12V

12V was a voltage standard for LEGO Trains sets from 1969 until 1991 and complemented the older battery powered 4.5V standard. The power of the 12V system came from a mains powered DC Transformer delivered by add-on center conductor rails. TECHNIC also offered a 12V motor in the form of 880 12 Volt Motor which ran from 1977 to 1982.
In order to reach the newer 12V standard, the older – but still co-existing – 4.5V Trains system could be upgraded by using different 12V Trains accessories.
The second generation "gray" system introduced in 1980 brought much more functionality and expansion options, with the system able to support functioning lights inside the trains, remote controlled signals, power operated points/switches, decouplers and level crossings.
No further 12V sets were released after 1986, and the 12V powered trains were replaced by 9V trains in 1991. Spare parts and accessories for the 12V system (but not complete sets) remained on sale via LEGO mail order service until 1993. 
== 12V Powered Sets ==
===Trains===
* 722 12V Electric Train with 2 Wagons (1970)
* 723 Diesel Locomotive (1970)
* 724 12v Diesel Locomotive with Crane Wagon and Tipper Wagon (1972)
* 725 Freight Train Set (1974)
* 726 Western Train (1976)
* 727 Locomotive (1977)
* 7725 Electric Passenger Train Set (1981)
* 7727 Freight Steam Train Set (1983)
* 7730 Electric Goods Train Set (1980)
* 7735 Freight Train Set (1985)
* 7740 Inter-City Passenger Train Set (1980)
* 7745 High-Speed City Express Passenger Train Set (1985)
* 7750 Steam Engine with Tender (1980)
* 7755 Diesel Heavy Shunting Locomotive (1983)
* 7760 Diesel Shunter Locomotive (1980)
=== Trains Accessories ===
* 703 12V Replacement Motor (1970)
* 704 12V Sleeper (Track) Contacts (1970)
* 705 Motor Bushings (1970)
* 706 Rail Contact Wires (1970)
* 708 2m Extension Cord for Points (1970)
* 741 12 V Transformer (1974)
* 742 12v Transformer - for 100V Mains (1970) - 12V transformer for North America
* 753 Automatic Right Electric Switch (1969)
* 754 Automatic Left Electric Switch (1969)
* 755 Left and Right Points (1974) - left and right switches
* 756 electric crossing (1974)
* 7823 Container Crane Depot (1986) - Container Loading Crane
* 7834 Level Crossing (1980)
* 7839 Car Transport Depot (1986) - Car Carrier Platform
* 7854 Straight Electric Rails (1980) - 8 Straight Electric Rails Grey 12V
* 7855 Curved Electric Rails (1980) - 8 Curved Electric Rails Grey 12V
* 7856 Electric Points (1980) - Left and Right Manual Points with Electric Rails Grey 12V
* 7857 Electric Crossing (1980) - Crossing, Electric Rails Grey 12V
* 7858 Remote Controlled Points Right 12 V (1980)
* 7859 Remote Controlled Points Left 12 V (1980)
* 7860 Remote Controlled Signal (1980) - Remote Controlled Signal 12V
* 7861 Lighting Set Electric 12 V (1980)
* 7862 Remote Controlled Decoupling (1981) - Remote Controlled Decoupling and Signal 12V
* 7863 Remote Controlled Point Motor 12 V (1980)
* 7864 Transformer / Speed Controller 12 V (1980)
* 7865 Motor Replacement Unit for Battery or Motor-Less Trains 12 V (1980)
* 7866 Remote Controlled Road Crossing 12 V (1983) - Level Crossing with Electric Gates
* 7867 4 Lighting Standards Electric 12 V (1983)
=== Service Packs ===
* 11 Locomotive Traction Tires (1977)
* 12 Wheel Bearings for Locomotives (1977)
* 19 Locomotive Piston Assemblies (1977)
* 1111 Rubber Rims for Locomotive Wheels (1977)
* 1112 Train Sliding Wheel Blocks (1977)
* 1119 Locomotive Piston Assemblies (1977)
* 1138 Replacement Rubber Wheel Treads for Trains (1981)
* 5069 2 Lighting Bricks 12 V (1987)
* 5073 Light Transmitting Elements (1987)
* 5082 Flashlight Unit 12 V (1989)
* 5084 Lighting Bricks 12 V for Signals (1989)
* 5086 Replacement 12V Motor (1993)
==Complete List==
Category:Themes
Category:Trains
Category:Service Packs
Category:12V