Simple Circuit for high power LED

In summary: In this circuit, the LM317 ensures the LED is always bright, regardless of the battery voltage. You might want to try using a size-D or lantern battery to see if that'll work.
  • #1
selseg
32
0
What simple circuit that I can design for a 3V high power LED with max current 0.8 amps , I think the component names would help me , I would like to power it on 4.5 to 9 V batteries .Preferably lower voltages. Thanks
 
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  • #2
Connect the 9v battery to the led in series with a (9-3)/.8 Ohm resistor.

On a 4.5v battery use a (4.5-3)/.8 ohm resistor.
 
  • #3
Antiphon said:
Connect the 9v battery to the led in series with a (9-3)/.8 Ohm resistor.

On a 4.5v battery use a (4.5-3)/.8 ohm resistor.

Just make sure the resistor has suitable power rating - in the above scenario, the resistor is dropping 6 volts at 0.8A, which is 4.8 watts. I'd use at least a 10 watt resistor in that case, and that is going to be a LOT of heat... it would need mounted on a pretty beefy heatsink. The LED will need mounted on a big heatsink too.

If the OP can do it, it would be better to have more LED's in series rather than burning all that power as heat, or if you want to get more advanced, a buck switching regulator will get you into the 90%+ efficiency range and make the battery last 3 times longer and massively reduce the heat output.
 
  • #5
These are voltage regulator ICs that ensure the LED is constant brightness even as the battery voltage drops lower.
 
Last edited by a moderator:
  • #6
You may want some size-D or lantern batteries for something that draws this much current. (3) size D alkalines have a nominal voltage of 4.5. That might get you there without wasting too much of your power as heat.
 
  • #7
selseg said:
Thank you very much , I checked from the link below earlier on . Why do they include the LM317 in that circuit ? in another circuit i found online , they used l7805. Why do they include these ics and capacitor ?
http://www.instructables.com/id/Super-simple-high-power-LED-driver/?ALLSTEPS
They're using voltage regulator chips in a "constant current" configuration.
 

1. What is a simple circuit for high power LED?

A simple circuit for high power LED is a basic electrical circuit that connects a high power LED to a power source, such as a battery or power supply, and a resistor to control the flow of electricity. This circuit allows the LED to emit a bright and powerful light.

2. What components are needed for a simple circuit for high power LED?

The main components needed for a simple circuit for high power LED are a high power LED, a power source (battery or power supply), and a resistor. Optional components may include switches and capacitors for added functionality.

3. How do I calculate the resistor value for a simple circuit for high power LED?

To calculate the resistor value for a simple circuit for high power LED, you will need to know the forward voltage of the LED and the desired current. You can use Ohm's law (V=IR) to calculate the resistor value, or use an online LED resistor calculator for more accurate results.

4. Can I use a regular LED in a simple circuit for high power LED?

No, a regular LED is not suitable for use in a high power LED circuit. High power LEDs have a higher forward voltage and current rating, and a regular LED may not be able to handle the power and may burn out. It is important to use a high power LED specifically designed for high power circuits.

5. How can I make a simple circuit for high power LED more energy efficient?

To make a simple circuit for high power LED more energy efficient, you can use a pulse width modulation (PWM) dimmer circuit. This circuit rapidly turns the LED on and off, reducing the average amount of power used and making the LED appear dimmer while still emitting a bright light. Additionally, using a higher efficiency power source and selecting a more efficient LED can also help improve energy efficiency.

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