Led which lead is ground

A red LED uses the least amount of voltage to turn on, about 1. This current is the same amount that flows to the LED but the voltage across the resistor is different because the LED has a turn on voltage which you subtract from the supply voltage:. All about LEDs. Skip to main content. Using the Pins Digital Input. There are a variety of wire connectors for different types of wires so it is critical that your connectors are made for the wire you are using and securely fastened.

A common mistake people make when wiring LED lighting products is trying to simplify the installation by jamming 10 wires into a wire nut or phoenix connector.

Instead of doing this it is better to use multiple wire splitters, terminal blocks, or solder wires together to split your wires, rather than try and overload a wire connector which can be a serious fire hazard. When installing larger LED installations or installations with a lot of wire running to multiple locations it is a must to wire your lights in parallel to the controller or power supply to reduce voltage drop. Think of a parallel connection as your LED lights running independently back to the power source, or run a home run wire to your power supply and splice into that wire at your different wiring locations.

Test with a multimeter to check for voltage drop. When using solid wire in a low voltage system you will notice, at best, that you will have three small contact areas between the solid wire and the device connection when using a typical screw down terminal.

This also applies to power distribution blocks or wire nuts where you have only two contact areas, that can cause a heating connection. When your wires are frayed and going in all directions you are at risk of multiple wiring issues.

First of all you will notice voltage drop if only a few pairs of your stranded wire are making electrical contact, secondly you are putting your installation at risk for an electrical short and potential fire hazard. When wiring your LED Lighting project it is very important to not leave any of your wire splices exposed. Leaving bare wire splices exposed puts your installation at risk for an electrical short and potential fire hazard.

Always use proper wire connectors and never leave bare wire splices exposed. Overloading wire connectors is the most common mistake when installing LED lighting products. When there are too many wires in a connector that is designed for a single wire this can cause serious fire hazard issues if a short occurs or the wires begin to arc. It can also cause voltage drop issues if some wires have a more secure connection than others. What people don't realize is that each little LED and it's components takes a bit of voltage away from the next in a series.

So the longer you run your LED lights in a series the more voltage drop that is going to occur and the less even your lighting will be. If you are installing lights over 20ft or in multiple locations always use parallel connections. How to Solder White Strips? How to Solder 2 Strips?

Neon Flex Strip Lights. Applying a negative voltage for an extended period to an electrolytic capacitor results in a briefly exciting, but catastrophic, failure. They'll make a pop , and the top of the cap will either swell or burst open. From then on the cap will be as good as dead, acting like a short circuit. Getting polarity right in your circuit all starts and ends with getting the power supply connected correctly. Whether you're project's getting power from a wall-wart or a LiPo battery , it's critical to make sure you don't accidently connect them backwards and apply - 9V or - 4.

Anyone that's ever replaced batteries knows how to find their polarity. Other times it might be red wire for positive and a black wire for negative. An assortment of batteries. Each has some way to represent positive or negative terminals. Power supplies usually have a standardized connector , which should usually have polarity itself. Other connectors, like a JST , are keyed so you just can't connect them backwards. For extra protection against reversing power supply polarity, you can add reverse polarity protection using a diode, or a MOSFET.

These traditionally three-terminal, polarized components are lumped together because they share similar package types. To find which pin is which, look for the flat edge on the TO package or the metal heatsink on the TO, and match that up to the pin-out in the datasheet.

Above, a 2N transistor in a TO package, note the curved and straight edges. This is just the tip of the polarized-component iceberg.

Even non-polarized components, like resistors , can come in polarized packages. A resistor pack -- a grouping of five-or-so pre-arranged resistors -- is one such example.

A polarized resistor pack. The dot represents the first, common pin. Fortunately, every polarized component should have some way to inform you which pin is which. Be sure to always read the datasheets , and check the case for dots or other markers. Now that you know what polarity is, and how to identify it, why not check out some of these related tutorials:. See our Engineering Essentials page for a full list of cornerstone topics surrounding electrical engineering.

Take me there! Need Help? Mountain Time: Shopping Cart 0 items. Product Menu. Today's Deals Forum Desktop Site. All Categories. Development Single Board Comp. Home Tutorials Polarity Polarity. Contributors: jimblom. What is Polarity? Every electrical project starts with a circuit.

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