LED calculator for single LEDs. Constant current source with LM317. Light Emitting Diodes (LEDs) Colour | Sizes and shapes | Resistor value | LEDs in series | LED data | Flashing | Displays Also see: Lamps Example LED: Circuit symbol: Function LEDs emit light when an electric current passes through them. Connecting and soldering LEDs must be connected the correct way round, the diagram may be labelled a or + for anode and k or - for cathode (yes, it really is k, not c, for cathode!). LEDs can be damaged by heat when soldering, but the risk is small unless you are very slow.
Testing an LED Never connect an LED directly to a battery or power supply! LEDs must have a resistor in series to limit the current to a safe value, for quick testing purposes a 1k resistor is suitable for most LEDs if your supply voltage is 12V or less. For an accurate value please see Calculating an LED resistor value below. Colours of LEDs LEDs are available in red, orange, amber, yellow, green, blue and white. Tri-colour LEDs The diagram shows the construction of a tri-colour LED.
Bi-colour LEDs ). For example. Constant current source with LM317. LED calculator for single LEDs. LED calculator for single LEDs. Light Emitting Diodes (LEDs)