Class 4 article

9V (later marketed as the Electric System or the 9V-powersystem, depending on country) was a voltage standard for electrical components (e.g. motors, lights) in many LEGO sets. It first appeared in 1985 in the Light & Sound series of Town and Space models that featured flashing lights and sirens, and was later expanded to the Monorail sets.

TECHNIC also moved over to the 9V system in 1990, with Trains making the change the following year.

The power came from a battery box with one 9V PP3 type battery (e.g. or later with 6x 1.5V batteries (TECHNIC, Basic). The 9V system sought to address the major weakness with the preceding 4.5V and 12V systems which was the pinned plug connectors that were prone to coming loose or the wires that would eventually fracture and fail after heavy use. The new system used special bricks that contained conductive elements built into the studs which were connected more positively and were more reliable over long periods of use. Wired connections were still used whenever power had to be transmitted through awkward routes, but the terminations used the conductive brick connectors in place of the pinned plugs.

The Trains theme was the only application of 9V that was powered by a mains DC Transformer and special metal conducting rails for 9V Trains (without any add-on center conductor rails that were used by the earlier 12V Trains system). Controversially however the 9V Trains system lost most of the accessories of the 12V system such as remote controlled signals, points and lights.

Mindstorms used the 9V system until the release of Mindstorms NXT in 2006, which was backwards compatible with the 9V standard with use of 8528 Converter Cables for Mindstorms NXT.

The 9V standard was retired in 2009 and replaced with the Power Functions system, which used the same voltage and was backwards compatible with the 9V standard with use of 8871 Power Functions Extension Wire 20” and 8886 Power Functions Extension Wire.

9V Components[]

Wires & Adaptors[]

Image#SetNumber of piecesMinifiguresPriceRelease
5120-15120Polarity Reversal Switch for 8082 (9V)2$5.501993
50415041Space Track Connector Lead 9V1 1988
970041-128 MM Connecting Leads970041128 MM Connecting Leads3$9.702002
No image98979 V Connecting Leads3 1998
No image98989 V Long Connecting Leads2 1996
5111 Motor Wire51119V Motor Wire, 128cm1$3.991990
10078-Train Connection Wire10078Train Connection Wire1 2003
85288528Converter Cables for Mindstorms NXT3 2006
8871-0000-xx-12-18871Power Functions Extension Wire 20”1$3.99 / €4.692009
8886-0000-xx-12-18886Power Functions Extension Wire1$2.992008

Power Sources[]

Image#SetNumber of piecesMinifiguresPriceRelease
No image9753TECHNIC Control Center15 1993
4548 Electric Train Speed Regulator4548Transformer and Speed Regulator3$42.001992
51155115Technic Battery Box 9V1$11.001991
No image98319 V Battery Box with Switch1 1994
5293-15293Battery Box - Basic and TECHNIC1$12.251996
50385038Battery Box 9V Electric System1 1988
5391-153919V Battery Box1$5.001997
Solar-Cell9912LEGO Solar Cell1$44.951999
Lego 97099709RCX Programmable LEGO Brick1$109.991998


Image#SetNumber of piecesMinifiguresPriceRelease
501150119V Basic Motor1$27.001993
50405040Monorail 9V Motor for Space Track1 1988
51145114Technic Motor 9V1$16.001991
53005300Train Motor 9V3 1991
10153101539V Train Motor3$25.002002
8866-0000-xx-12-18866Train Motor7$10.99 / €12.992009
5225-15225TECHNIC Geared Motor1$15.751998

Lights & Sounds[]

Image#SetNumber of piecesMinifiguresPriceRelease
5307-15307Head Light Brick3 1992
970005-9-Volt 1 x 2 Lamp Brick9700059-Volt 1 x 2 Lamp Brick2 2002
0005-1 x 2 Lamp Brick 9V00051x2 Lamp Brick, 9V2$10.002008
846-box846Lighting Set, 9V39$17.991992
37483748Light Unit for Train4$9.992001
50335033Light and Sound 1 x 4 Lighting Brick and 4 Colour Globes5$5.501987
5034-1-05034Light and Sound 1 x 2 Lighting Brick and 4 Colour Globes5 1987
5308-15308Headlight Bricks3 1994
5310-15310Light Brick Conductor (9 V)4 1996
11721172Replacement Light & Sound 1x2 Lighting Brick with Coloured Globes5 1986
5034-15034Replacement Light & Sound 1x2 Lighting Brick with Coloured Globes5 1987


