LEDs (Light Emitting Diodes) can be wired in several ways, each affecting how they function within a circuit. The two most common methods are wiring in series and wiring in parallel.
Wiring LEDs in Series
- LEDs wired in series are connected end-to-end. This means the negative terminal (cathode) of one LED is connected to the positive terminal (anode) of the next.
- This creates a single path for current to flow through all the LEDs.
- The current remains the same through each LED in a series circuit.
- The voltage is divided among the LEDs. This means the total voltage required to power the series of LEDs is the sum of the forward voltage of each LED.
Example: If you have three LEDs, each with a forward voltage of 2V, you will need a 6V power source (3 LEDs * 2V/LED = 6V) plus any voltage drop needed by a current limiting resistor.
Diagram:
[Power Source +] --> [LED1 -]--[LED1 +] --> [LED2 -]--[LED2 +] --> [LED3 -] --> [Resistor] --> [Power Source -]Wiring LEDs in Parallel
- LEDs wired in parallel are connected side-by-side. This means all the positive terminals (anodes) are connected together, and all the negative terminals (cathodes) are connected together.
- This creates multiple paths for current to flow.
- The voltage remains the same across each LED in a parallel circuit.
- The current is divided among the LEDs. This means the total current required to power the parallel LEDs is the sum of the current required by each LED.
Example: If you have three LEDs, each requiring 20mA, you will need a power source capable of providing at least 60mA (3 LEDs * 20mA/LED = 60mA). A current limiting resistor should still be used to control current to the whole LED set.
Diagram:
[LED1 -]
/
[Resistor]--| [Power Source -]
\
[LED2 -]
/
[Power Source +]--| [Resistor]
\
[LED3 -]Choosing Series vs. Parallel
The choice between series and parallel wiring depends on the specific application and available power source.
| Feature | Series | Parallel |
|---|---|---|
| Current | Constant (same through each LED) | Divided (total current is sum) |
| Voltage | Divided (total voltage is sum) | Constant (same across each LED) |
| LED Failure | One LED failure breaks the entire circuit | One LED failure doesn't affect others |
| Wiring Complexity | Simpler (fewer wires) | More complex (more wires) |
Generally, series wiring is more efficient if the power source voltage is higher than the individual LED forward voltages. Parallel wiring can be useful if the power source voltage is low and each branch is current-limited. However, without proper current limiting for each LED in a parallel circuit, one LED can hog most of the current, leading to burnout.
Importance of Current-Limiting Resistors
Regardless of whether you wire LEDs in series or parallel, it's essential to use current-limiting resistors. LEDs are current-driven devices, and without a resistor, they will draw too much current and burn out almost instantly. The resistor limits the current to a safe level, ensuring the LED's longevity and proper operation.
