How many LEDs can I drive in series?

It depends on your supply voltage. You have to be able to overcome the cumulative forward voltage of the series combination in order to get them lit. As an example, ...
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How do I drive LEDs from alternating current?

Without getting into a detailed circuit design, there are a couple things to think about when using an AC source. Diodes will conduct only when forward biased, so with AC ...
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How do I replace an LED with a brighter LED?

Generally, improvements in brightness have come about a result in improvements in manufacturing processes and materials. The electrical characteristics of the brighter LEDs don’t differ drastically from the older generation ...
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How are infrared LEDs different?

There are a couple key differences in the electrical characteristics of infrared LEDs versus visible light LEDs. Infrared LEDs have a lower forward voltage, and a higher rated current compared ...
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What is thermal runaway?

When a junction gets warmer, the current through it at a given voltage will increase. The increased current in turn heats the junction further, and the problem gets worse. Eventually, ...
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What kind of resistor should I use with an LED?

The important considerations when you’re selecting a current-limiting resistor are the value in Ohms and the power rating in Watts. The LED resistor calculator can help you determine both values ...
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What is the useful life of LEDs?

When you buy a package of light bulbs, you’ll see a number on the box that says something like “Life: 1125 hours.” This is defined as the time it takes ...
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Are LEDs inherently directional?

No. One way for a manufacturer to boost the luminous intensity spec (usually given in candelas or millicandelas) is to focus the beam more tightly. The same light flux, focused ...
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What happens if I overdrive an LED?

A typical indicator LED will have a spec that represents a typical point along the operating curve. That would look something like “3.3V @ 20mA typical.” Driving this LED above ...
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Can LEDs be dimmed?

It’s useful to think of an LED as a current-driven device. The light output is proportional to the drive current over a decent range. But things go a bit odd ...
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What are the electrical characteristics of LEDs?

It’s useful to think about two main types of LEDs—the familiar indicator LEDs that come in 5mm and 3mm epoxy packages, and “illumination-grade” LEDs, which are high-output devices, designed for ...
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What makes an LED such a good colored light source?

If you want a colored light, LEDs can’t be beat for efficiency. The process that gives off the light makes light of a certain wavelength, which is a function of ...
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