Image#SetNumber of piecesMinifiguresPriceRelease
9911-19911Touch Sensor and Leads3$12.002004
97569756Rotation Sensor1  
Lego 97559755Temperature Sensor1 1999
9757-19757Touch Sensor2 1999
97589758Light Sensor1 1999
98889888Touch Sensor1 2002
TS9889-19889Temperature Sensor1$25.002004

Train Tracks[]

Image#SetNumber of piecesMinifiguresPriceRelease
4515 Straight Tracks4515Straight Rails8$13.251991
4520 Curved Tracks4520Curved Rails8$13.251991
4531 Switching Rails4531Manual Points with Track6$28.001991
4519-14519Rail Crossing1$10.001999
2159-121599V Train Track Starter Collection24$29.992006
4206-142069V Train Switching Track Collection27$44.992006

Combination Sets[]

Image#SetNumber of piecesMinifiguresPriceRelease
9203-1-09203Deluxe Lighting Kit  1993
624 Box624Basic Motor, 9V27$26.001996
8720-187209V Motor Set57$35.991990
0845-1845Battery Motor, 9V27 1992
91659615Motor Add-On for Simple Mechanisms3$31.991997
Lego-silnik-8287 50948287Motor Box93$29.992006
8735-18735Motor Set, 9 volt60$39.991997
K4548-1K45489-V Train Accessory Collection22$96.972007

9V Powered Sets[]


Image#SetNumber of piecesMinifiguresPriceRelease
0735-1735Basic Building Set537 1990
4223 brickset4223Basic Building Set546 1998


Image#SetNumber of piecesMinifiguresPriceRelease
6399 Airport Shuttle6399Airport Shuttle7439 1990
6430 Box6430Night Patroller140Police Officer 1991
6440 Jetport Fire Squad6440Jetport Fire Squad159Firefighter (x2) 1991
64506450Mobile Police Truck771 Police Officer$18.751985
6480-16480Hook and Ladder Truck1181 Fireman$23.001985
6481 Construction Crew6481Construction Crew1682 1989
64826482Rescue Helicopter1983 1989
64836483Coastal Patrol243Police Officers (x3)$47.991994
6484-16484F1 Hauler269Mechanic (x2), Ben Steer 1995


Image#SetNumber of piecesMinifiguresPriceRelease
6750 Box6750Sonic Robot103Blue Classic Spaceman, Spaceman Reed 1986
6770 Futuron6770Lunar Transporter Patroller118Yellow Futuron Astronaut$26.751988
6780 Light & Sound XT - Starship6780XT Starship201Yellow Classic Spaceman 1986
6781 Box6781SP-Striker230Blacktron Astronaut, Space Police I Officer$28.001989
6783 Box6783Sonar Transmitting Cruiser345Red Classic Spaceman, Yellow Classic Spaceman, Robot OK$55.001986
6990 Box6990Monorail Transport System715Blue Futuron Astronaut (2), Yellow Futuron Astronaut (3)$155.001987
6991 Box6991Monorail Transport Base573Unitron Chief, Unitron Astronaut (x2), Major Kartofski$178.001994
6979 Box6979Interstellar Starfighter292Alpha Draconis, Chamon, Andy Droid$80.001997
6988 Box6988Alpha Centauri Outpost406Blacktron Future Generation Astronaut (x5)$80.001991


