We use cookies and similar tools that are necessary to enable you to make purchases, improve your shopping experience and provide our services, which is also described in our Privacy Policy. We also use these cookies to track how customers use our services (for example, by measuring website traffic) so that we can make improvements. This includes the use of first- and third-party cookies that store or access standard device information such as a unique identifier. Third-party vendors use cookies to serve personalized ads, measure their effectiveness, generate audience insights, and develop and improve products. Use the "only technically necessary cookies" button to reject these cookies. Click on "individual cookie settings" to reject these cookies, make more detailed settings or learn more. You can change your selection at any time by changing the cookie settings in the privacy settings. To learn more about how and for what purposes personal data (e.g., order history) is used, please read our privacy policy.
  1. Mainpage
  2. LED Basics

LED Basics

General:
A LED (light-emitting diode) is a semiconductor light source.  A LED glow when current flows in the conducting direction.

Design:
As diode the LED have two circuit points minimum, anode (+) and cathode (-). At the most LEDs, anode and cathode are labelled. The shorter conductor is the cathode at different connection wires. Guideline: "Long is always positive".

Zeichnung 5mm LED

Typical parts of a 5mm LED composed of body, anode and cathode.

blaue 5 mm LED

Characteristics:
LEDs aren't thermal spotlights. The emitting light corresponds to a limited spectral range. Until a few years ago it was not possible to produce all colours of the visible light by means of LEDs. There are the blue LEDs only for some years. With the development of blue LEDs, it was at the first time possible to develop LEDs which glow white. For this, blue LEDs are provided with a changing hue layer.

The lighting current is proportional to the operational current which is depending on temperature. The typical solution is to use Constant Current Sources, at most in the form of a series resistor.

Because of the physical qualities the LEDs are subject of a natural ageing, also called degradation. The life time of LEDs depends on the semiconductor materials and the operating conditions. High temperatures drastically reduce the life time of a LED. Often an adequate heat sink is needed for a long life.