Car cigarette lighter
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The automotive cigarette lighter is more properly called a cigar lighter, since it was originally designed as a lighter for cigars—hence its rather large size and unheated center. The device contains a thin coil of nichrome wire, through which very high current (15-20 amps) passes when the device is activated, usually by pushing its handle in. The heating element becomes glowing orange hot in seconds, and the handle pops out. If the lighter is then promptly removed from its socket, it is capable of lighting cigarettes, cigars and tinder (among other things) on fire.
The lighter's socket doubles as a 12 volt DC power outlet that can be used for many purposes; for example, electric razors, portable spotlights, laptop computers, mobile phones, PDAs, USB adapters, digital audio players, or even thermoelectric coolers can be connected to a lighter socket and be powered or have their batteries recharged. For devices that only run on regular line voltage, an inverter will convert to alternating current, and transform it up to 120 or 240 volts AC. (Inverters have become so popular that some larger vehicles (minivans and pickup trucks) come with them built-in.)
In some newer cars, due to the decreasing popularity of smoking and the popularity of in-car electronics, the lighter has been replaced by a 12-volt power outlet that does not actually function to light cigarettes. Some minivans come with several lighter sockets, allowing various devices to be used at different seats.
Technical details
These sockets were not originally designed to provide power, and are not an ideal power connector for several reasons, notably the fact that three sizes exist (one for 6 VDC and two for 12 VDC) and the mating of the different sized 12 VDC plugs and jacks is problematic. They can be unreliable and the power connections they provide are limited to low current, but they are ubiquitous. Plugs often include a pilot light to indicate a connection has been made. The sockets and mating plugs are officially defined in the [ANSI/SAE J563] specification.For the 12-volt systems, the "contact point," which is the center part of the plug when viewed end-on, carries the positive voltage, whereas the "can" part, which is the outer part of the connector, carries the negative voltage (which is the "ground" connection for most American automobiles, which have a negative ground electrical system).
6 volt cigar lighter receptacle and plug
- Receptacle inside diameter: 21.34mm to 21.46mm
- Plug body diameter: 21.08mm to 21.23mm
12 volt cigar lighter receptacle and plug, size A
- Receptacle inside diameter: 20.93mm to 21.01mm
- Plug body diameter: 20.73mm to 20.88mm
- Most often used in American automobiles.
12 volt cigar lighter receptacle and plug, size B
- Receptacle inside diameter: 21.41mm to 21.51mm
- Plug body diameter: 21.13mm to 21.33mm
- Most often used in European automobiles, and sometimes as a second socket in American automobiles expressly for DC power connections.
References
See [Standards And Specs For In-Seat Power On Aircraft Still In The Clouds] for an Electronic Design article on the topic of automotive and airline DC power connections. Alternate location, with illustrations: [link]
See also
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