Image#SetNumber of piecesMinifiguresPriceRelease
4559 Box4559Cargo Railway8427$139.001996
45124512Cargo Train5443$140.002003
3225-13225Classic Train2813 1998
4551-14551Crocodile Locomotive3141 1991
45344534LEGO Express345$159.992002
45354535LEGO Express Deluxe762 2002
4565-14565Freight and Crane Railway9143 1996
4564-14564Freight Rail Runner5873$134.001994
High speed train4511High Speed Train3363 2003
K2159-1K2159Holiday Train Starter Collection9917$165.992006
Set45634563Load and Haul Railroad4763 1991
10001-110001Metroliner772Passenger (x7), Mayor Brickman, Train Driver, Railway Employee (x2)$149.002001
Set45584558Metroliner768Passenger (x7), Mayor Brickman, Train Driver, Railway Employee (x2)$149.001991
10132 boxart10132Motorized Hogwarts Express708Harry Potter, Ron Weasley, Professor Lupin, Dementor 2004
45604560Railway Express6589 1999
4561-14561Railway Express6659$139.001999
65537-Classic Freight Train65537Classic Freight Train613$80.002004
65801-165801Trains Value Pack7355 2005
K10173-1K10173Complete Holiday Train Collection9977 2006
7898 Box7898Cargo Train Deluxe8565$102.75 / €169.992006
7897 Box7897Passenger Train501Train Conductor, Passenger (2)$89.99 / €89.992006


Image#SetNumber of piecesMinifiguresPriceRelease
8094 Technic Control Center8094TECHNIC Control Center554 1990
8082 UBS8082Multi Model Control Set459€69.991993
8868-1-18868Air Tech Claw Rig954$139.991992
8457 Power Puller8457Power Puller9601$99.992000
8480 Space Shuttle8480Space Shuttle1366$157.991996
80648064Universal Motor Set219$54.991990
8421 Mobile Crane8421Mobile Crane1884$149.992005
8266-18266Spyder Slayer3632$69.991998
3038-13038Super Challenge3662 TECHNIC Figures$69.991998
8456-1-28456Fiber Optic Multi Set404$741996
8479-1-18479Barcode Multi-Set1280$163.991997
61BX5JZEBYL. SS500 8483CyberMaster9001 TECHNIC Figure 1998

Mindstorms, Educational, and Dacta[]

Image#SetNumber of piecesMinifiguresPriceRelease
96339633Advanced Air Power Set238 2002
9665-19665Mechanical Engineering318$149.991985
9609-19609Technology Resource Set1733 1995
97029702Control System Building Set2202 1993
9725 Set9725ROBOLAB Amusement Park Set3015$99.991998
9680-1-9563947469680Energy Work, Power Starter Set804$250.001999
9681-19681Renewable Energy Set710 1999
9684-0000-XX-12-19684Renewable Energy Set7294$169.992003
9685-19685Green Car Set47 2003
9665-19665Mechanical Engineering318$149.991985
9609-19609Technology Resource Set1733 1995
97029702Control System Building Set2202 1993
9725 Set9725ROBOLAB Amusement Park Set3015$99.991998
9719-19719Robotics Invention System727$200.001998
RI19747Robotics Invention System727$200.001999
38043804Robotics Invention System 2.0717$189.992001
9730-19730Robo Sports91$50.001998
Lego 97329732Extreme Creatures149$50.001998
97809780ROBOLAB Starter Set17024 1998
9735-19735Robotics Discovery Set387$150.001999
38013801Ultimate Accessory Set45 2000
97369736Exploration Mars156$49.992000
3800-13800Ultimate Builders Set321$60.002001


Image#SetNumber of piecesMinifiguresPriceRelease
1351-11351Movie Backdrop Studio209Grip , Policeman , Stunt Man$59.992001


Image#SetNumber of piecesMinifiguresPriceRelease
3582-Ant3582Ant258 1999
3591 Rota Beast3591Heli-Transport265 1998
3552 Hover-Sub with Motor3552Hover-Sub with Motor126 1998

Inventor & Creator[]

Image#SetNumber of piecesMinifiguresPriceRelease
4094-154094Motor Movers255$39.992003
48954895Motion Power611$49.992006