass ferrules.
Formulas:
Ohms Law formula is used to calculate the resistor value in a simple 1.5V White LED Driver Circuit:
R = V / I
where,
- In ohms Ω, R represents the resistance.
- The voltage expressed in volts is V.
- I is the amps A of current.
The resistor R1 in the 1.5V White LED Driver Circuit may be calculated using this formula.
How to Build:
To build a Simple 1.5V White LED Driver Circuit follow the connections steps mentioned below:
- Connect the collector of transistor Q1 to the base of transistor Q2 through resistor R2.
- Connect the base of transistor Q1 to one end of capacitor C1.
- Connect the emitter of transistor Q1 to positive supply through iron core coil.
- Connect the collector of transistor Q2 one end of capacitor C1.
- Connect the base of transistor Q2 to collector of transistor Q1.
- Connect the emitter of transistor Q2 to ground.
- Connect a white LED from the collector of transistor Q2 to ground.
- Connect a ON/OFF switch to the positive supply of 1.5V battery.
Safety Note:
- Be careful while building this circuit double check component rating and follow proper construction techniques to avoid damaging components.
Conclusion:
To conclude, 1.5V White LED driver circuit by mentioning the current draw achieved at similar brightness levels using different core materials for the inductor.
This showcases the impact of the core selection on efficiency.