Wireless power?

One comment I got during our Christmas show this past weekend was I don't have enough lights on my layout :P

But seriously, I was asked if I was going to light up several of my cars.  The issue I have is having all the battery packs and even having the space to hide the pack.  One alternate I have done is run wire under the road to power a car up, but that is not elegant.

This lead me to the though of having induction power transfer units between the road and the car.  I see there are a few coils that are about the size of a 2x2 Round plate but I am not sure how much power they can transfer or is this even possible.

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  • Hi Jim Pirzyk ! Hmm, not enough lights.... 馃槈

    Have a look at this video:

    Is that what you were envisioning?  We have it working in the lab using the small receiver coils you mentioned.  Transmission distance is pretty decent (through a LEGO baseplate and then some), but due to the nature of the magnetic fields, transmission follows the circular outlines of the coils, which means multiple coils would be required for larger roads.

    Also, the coil requires 12V power, which is not our standard power source-- definitely doable, but it would require a somewhat different setup at shows.

    Another issue is that only LEDs can be powered-- no lighting effects or anything requiring a circuit or chip. (this is because the coils transmit at a very low amperage-- enough to drive one or even multiple LEDs, but not a chip)

    Lastly, wireless power by nature is very inefficient, so it requires a lot of power and current to drive small LEDs.  The setup above consumes 520mA at 12V to power six LEDs, so to have a club-type setup with multiple hotspots would require 12V power supplies capable of delivering 2, 3, or as much as 5A of power.  Again, not impossible, but definitely not your standard garden variety power supply.

    For many setups, though, we think it could be very cool.  Let us know what you think!

  • Yes the video is what I am thinking, though in the Mystery Machine video the coil is a bit large.

    Re 'hotspots' I was thinking if we can get coils small enough to fit w/i the 2x2 round tile, then you could hide the hotspots with a manhole cover w/i a brick built road.  Then have each one just power an individual car's lights.

    Re Amps: Most wall worts are have barely can push 1A of power (at 5V), the best one I found is only 2.4A distributed across 3 plugs and 1 A per plug max.

    This also would not work with the 3+1 wiring in future roads that I was envisioning.  One circuit for street lamps, one for these hotspots and one for the buildings, and all would be sharing the common neutral.

  • Jim Pirzyk With wireless power, the rule is the transmitting coil has to be very large.  There is no way you could have coils as small as you envision in the roads-- the small coils can only go inside/under the cars.

    For wall warts, try DigiKey or Mouser-- you can get 10A power supplies there!  And seriously, if this was something a club was looking at doing, they would probably want to go with a high-power model railroad transformer.  These are the kinds of amperages MRR clubs design around all the time.

    RE: your 3+1 wiring plan, my advice would be to not design it around 5V but to design it around the standard supply voltages used by DCC railroad layouts.  Why?  I could tell you, but then......you know.

  • Hi Jim Pirzyk and Rob Klingberg ,
    i would like to sell this in my brick store (offline).
    I have multiple customers that build a car system with train tracks under the baseplate and magnets. They always alsk me how to light up the cars and i am personaly interested, too. :D
    Most of the cars are very small so there is no space for a battery... i think this solution would solve it perfectly.

    Please help me where i can get a working sellable set for this... ?

  • Christian Volquardsen thanks for your interest.  Is this for slotcars or LEGO cars?  The wireless power is very attractive, but in practice it does not always work well.  The range is very short, and the cars need to be placed *exactly* on top of the transmitter.  if they move even 2mm, or rotate at all, the lights go off.  Also, the wireless power transmitters need to be right below the cars at all times-- it is not possible to for example have one large plate that transmits to all cars.  Each car needs a transmitter right below it.

    We will soon have a new lighting system for Speed Champions-type LEGO cars, putting batteries where people thought no battery could go.  This will work for any vehicle of any size (95% of them at least) and the battery will last multiple days, so this might be a better solution for you.

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