8 - Protecting L.E.D.'s

 

L.E.D. + Resistor Circuit Diagram

 

Component
Real World Images
Circuit
Symbol

Light Emitting Diode
L.E.D.

Battery
Fixed Type Resistor

 

Light Emitting Diodes (L.E.D's.) have recently taken the place of the filament light bulbs shown in the previous sections. L.E.D's last longer, create less heat and being more efficient are less expensive to use.

However, it is important for L.E.D's to be protected in a circuit. This is because many do not follow Ohm's Law and do not take the current they need. This leaves them at risk of allowing too much current to flow through them.

In the circuit diagram above, you can see protection is achieved by adding a small fixed resistor in series with the L.E.D. The resistor protects by appropriately limiting the battery's current in the circuit.

Points to Note

The + side of the battery must connect to the Anode (or + side) of the L.E.D.

We need to select the right value of resistor, so different types of LED can be safely used with different battery voltages.

The "LED Resistor" link at the top of the screen provides further reading on this...